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Use of Acidic Electrolyzed Water Ice for Preserving the Quality of Shrimp
Abstract
Electrolyzed water ice is a relatively new concept developed in food industry in recent years. The effect of acidic electrolyzed water (AEW) ice on preserving the quality of shrimp (Litopenaeus vannamei) was investigated. Physical, chemical and microbiological changes of the shrimp were examined during the storage. The results showed that compared with tap water (TW) ice, AEW ice displayed a potential ability in limiting the pH changes of shrimp flesh, significantly (p<0.05) retarded the changes of color difference and the formation of total volatile basic nitrogen (TVBN). And AEW ice treatment had no adverse effects on the firmness of shrimp. Conventional plate count enumeration and PCR-DGGE demonstrated that AEW ice had a capability to inhibit growth of bacteria on raw shrimp, and the maximum reductions of population reached at >1.0 log CFU/g (>90%) at the 6th day. Moreover, AEW ice was clearly more efficient in maintaining the initial attachments between muscle fibers in shrimp according to histological section analysis. Based on above analysis, AEW ice can be a new alternative of traditional sanitizer to better preserve the quality of seafood in the future.
... However, bacteria usually cannot be inactivated and remain alive in food. Once aquatic products are exposed to appropriate conditions before consumption, the bacteria can multiply rapidly and cause food spoilage (Lin et al., 2013). Therefore, it is of profound significance to explore new methods to keep the quality of shrimp during storage. ...
... The bacteria in shrimp was counted by plating method (Lin et al., 2013). Briefly, 10 g of shrimps were mixed with 90 mL of saline solution (0.86 %), and then homogenized for 2 min in a filtered bag. ...
... The pH of shrimp was determined by the method of Lin et al. (2013) with some modifications. Briefly, 5 g of shrimp were added to 45 mL saline solution (0.86 %), and then homogenized for 3 min at room temperature. ...
A new protein complex (SAKP-Cur) was successfully prepared by combining soluble Antarctic krill protein with curcumin through hydrophobic action. The potency of photodynamic inactivation (PDI) mediated by the complex on preserving the storage quality of shrimp at 4 °C was investigated by microbiological, chemical, physical and histological methods. Results showed that the SAKP-Cur significantly improved the stability of curcumin, and greatly inactivated the native bacteria in shrimp driven by PDI. Meanwhile, the complex-mediated PDI effectively reduced the endogenous enzyme activity, the production of total volatile basic nitrogen (TVB-N) and malondialdehyde (MDA) in shrimp. Moreover, it obviously maintained the integrity and elasticity of the muscle fibers, thereby reducing the loss of water in myofibrils. Notably, the SAKP-Cur enhanced the PDI potency to preserve the freshness of shrimp during 4 °C storage or freeze–thaw cycles treatment. Therefore, the SAKP-Cur coupled with PDI is an effective fresh-keeping technology for aquatic products.
... Total volatile basic nitrogen (TVB-N): TVB-N was determined using the method of Lin et al. (2013). Briefly, the above homogenate (10.0 mL) was mixed with 1.0 g magnesia (MgO; Macklin Biotech Co., Ltd., Shanghai, China). ...
... As the storage period increased, the bacterial counts were quickly elevated enough to degrade the salmon proteins and produce alkaline compounds (e.g., ammonia compounds and trimethylamine), especially at the higher temperature (25 ℃) (Wang et al., 2017;Sun et al., 2019). The autolytic processes mediated by endogenous enzymes are also involved in the production of volatile bases (Lin et al., 2013). All these factors collectively contributed to the observed increase in pH. ...
... The unique fatty fibres and proteins of salmon meet the demand of consumers for the freshness and chewiness of fish. However, microbial growth and oxidation promotion accelerated the degradation of proteins and lipids in fish flesh, resulting in myofilament degradation and costamere distraction (Lin et al., 2013), which led to softening of muscle tissue and decrease in chewiness (Li et al., 2018;Offer and Knight, 1988). In this study, curcumin-mediated PDI potently inactivated the bacteria on the salmon, greatly decelerated protein degradation and effectively retarded lipid oxidation ( Fig. 3A-B, G-H). ...
The effect of curcumin-mediated blue light-emitting diode (LED) photodynamic inactivation (PDI) for preserving the quality of salmon contaminated with Listeria monocytogenes was investigated by microbiological, physical, chemical and histological methods during sample storage at 4 ℃ and 25 ℃. The results showed that PDI decelerated the proliferation of L. monocytogenes on salmon during storage at 25 ℃, with the maximum inhibition reaching 4.0 log10 CFU/g (99.99%), compared to the negative control. Moreover, PDI greatly retarded the increase in pH (P < 0.05) and the production of TVB-N, retarded the accumulation of free fatty acids, and decelerated the degradation of proteins, ultimately preserving the high nutritional value of the salmon. In addition, PDI effectively prevented a change in colour and retarded the loss of water from the salmon, thereby conserving its texture and sensory properties. Therefore, PDI is a promising and valid non-thermal technology to use for fish preservation.
... Total volatile basic nitrogen (TVB-N) was measured according to Lin et al. (2013). Oyster (10.0 ± 0.2 g) was homogenized with 40 mL 0.85% physiological saline solution for 5 min. ...
... The tissue sections of 7 μm were acquired by the RM2235 microtome (Leica Microsystems CMS GmbH, Wetzlar, Germany), and then hematoxylineosin stained routinely. All samples were observed and photographed by an optical RM2235 microscope (Lin et al., 2013). All experiments were conducted at least in triplicates. ...
... Lopez-Caballero et al. (2000) reported that the denaturation of myofibrillar fraction induced the increase of hardness, which led to aggregation and water loss during initial storage. However, as the temperature increasing, microbial growth and oxidation promotion accelerated the protein and lipid degradation rate of food, resulting in myofilament degradation and costameres distraction, thereby inducing the softening of muscle tissue and the decrease of hardness (Cheng et al., 2014;Lin et al., 2013). These facts greatly explained why the samples at 4 • C had a slightly changed hardness, but those at 10 • C and 25 • C presented an obviously decreased one. ...
Photodynamic inactivation (PDI) is a promising method with multiple targets to inactivate bacteria on food using visible light. Inactivation potency of the curcumin-mediated blue light-emitting diode (LED) PDI against the pathogen Vibrio parahaemolyticus on cooked oysters and its effects on the storage quality were investigated by the microbiological, physical, chemical and histological methods during storage at 4 °C, 10 °C and 25 °C. Results showed that the PDI treatment obviously inhibited the recovery of V. parahaemolyticus on oysters during storage, and the maximal difference attained >1.0 Log10 CFU/g (> 90%) compared to control stored at 10 °C and 25 °C. Meanwhile, it displayed a potent ability (p < 0.05) to restrain the decrease of pH values, reduce the production of total volatile basic nitrogen (TVB-N), suppress the lipids oxidation, as well as retard the changes of color difference of the oysters. In addition, the PDI effectively maintained the integrity and initial attachments of muscle fibers, and hence decreased the loss of water in myofibrillar space and the texture softening of oysters during storage. On this basis, this study facilitates the understanding of the potency of bacterial inactivation and food preservation of PDI, and hence pave the way for its application in food industry.
... The increased addition of PE to WG significantly increased the chewiness of salmon fillet during storage of 3-9 days compared to the control treatment and WG-coated salmon fillet (p ≤ 0.05). The decrease in the chewiness of fish muscle was attributed to the lipid oxidation, resulting in the myofilament degradation and costamere distraction [34]. The reduced springiness of the salmon fillet as the storage time increased from 0 to 9 days (p ≤ 0.05) was in line with [25]. ...
... In our findings, the increased addition of PE to WG improved the WHC of salmon fillet at day 9 significantly compared to other treatments (p ≤ 0.05), which was in accordance with Christensen et al. (2017) [37]. The decrease in the chewiness of fish muscle was attributed to the lipid oxidation, resulting in the myofilament degradation and costamere distraction [34]. The reduced springiness of the salmon fillet as the storage time increased from 0 to 9 days (p ≤ 0.05) was in line with [25]. ...
The effect of wheat gluten (WG)/phenolic extracts (PE) coating on the storage qualities of salmon fillets was studied. Porphyra haitanensis, belonging to red algae, possesses abundant phenolic compounds. Films were prepared by incorporating phenolic extracts (0, 0.5%, 0.75%, and 1.0%, w/v) from Porphyra haitanensis to WG. The PE showed strong antioxidant activities by scavenging DPPH and ABTS radicals. The increased addition of PE to WG film significantly increased tensile strength compared to that of WG film, but reduced water vapor permeability. The quality of salmon fillet stored at 4 °C from 0 to 9 days was decreased due to the oxidation of lipid and protein. However, the increased addition of PE to WG significantly reduced pH, TVB-N, TBA, peroxide value, total sulfhydryl content, and carbonyl content of salmon fillet compared to control salmon fillet. In addition, the increased addition of PE to WG also significantly improved water holding capacity, hardness, chewiness, and springiness of salmon fillet during storage compared to those of control salmon fillet. Taken together, this study showed phenolic extracts from Porphyra haitanensis improved wheat gluten-based film properties and further enhanced the qualities of coated salmon fillet during storage.
... [30] Another study suggest that NEW that contains lower ACC (60 ppm) can be applied on lettuce for disinfectant without interfering the quality of lettuce. [85] Yet in a study that investigate the antimicrobial efficacy of SAEW on mung bean showed that longer treatment time (15 min) can result lowered germination percentage after treatment. [36] However, future studies to focus on the investigation on the quality and nutrition value of various vegetables after application of EW. ...
... [31] Application of AEW ice on shrimp has demonstrated the potential ability in minimizing pH changes of shrimp flesh and significantly retarding the change of color, and it posed no adverse effect on the firmness of shrimp while had a capability to inhibit foodborne pathogen in shrimp. [85] However, there is insufficient studies investigate the effect of EW on seafood and fish quality hence more investigation should conducted. ...
... The raw shrimp results showed that AEW ice, besides its bactericidal effect on TVC, inhibited the pH changes, the formation of total volatile basic nitrogen (TVB-N), and the activity of Polyphenol oxidase (PPO) after 6 days of storage. These results in agreement with Lin et al. (2013) [228] indicate that AEW ice can serve as an innovative method to retain the quality of shrimps. In addition, lower TVB-N, trimethylamine (TMA), and thiobarbituric acid reactive substance (TBARS) values also reported for raw puffer fish (Takifugu obscurus) stored at 4 • C after treatment with weakly acidic EW (WAEW) and modified atmosphere packaging (MAP) [229]. ...
... The raw shrimp results showed that AEW ice, besides its bactericidal effect on TVC, inhibited the pH changes, the formation of total volatile basic nitrogen (TVB-N), and the activity of Polyphenol oxidase (PPO) after 6 days of storage. These results in agreement with Lin et al. (2013) [228] indicate that AEW ice can serve as an innovative method to retain the quality of shrimps. In addition, lower TVB-N, trimethylamine (TMA), and thiobarbituric acid reactive substance (TBARS) values also reported for raw puffer fish (Takifugu obscurus) stored at 4 • C after treatment with weakly acidic EW (WAEW) and modified atmosphere packaging (MAP) [229]. ...
A literature search and systematic review were conducted to present and discuss the most recent research studies for the past twenty years on the application of non-thermal methods for ensuring the microbiological safety and quality of fish and seafood. This review presents the principles and reveals the potential benefits of high hydrostatic pressure processing (HHP), ultrasounds (US), non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), and electrolyzed water (EW) as alternative methods to conventional heat treatments. Some of these methods have already been adopted by the seafood industry, while others show promising results in inactivating microbial contaminants or spoilage bacteria from solid or liquid seafood products without affecting the biochemical or sensory quality. The main applications and mechanisms of action for each emerging technology are being discussed. Each of these technologies has a specific mode of microbial inactivation and a specific range of use. Thus, their knowledge is important to design a practical application plan focusing on producing safer, qualitative seafood products with added value following today’s consumers’ needs.
... We performed a texture profile analysis (TPA) to determine the texture properties of the shrimp samples, using a texture analyzer (TAHDi/500, TAHD, UK) as outlined by Lin et al. [15]. A total of 40 abdominal sections per treatment group, as described in Section 2.2, were prepared for TPA and cutting force tests. ...
This study investigated the effects of pulsed electric field (PEF) treatment on the peeling efficiency and textural properties of whiteleg shrimp (Litopenaeus vannamei). Shrimp samples were treated at field strengths of 0, 1.0, 1.5, and 2.0 kV/cm to assess PEF impact on peeling force, incomplete peeling percentage, and texture profile. The results showed that PEF treatment significantly reduced the peeling force from 50.88 N in controls to 42.99 N at 2.0 kV/cm, while the percentage of incompletely peeled shrimp decreased from 27.5% to 15.9%. Texture profile analysis indicated that PEF treatment had no impact on the key properties of hardness and chewiness (no significant difference), with a reduction in springiness observed at higher field strengths. Improvements in peelability are attributed to electroporation, which disrupts collagen in the connective tissue between the shrimp shell and muscle. These findings indicate that PEF treatment is an efficient, non-thermal method for enhancing shrimp peeling processes while preserving textural integrity. PEF technology offers a promising alternative to traditional mechanical and thermal methods in the seafood processing industry.
... vannamei), highlighting its positive impact on seafood quality (Wang et al., 2014). To maintain shrimp quality, AEW ice exhibited bactericidal effects on TVC, reduced the formation of total volatile basic nitrogen (TVB-N), and decreased polyphenol oxidase (PPO) activity in raw shrimp during a 6-day storage period (Lin et al., 2013;Wang et al., 2014). Similarly, lower TVB-N, trimethylamine (TMA), and thiobarbituric acid reactive substance (TBARS) values were reported for raw puffer fish (Takifugu obscurus) stored at 4°C after treatment with weakly acidic electrolyzed water (WAEW) and MAP (Li et al., 2020). ...
The seafood industry faces significant challenges in preserving the quality and extending the shelf-life of its products to meet the demands of consumers for fresh, safe, and nutritious seafood. Apart from traditional pretreatments such as washing, sorting, and deheading, several emerging technologies like ozonized water (OW), acidic electrolyzed water (AEW), and plasma-activated water (PAW) have drawn attention for seafood industry. These innovative technologies not only improve quality of seafood but also effectively reduce contaminated microorganisms and enzymatic activity, thereby delaying spoilage. Furthermore, non-thermal processing technologies, including high pressure processing (HPP), cold plasma (CP) treatment, and modified atmosphere packaging (MAP), offer promising alternatives to conventional heat-based processes. These technologies are characterized by their ability to inactivate microorganisms and enzymes, while preserving the sensory attributes and nutritional value of seafood. HPP and MAP particularly have demonstrated their profound ability to extend the shelf-life of seafood products without compromising their quality or sensorial attributes. Furthermore, the synergistic effects of combining pretreatment and non-thermal processing techniques, have potential to prolong shelf-life and improve safety of seafood products. Thus, the integration of these pretreatments and technologies offers a promising avenue for enhancing the quality and safety of seafood products.
... Crustaceans contain a higher amount of non-protein nitrogen (NPN) compounds, such as trimethylamine oxide (TMAO), compared to fish. TMAO can undergo conversion into TVB-N molecules, which contribute to the development of unwanted off-flavors and odors, making TVB-N a common indicator for assessing the freshness, quality, and shelf life of seafood products [22]. In our study, cooked samples exhibited lower TVB-N values (13.5 ± 0.50 mg/100 g) compared to raw samples (15.12 ± 0.47 mg/100 g) (Fig. 1b). ...
Customers are increasingly opting for ready-to-eat and easy-to-prepare food products, such as cooked crayfish. It is highly valued for its unique taste, tender meat, and nutritional properties. Therefore, we conducted an investigation into its quality parameters over an 8-week period at − 20 • C. Parameters such as water distribution, oxidation reactions, color, microstructure, texture properties, and physicochemical parameters were examined. The physicochemical results indicated that as the storage time increased, the levels of pH and TVB-N (total volatile basic nitrogen) showed a significant increase, while the water holding capacity decreased significantly (P < 0.05). After two months of frozen storage, the carbonyl content and TBARS (thiobarbituric acid reactive substances) increased to 4.15 ± 0.16 nmol/mg protein and 1.6 ± 0.00 mg/kg, respectively. Additionally, the total sulfhydryl content decreased to 4.91 ± 0.10 mol/10 5 g protein, which had an impact on the quality of the crayfish. Electron microscopy revealed that with increasing storage time, the fiber structure gradually deteriorated due to water crystallization, leading to severe damage and breakage of muscle fibers. Interestingly, these changes related to storage affected color and texture parameters, thereby influencing the overall quality of the crayfish.
... However, the aquatic products are prone to deterioration, particularly shrimp with a high nutritional value [1,2]. In general, the quality of shrimp declines after death owing to the influence of autolytic enzymes and microbial contamination [3,4]. The frozen storage is the most commonly used method for preserving the quality of harvested shrimp, as it effectively slows down enzyme activity, inhibits microbial growth, and maintains the nutritional value [5]. ...
Thawing is the primary step in handling frozen aquatic products, which directly determines their end-product quality. This study firstly constructed a novel thawing method of ultrasound-assisted slightly basic electrolyzed water (UST), and its influences on the physicochemical and histological properties of shrimp, as well as the structural of myofibrillar proteins (MPs) in shrimp were evaluated. Results indicated that the UST treatment greatly reduced 48.9 % thawing time of frozen shrimp compared to traditional thawing approaches. Meanwhile, the UST effectively decreased the generation of malondialdehyde (MDA), total volatile basic nitrogen (TVB-N), and carbonyl compounds in the thawed shrimps. In addition, it significantly preserved the elasticity and integrity of muscle fiber. Notably, the UST reduced the damage of thawing to the spatial structures of MPs, thereby greatly keeping the stability of protein. All these favorable changes maintained the water holding capacity (WHC) and quality of shrimp. Therefore, the UST is a promising non-thermal thawing technology for aquatic products.
... In fact, the oyster has a richer carbohydrate content in the form of glycogen compared with the most aquatic products, and the glycogen is fermented into lactic acid to decrease the pH (He et al., 2006). However, the rich proteins in salmon are degraded to produce alkaline compounds, and besides, the autolytic process induced by the endogenous enzymes also results in the production of volatile bases, thus causing the increase of pH value (Lin et al., 2013;Sun et al., 2019). Taking the above facts into consideration, the PDI always restrains the pH change in comparison with the control groups. ...
The photodynamic inactivation (PDI) is a novel and effective nonthermal inactivation technology. This review provides a comprehensive overview on the bactericidal ability of endogenous photosensitizers (PSs)‐mediated and exogenous PSs‐mediated PDI against planktonic bacteria and their biofilms, as well as fungi. In general, the PDI exhibited a broad‐spectrum ability in inactivating planktonic bacteria and fungi, but its potency was usually weakened in vivo and for eradicating biofilms. On this basis, new strategies have been proposed to strengthen the PDI potency in food system, mainly including the physical and chemical modification of PSs, the combination of PDI with multiple adjuvants, adjusting the working conditions of PDI, improving the targeting ability of PSs, and the emerging aggregation‐induced emission luminogens (AIEgens). Meanwhile, the mechanisms of PDI on eradicating mono‐/mixed‐species biofilms and preserving foods were also summarized. Notably, the PDI‐mediated antimicrobial packaging film was proposed and introduced. This review gives a new insight to develop the potent PDI system to combat microbial contamination and hazard in food industry.
... Crustaceans contain more non-protein nitrogen (NPN) compounds than fish, such as trimethylamine oxide (TMAO), which can be transformed into TVB-N compounds, resulting in undesirable off-odors and off-flavors, so TVB-N is commonly used to determine the shelf life, quality, and freshness of marine products (Lin et al., 2013). The TVB-N of cooked crayfish treated with gamma-polyglutamic acid (2% and 4%) during a 2-month storage period at − 20 • C is shown in Fig. 1. ...
... Although AEW has rarely been reported to be applied to marine-capture shrimp, it is reported to significantly inhibit the proliferation of Vibrio parahaemolyticus, thereby maintaining the quality of fresh aquaculture shrimp and reducing the health threat of the pathogen during storage and transportation (Wang et al., 2014;Xie et al., 2012). AEW ice reportedly inhibits the growth of bacteria in aquaculture shrimp (Lin et al., 2013), destroys the conformation of PPO, slows down browning (Sun et al., 2018), and does not cause any adverse effects on shrimp (Wang et al., 2015). ...
Marine-capture shrimp is a general term for a type of shrimp that is different from marine-aquaculture shrimp. It is rich in protein, trace elements, and essential amino acids. It is an aquatic product with delicious meat and high nutritional and economic value. Most marine-capture shrimp are consumed fresh, with a small proportion subjected to processing. However, marine-capture shrimp is a highly perishable aquatic product, and hence, extensive preservation and processing methods have been developed to extend its shelf life. This review presents the current status of marine-capture shrimp in the world and the key issues (spoilage and melanization inhibition) regarding marine-capture shrimp preservation. Low-temperature preservation remains the predominant strategy for preserving marine-capture shrimp. Different preservation strategies combined with low temperature would maintain the quality of marine-capture shrimp more effectively, thereby extending the shelf life of the shrimp. The advantages and disadvantages of various preservation technologies are comprehensively considered and compared, as well as their scope of application. New processing technologies should be introduced, and various preservation technologies with complementary advantages should be organically combined to achieve the best preservation effect on marine-capture shrimp. This review provides a useful theoretical reference and a practical basis for future research on the shelf life extension of marine-capture shrimp.
... The C1, C3, and C10stored fillets seemed to retain their color more than the other fish fillets exhibiting the lowest color change values during the whole storage period; better results regarding the color stability were obtained for the PAI samples with the higher H 2 O 2 concentration (C10). The results are in agreement with the findings of Lin et al. (2013) who also noticed that the preservation of shrimp (Litopenaeus vannamei) in electrolyzed water ice retarded the changes of color difference and the formation of total volatile basic nitrogen (TVB-N) during refrigeration storage. ...
The efficacy and applicability of Plasma Activated Ice (PAI) -produced by cold atmospheric plasma (CAP) technology- on microorganisms and quality characteristics of perishable fresh sea bream (Sparus aurata) fillets, were evaluated. The changes in microbiological load and quality characteristics of fish fillets were investigated during storage with ice from deionized water (Control), PAI and ice from artificially produced water (Artificial) of H2O2 concentrations equal to those of PAI. Fresh sea bream fillets were packed under ice flakes (produced from PAI or Artificial or Control) on layers (as typically done in the relevant industry) and stored at 0.5 °C for 27 days. PAI application inhibited significantly the growth of microbial load of the fillets resulting in reduced growth rates while simultaneously significantly retarded the quality deterioration compared to the other disinfectant media. The use of PAI (with 10 mg/L H2O2) led to a 11-day and 6-day extension, i.e., 2-fold and a ∼ 1.5-fold extension, of the fillets shelf-life compared to the samples treated with Control and Artificial ice, respectively. The results proved the efficiency of PAI in extending the shelf-life of perishable foods during storage (or/and transportation), by validating its antimicrobial properties and cooling capacity.
... Postharvest chilling with ice (Bensid et al., 2014;Lin et al., 2013;Xuan et al., 2017), or freezing, successfully slows down enzymatic autolysis activity and the growth rate of many bacterial species (Adeyeye, 2017;Shawyer & Medina Pizzali, 2003). However, it does not kill the bacteria, and spoilage activates immediately upon thawing, limiting the shelf life. ...
With 40% of the South African population experiencing moderate to severe food insecurity and climate change predicted to impact agriculture negatively, there is a future role for inland fisheries to help feed 60 million people. To support the expansion of inland fisheries, reducing the current postharvest losses of ~25% of fish requires improving the current preservation and storage techniques. This review aims to assess the potential benefits for Sub-Saharan Africa’s freshwater aquaculture and fisheries to utilise an emerging technology to reduce postharvest losses, using South Africa as a case study. We demonstrate the potential for plasma activated water (PAW) for preserving fresh fish. PAW offers non-thermal and non-toxic bacterial inactivation. Considered safe for human use, PAW is currently used in medical applications and has been investigated as a postharvest sanitiser for many fruits and vegetables, effectively increasing the shelf life of fresh food. The limited studies of PAW treatment of fresh fish show increased shelf life with some generally insignificant changes to quality. This novel treatment's success depends on the optimisation of application methods, including PAW-derived ice (PAWDI). To strengthen the value chain of the fresh fish industry, PAW/PAWDI could extend the shelf life of fish from origin to market. Investment in food supply chain development would preserve more harvested fish and improve the quality. Utilising solar power to produce PAW or PAWDI in situ potentially offers benefits for the small communities of inland fisheries to commercial production. This technology as well as changes to traditional preservation and transport chains could be utilised in other Sub-Saharan African nations.
... Ovissipour et al. reported that the efficacy of using electrolyzed waters (e.g., natural and acidic) as antibiofilm agents, could be influenced by the rising temperature and effectively reduce the bacterial populations of L. monocytogenes in Atlantic salmon, without changing the fish proteins [77]. Moreover, acidic electrolyzed ice water could enhance the quality of shrimp by limiting the pH change in shrimp flesh and inhibiting the microbial growth on raw shrimp surfaces [78]. Another study revealed that smoked salmon fillets treated with nonthermal dielectric barrier discharge plasma for 60 min, reduced about 90% of L. monocytogenes [79]. ...
Biofilm is a complex matrix made up of extracellular polysaccharides, DNA, and proteins that protect bacteria against physical, chemical, and biological stresses and allow them to survive in harsh environments. Safe and healthy foods are mandatory for saving lives. However, foods can be contaminated by pathogenic microorganisms at any stage from farm to fork. The contaminated foods allow pathogenic microorganisms to form biofilms and convert the foods into stigmatized poison for consumers. Biofilm formation by pathogenic microorganisms in agri-farm industries is still poorly understood and intricate to control. In biofilms, pathogenic bacteria are dwelling in a complex manner and share their genetic and physicochemical properties making them resistant to common antimicrobial agents. Therefore, finding the appropriate antibiofilm approaches is necessary to inhibit and eradicate the mature biofilms from foods and food processing surfaces. Advanced studies have already established several emerging antibiofilm approaches including plant- and microbe-derived biological agents, and they proved their efficacy against a broad-spectrum of foodborne pathogens. This review investigates the pathogenic biofilm-associated problems in agri-farm industries, potential remedies, and finding the solution to overcome the current challenges of antibiofilm approaches.
... This value is referred to as ammonia, primary, secondary, and tertiary amines, and proteolysis products which have been used as a frequent and significant index to assess seafood quality (Yuan et al., 2016). A high value of TVB-N will cause an unpleasant and unacceptable odor (Lin et al., 2013). ...
This study examined the changes in the quality of the Pacific white shrimps coated with chitosan incorporated with custard apple peel extract (ASE). Generally, there was a positive effect on texture, color, and biochemical characteristics of shrimp samples treated with either chitosan coating or chitosan coating combined with ASE as against the control after 12 days of storage at 4°C. The increases in the values of weight loss, pH, peroxide values, total volatile basic nitrogen, and thiobarbituric acid reactive substances of shrimps were significantly inhibited in shrimps treated with a chitosan-ASE coating. Coating with chitosan combined with ASE at a concentration of 300 mg GAE/L was proven as the most effective preservation method for whiteleg shrimp during cold storage. Thereby, it may suggest that the combination of chitosan and ASE could be used as an effective alternative for the natural coating to extend the shelf-life and maintain the shrimp quality.
... For example, V. parahaemolyticus has been to form a biofilm on the chitin of diatoms and oysters and other marine organisms (Frischkorn et al. 2013;Aagesen et al. 2013). Even under high salt and temperature condition, Salmonella may contaminate shrimps, crabs, and other seafood (Lin et al. 2013;Bakr et al. 2011). Salmonella can also survive in the acidic environments, such as marinated shrimp and seafood salads (Wan Norhana et al. 2010). ...
The pathogenic microbial biofilm is gaining increasing concern in the food safety field. Biofilms may exist in food raw materials, food processing equipment as well as food products and packages during transportation and storage. Since the microbial biofilms have strong survivability in various pressure conditions (pH, temperature, ultraviolet, antibiotics, disinfectants, etc.) in food processing, they become a nonnegligible source of foodborne diseases, thus have potential threat to human health. Here, we focus on discussing the general phenomenon of food-associated pathogen biofilms, the survival mechanism of biofilms under various stimuli in food processing, commonly used detection methods, and the characteristic of virulence of biofilm.
... For the preservation of seafood, the AEW is normally frozen before use, and the term AEW ice is often used. AWE ice has been shown beneficial to improve the quality, shelf life, and food safety of several kinds of seafood, including shrimps (Lin et al., 2013;Wang et al., 2014;Zhang et al., 2015;Zhao et al., 2018) and squid (Xuan et al., 2017). Wang et al. (2014) suggested a primary mechanism improving the quality and safety of shrimps. ...
Recent years have shown a tremendous increase in consumer demands for healthy, natural, high‐quality convenience foods, especially within the fish and seafood sector. Traditional processing technologies such as drying or extensive heating can cause deterioration of nutrients and sensory quality uncompilable with these demands. This has led to development of many novel processing technologies, which include several mild technologies. The present review highlights the potential of mild thermal, and nonthermal physical, and chemical technologies, either used alone or in combination, to obtain safe seafood products with good shelf life and preference among consumers. Moreover, applications and limitations are discussed to provide a clear view of the potential for future development and applications. Some of the reviewed technologies, or combinations thereof, have shown great potential for non‐seafood products, yet data are missing for fish and seafood in general. The present paper visualizes these knowledge gaps and the potential for new technology developments in the seafood sector. Among identified gaps, the combination of mild heating (e.g., sous vide or microwave) with more novel technologies such as pulsed electric field, pulsed light, soluble gas stabilization, cold plasma, or Ohmic heat must be highlighted. However, before industrial applications are available, more research is needed.
... No negative effects were observed. [120] Farmed puffer fish (Takifugu obscurus) ...
Fish products are highly perishable, requiring proper processing to maintain their quality and safety during the entire storage. Different from traditional methods used to extend the shelf-life of these products (smoking, salting, marinating, icing, chilling, freezing, drying, boiling, steaming, etc.), in recent years, some alternative methods have been proposed as innovative processing technologies able to guarantee the extension of their shelf-life while minimally affecting their organoleptic properties. The present review aims to describe the primary mechanisms of some of these innovative methods applied to preserve quality and safety of fish products; namely, non-thermal atmospheric plasma (NTAP), pulsed electric fields (PEF), pulsed light (PL), ultrasounds (US) and electrolyzed water (EW) are analysed, focusing on the main results of the studies published over the last 10 years. The limits and the benefits of each method are addressed in order to provide a global overview about these promising emerging technologies and to facilitate their greater use at industrial level. In general, all the innovative methods analysed in this review have shown a good effectiveness to control microbial growth in fish products maintaining their organoleptic, nutritional and sensory characteristics. Most of the technologies have also shown the great advantage to have a lower energy consumption and shorter production times. In contrast, not all the methods are in the same development stage; thus, we suggest further investigations to develop one (or more) hurdle-like non-thermal method able to meet both food production requirements and the modern consumers’ demand.
... Meanwhile, SAEW-ice can extend the shelf life by 4-5 d compared with conventional ice water. AEW can inhibit the growth of bacteria in shrimp and significantly delay the color change and the increase of volatile basic nitrogen (p < 0.05) (Lin et al., 2013). This technology has broad-spectrum efficiency, safety, and environmental protection, the electrolyzed water generator structure is relatively simple, and the production cost is relatively low (Ma, et al., 2019). ...
This article reviews the research progress of non-thermal disinfection technologies in food and introduces the principles of non-thermal disinfection technologies such as ultra-high pressure, ozone, acid electrolyzed water, irradiation, magnetic sterilization, high-pressure carbon dioxide, and natural antibacterial. We discuss the characteristics and application progress of non-thermal disinfection technologies in food processing and analyze their development trend based on their application and promotion in food processing and storage.
... EW ice is a novel concept developed recently to preserve the quality of aquatic products. Lin et al. (2013) demonstrated that AEW ice (pH = 2.46, ORP = 1124 mV, and ACC = 26 mg/L) inhibited the growth of aerobic bacteria on shrimp (Litopenaeus vannamei), and the maximum reductions of population achieved greater than 90% on day 6. Additionally, AEW ice significantly delayed the color change and the production of total volatile basic nitrogen (TVBN), as well as retaining the initial adherences between muscle fibers of shrimp. ...
With the growing demand for safe and nutritious foods, some novel food nonthermal sterilization technologies were developed in recent years. Electrolyzed oxidizing water (EOW) has the characteristics of strong antimicrobial ability, wide sterilization range, and posing no threat to the humans and environment. Furthermore, EOW can be used as a green disinfectant to replace conventional production water used in the food industry since it can be converted to the ordinary water after sterilization. This review summarizes recent developments of the EOW technology in food industry. It also reviews the preparation principles, physical and chemical characteristics, antimicrobial mechanisms of EOW, and inactivation of toxins using EOW. In addition, this study highlights the applications of EOW in food preservation and safety control, as well as the future prospects of this novel technology. EOW is a promising nonthermal sterilization technology that has great potential for applications in the food industry.
... In addition, AEW served as a potential substance for decreasing the activity of cathepsin B and polyphenol oxidase. Lin et al. [10] also proved that AEW ice can mitigate changes in pH, color, and the formation of total volatile basic nitrogen of shrimp. Chung et al. [11] investigated how HClO and ClO 2 affect the disinfection of fresh vegetables and fruits, and the authors suggested that ClO 2 efficiently decreased the total bacterial counts, compared to the HClO treatment. ...
Mussel (Mytilus edulis) is an economic shellfish with a high nutritional value. Due to the high amount of protein and fat, fresh mussels are susceptible to spoilage during storage. In the present study, how a combination of pullulan, acidic electrolyzed water (AEW), and stable chlorine dioxide (ClO2) ice-glazing treatments affect the quality of mussels was investigated during 90 days of frozen storage. The results indicate that the combined glazing treatment effectively maintained the mussel muscle quality during storage mainly due to its air barrier actions. Mussel samples coated with AEW and ClO2 showed lower aerobic plate counts than other groups, resulting from the strong antibacterial action of AEW and ClO2. After 90 days of frozen storage, the mussel glazed with a combination of AEW, ClO2, and pullulan solutions showed better texture properties, higher content of myofibrillar proteins, higher Ca²⁺-ATPase activity, and more SH groups than the other glazing treatments. The water-holding capacity and SEM observations showed that the pullulan glazing efficiently inhibited the physical damage caused by the frozen and long-term storage, which mainly contributed to the high amount of hydrophilic hydroxyl groups in the muscle tissues. The present study supports the use of a combination of cryoprotectants for extending the shelf-life of frozen mussel products during long-term storage.
... Electrolyzed water (EW) is widely accepted as a practical disinfectant because it does not make use of hazardous chemical substances and processes [2]. Studies have shown that EW has gained immense popularity because of its ease of production and application; therefore, it has been extensively applied in food sanitization [1][2][3][4][5][6][7][8][9][10], environmental sanitization [11], livestock farming [12][13][14][15][16][17][18], and medical sterilization [19][20][21][22][23]. ...
Currently, electrolyzed water, a sustainable and environmentally friendly disinfectant produced through electrolysis of an acid or salt, has become very popular because of its applications in various sectors such as health, agriculture, and food. Influencing factors are important for optimizing the electrolyzed water production process and maximizing application efficiency. Factors that influence the production and efficiency of electrolyzed water, including water and electrolyte properties, electrode material, current, storage, and application factors, were reviewed in this study. Moreover, some commercially available generator models, their specifications, and issues are discussed along with future recommendations. This work summarizes the available literature from January 2000 to December 2020, reporting studies that can assist in understanding various parameters affecting the production and stability of electrolyzed water. This can provide further insights and aid researchers in optimizing the process and address the issues faced by the existing systems by offering new perspectives in future studies.
... SAEW exhibits strong antimicrobial activity against many different kinds of microorganisms such as Escherichia coli [19], Staphylococcus aureus [19,20], Salmonella spp [21], Vibrio parahaemolyticus [22], and Bacillus cereus spores, etc. [23,24]. SAEW has been used to disinfect fresh fruits [25], vegetables [26,27], fish products [28,29], and meat products [30]. In addition, SAEW shows potential on controlling some phytopathogenic fungi. ...
Effects of ultrasound (US, 300, 400, and 500 W) and slightly acidic electrolyzed water (SAEW, 10, 30, and 50 mg/L) combination on inactivating Rhizopus stolonifer in sweet potato tuberous roots (TRs) were investigated. US at 300, 400, and 500 W simultaneous SAEW with available chlorine concentration of 50 mg/L at 40 and 55 °C for 10 min significantly inhibited colony diameters (from 90.00 to 6.00-71.62 mm) and spores germination (p < 0.05). US+SAEW treatment could destroy cell membrane integrity and lead to the leakage of nucleic acids and proteins (p < 0.05). Scanning and transmission electron microscopy results showed that US+SAEW treatment could damage ultrastructure of R. stolonifer, resulted in severe cell-wall pitting, completely disrupted into debris, apparent separation of plasma wall, massive vacuoles space, and indistinct intracellular organelles. US500+SAEW50 treatment at 40 and 55 °C increased cell membrane permeability, and decreased mitochondrial membrane potential of R. stolonifer. In addition, US500+SAEW50 at 40 °C and US300+SAEW50 at 55 °C controlled R. stolonifer growth in sweet potato TRs during 20 days of storage, suggesting effective inhibition on the infection of R. stolonifer. Therefore, US+SAEW treatment could be a new efficient alternative method for storing and preserving sweet potato TRs.
... It is suggested that the AEW treatment on smoked-salmon did not alter texture, color and sensory perception of the food product [31]. Application of AEW ice on shrimp has demonstrated the potential ability in minimizing pH changes of shrimp flesh and significantly retarding the change of color, and it posed no adverse effect on the firmness of shrimp while had a capability to inhibit foodborne pathogen in shrimp [99]. However, there is insufficient studies investigate the effect of EW on seafood and fish quality hence more investigation should conducted. ...
Uncontrolled growth of microorganism in foodstuff pose a severe challenge to the food industry, as it could leads to food spoilage, or even foodborne disease if the microorganism is pathogenic. To deal with these threats, sanitizers has been widely applied widely by food industry. In the last two decades, electrolyzed water (EW) has been food to be a promising new sanitizer for food industry, as it is more environmentally friendly compared to conventional chlorine-based disinfectants. This paper reviews the recent progress on the application of EW as a food sanitizer. EW was produced by the electrolysis of diluted NaCl (or HCl) solution and could be classified into several subgroups (acid EW, slightly EW, neutral EW, alkaline EW, low concentration) based on their pH and available chlorine concentration. The efficacy of using EW to inhibit the growth of several most important microorganism of food safety concern were proven by numerous studies. Besides, the application of EW has been seldomly associated with detrimental effects on the nutritional and sensory proprieties of food. However, its antimicrobial potency was affected by factors such as pH, temperature, storage time, and organic matter.
... Although an increased understanding has been achieved in recent years concerning the softening in postmortem shrimp muscle (Qian, Xie, Yang, & Wu, 2013;Navarrete-del-Toro, García-Carreño, Hernández-Cortés, Molnár, & Gráf, 2015;Okpala, 2015;Annamalai et al., 2015;Nunak & Schleining, 2011;Lin et al., 2013), few studies have focused on the behavior of proteolytic enzymes during storage. Investigations on the softening of muscle demonstrated a protease mediated activity on muscle tissue during storage Chen, Guttmann, Xiong, Webster, & Romaire, 2008;Garcia-Carreno, Hernandez-Cortes, & Haard, 1994;Brauer et al., 2003;Ezquerra, García-carreño, & Haard, 1997;Sriket et al., 2012b;Lu, Liu, & Tsai, 1990;Sriket, Benjakul, Visessanguan, & Kishimura, 2011). ...
Fluorescein-isothiocyanate (FITC) labeled trypsin-like protease was prepared and injected into the hepatopancreas of white shrimp. Different segments of the injected shrimp were analyzed with a fluorescence microscope during storage. FITC-trypsin-like protease can be detected in the first segment of shrimp muscle at day 4, while it cannot be observed in the second segment until day 6. The results showed that trypsin-like protease can migrate from hepatopancreas to the tail portion. Texture profile analysis showed that soybean trypsin inhibitor retarded the softening of the shrimp muscle. The rheological results revealed that the content of myosin heavy chain (MHC) in shrimp muscle was decreased with the extended storage time. Proteomics analysis displayed that trypsin-like protease accelerated the metabolism of postmortem muscle. It can be concluded that trypsin-like protease migrated from the hepatopancreas to the muscle tissue, degraded myofibrillar protein, deteriorated the muscle texture, and eventually leaded to the softening of white shrimp.
Fresh seafood and agricultural products are susceptible to microbial contamination, leading to resource waste and
safety risks. Electrolyzed water (EW), an environmentally friendly agent, can inactivate microorganisms and prolong the shelf life of
food. Considerable attention has been devoted to its potential in guaranteeing food quality and safety. This review focused on the
effectiveness of both acidic electrolyzed water (AEW) and alkaline electrolyzed water (AIEW) in inactivating bacteria and fungi and
degrading mycotoxins. Additionally, newly developed acidic electrolyzed water ice (AEW ice) and its preservation effect were
evaluated. Notably, the AEW ice could greatly inhibit the growth of exogenous microorganisms and the activity of endogenous
enzymes, thereby preventing the deterioration of seafood. Additionally, the novel applications of AIEW combined with several
emerging technologies, including ultrasound and photodynamic inactivation (PDI) were also summarized. However, there are
several challenges regarding the future development of EW in the food industry, including constructing efficient technologies to
enhance the stability and durability of AEW, developing equipment for continuous production of AEW ice, improving the
inactivation efficiency of EW against microorganisms in food matrices, identifying action targets, and elucidating eradication
mechanisms of EW against bacterial biofilms, etc. This Perspective will provide new findings into the knowledge, deficiency, and
potential applications of EW in the food industry.
Antarctic krill proteins (AKP) were successfully glycosylated by inulin driven by ultrasound (300 W, 20 min) and pH shift (11.0) to prepare the conjugates of glycosylated AKP and curcumin. The preservation effects of the conjugates-
mediated photodynamic inactivation (PDI) on the storage quality of salmon fillets were investigated. Results showed that the glycosylated AKP (AKP-pH11-U20) exhibited a significantly increased solubility, and a relatively small and loose morphology characterized by SEM, an unfolded and disorganized structure by FTIR and intrinsic fluorescence analysis, and a decreased surface hydrophobicity by bromophenol blue staining, and all these changes contributed to its reduced surface tension. On this basis, the glycosylated AKP efficiently loaded curcumin (323.4 μg/mg) to form the conjugates, and the conjugates-mediated PDI greatly inhibited 99.8% bacterial cells and the migration of water, retarded the change of color and pH, suppressed the lipid oxidation and degradation during 4 °C storage for 7 days, compared to the conventional curcumin-mediated PDI. This study expands the application of new marine protein resources in preserving the quality of aquatic products.
Maintaining precise temperature control is vital for cold chain food transport, as temperature fluctuations can cause significant food safety and quality issues. During transport, ice that melts can promote the growth of microbes and their spread, resulting in microbial cross‐contamination. This study developed sustainable, non‐melting, self‐sanitizing “ice cubes” using food grade compositions including microporous cellulose sponges (MCS) and photosensitizers, aimed at enhancing temperature regulation and minimizing microbial contamination in the cold chain. Upon absorbing water, the MCS matched traditional ice in cooling efficiency and heat absorption and exhibit remarkable mechanical and thermal durability, withstanding multiple freeze‐thaw cycles and compressive stresses. The cationic MCS combined with erythrosine B demonstrated strong self‐sanitizing capabilities, effectively reducing microbial cross‐contamination in food models. Additionally, the release rates of photosensitizers from the MCS can be modulated by altering environmental ionic strength. This research offers viable solutions to address microbial cross‐contamination challenges in current cold chain systems.
The combined effects of acidic electrolyzed water (AEW) depuration and high pressure processing (HP–P) on reduction of growth of spoilage bacteria and pathogens in blood clams (Tegillarca granosa) during cold storage were investigated. After HP-P treatment of depurated blood clams at 300 MPa for 3 min (HD-300), total viable count (TVC), psychrophilic bacteria count (PBC), presumptive Gram-negative, Vibrio parahaemolyticus, lactic acid bacteria, and Pseudomonas spp. in blood clams were completely inactivated at day 0. TVC of HD-300 was lower than the limit (6 log10 CFU/g) up to day 9, while untreated sample could be kept less than 3 days. HD-300 clam sample also showed the higher expansion rate and shucking ratio. In addition, lower reductions in heme iron content, a* value (redness), moisture content and texture properties were observed in HD-300. This coincided with lower total volatile basic nitrogen content, fatty acid oxidation than other samples (p < 0.05). Based on histological study, intestine, mid gut gland, gonad, and gill were moderately disrupted in HD-300. Overall, AEW depurated blood clam in combination with HP-P (300 MPa, 3 min) effectively reduced TVB-N formation, maintained the heme iron content, and prolonged the shelf-life of blood clam for 9 days at 4 ◦C.
Slightly Alkaline electrolyzed water (SAlEW) is used as cleaning agent for removal of greasy materials and
organic matters from surfaces and also appears to have antimicrobial effect. While, slightly acidic electrolyzed
water (SAcEW) act as sanitizing agent for food and food contact surfaces. In the current work, Aerobic plate count
(APC) of examined fresh fish samples (mean log10cfu/g) was within the permissible limit (5.7±0.01, 5.94±0.015,
5.99±0.04 and 5.9±0.01) till the 5
th
, 7
th
, 9
th and 11th days of preservation in ordinary non-treated water ice,
SAlEW, SAcEW and SAlEW followed by SAcEW-ice, respectively. The judgment depends on the permissible
limits mentioned by ES (No.3494/2019). By matching Psychotrophic count using APC as a guide, the samples
recorded 3.94±0.015, 4.96±0.02, 4.87±0.02 and 4.93±0.01 till the aforementioned days as well as types of water
used in the experiment. Meanwhile, Coliform count recorded 2±0.07, 1.99±0.09, 1.95±0.02 & 2±0.02 for the same
former days and also by using the same water treatments. In addition, Staph. aureus count recorded 2.94±0.01,
2.99±0.07, 2.91±0.02 & 2.93±0.02 at the 6th, 7th, 10th and 12th days respectively by using the same aforementioned
water types. In conclusion, using of SAlEW followed by SAcEW had a highly decontamination effect as well as
prolong the shelf-life of examined fish followed by SAcEW, SAlEW and finally ice made from ordinary water.
Chemical analysis (TVB- N & TBA) should not be relied to determine the freshness of the fish, as they were
within the permissible limits, despite the bacteriological spoilage of the samples.Overall Sensory parameter scores
showed balanced results in their acceptability scores which were parallel to the bacteriological analysis.
This study observed that when plasma-activated water (PAW) was combined with organic acid, it showed a synergistic inactivation effect on Listeria monocytogenes, which is highly resistant to PAW. When comparing various organic acids, lactic acid (LA) showed the greatest synergistic effect, followed by malic acid (MA), citric acid (CA), and acetic acid (AA), whereas propionic acid (PA) did not show a synergistic effect. Organic acid lowered the activity of ROS defense enzymes (catalase, superoxide dismutase) by reducing intracellular pH (pHi), which induced the increase in the accumulation of ROS of PAW within the cell. In the end, the synergistic inactivation effect appeared as the increased occurrence of oxidative damage when organic acid was combined as a series of preceding causes. In this case, LA with the greatest ability to lower the pH induced the greatest synergistic effect, suggesting that LA is the best candidate to be combined with PAW. As a result of observing changes in inactivation activity for L. monocytogenes of PAW combined with 1.0% LA while storing at - 80, -20, 4, 25, & 37 °C for 30 days, respectively, it was confirmed that the lower the temperature, the lower the activity loss during the storage period, and that it had an activity of 3.72 log reduction based on 10 min treatment when stored at - 80 °C for 30 days. Application of PAW combined with 1.0% LA stored at - 80 °C for 30 days to mackerel inoculated with L. monocytogenes in ice form resulted in a decrease of 4.53 log after 120 min treatment, without changing the quality of mackerel. These results suggest that combining LA with PAW can be an effective control strategy for L. monocytogenes with high resistance to PAW, and can be effectively utilized, even in ice form.
In this study, electrolyzed water (EW), which is being used for disinfection in various
food production applications, is discussed. Today, research on green production has intensified, aiming to preserve food for a longer time, using fewer chemicals or none, in order to preserve the initial nutritional properties of the food and deliver it to the consumer. In this context, it is an undeniable fact that there is a need to improve existing methods and practices and develop new technologies for the long-term storage of foods without quality losses and health concerns. One of the
methods developed for this purpose is the use of electrolyzed water in food disinfection. While the use of electrolyzed water in various stages of the food processing industry creates a relatively new field of application, many studies have focused on its antimicrobial and antioxidant activity. However, studies on the use of this method in the fish processing industry are very limited and need to be developed. Previous studies are mainly related to the antimicrobial properties of electrolyzed water and there are limited studies on the effects of seafood products on storage times (shelf life). However, in light of the studies, it is seen that electrolyzed water has potential uses for the seafood processing industry.
Bu çalışmada çeşitli gıda üretim alanlarında dezenfeksiyon amaçlı kullanımı yaygınlaşmakta olan elektrolize sular ele alınmıştır. Günümüzde gıdaların ilk andaki besin özelliklerinin korunarak tüketiciye ulaştırılması için daha az ya da hiç kimyasal kullanılmadan daha uzun süreli olarak saklanmasını amaçlayan yeşil üretime yönelik araştırmalar yoğunlaşmıştır. Bu kapsamda gıdaların kalite kayıpları olmaksızın ve sağlık endişeleri yaratmadan uzun süreli saklanmasına yönelik var olan yöntem ve uygulamaların iyileştirilmesi ve yeni teknolojilerin geliştirilmesine gereksinim olduğu da yadsınamaz bir gerçektir. Bu amaçla geliştirilen yöntemlerden birisi de gıda dezenfeksiyonunda elektrolize suların kullanımıdır. Gıda işleme endüstrisinin çeşitli aşamalarında elektrolize suların kullanımı görece yeni bir uygulama alanı oluştururken, son zamanlarda yapılan çalışmalarda özellikle antimikrobiyal ve antioksidan ajan olarak da üzerinde durulmaktadır. Buna karşın bu yöntemin su ürünlerinde kullanımına yönelik çalışmalar oldukça sınırlı olup, geliştirilmesine gereksinim bulunmaktadır. Önceki çalışmalar ağırlıklı olarak elektrolize suların antimikrobiyal özellikleri ile ilgilidir ve su ürünlerinin saklama sürelerine (raf ömrü) etkisi ile ilgili olarak sınırlı sayıda çalışma bulunmaktadır. Bununla birlikte yapılan çalışmalar ışığında elektrolize suyun su ürünleri işleme endüstrisinde potansiyel kullanımları olduğu görülmektedir.
Background
Shrimp is widely distributed and world-favored fishery products with increasing growth of market requirement. Nowadays, more and more consumers pay increasing attentions on the freshness and safety of aquatic products. However, shrimps are highly perishable and textural deterioration due to the combined actions of enzymatic proteolysis and microbial metabolism during post-harvest preservation and retailing procedures. Thus, developing practical and effective preservation technology to dramatically maintain quality of shrimp has attracted lots of attentions. This review provides a comprehensive overview of various preservation technologies (eg. modified atmosphere packaging, high pressure, food irradiation, cold plasma et al.) that have been investigated to guarantee the quality of shrimp underlying preservation mechanisms.
Scope and approach
The goal of this review is to critically update and discuss the spoilage mechanism and quality changes of shrimp during storage, and the recent advances preservation technologies on the quality of shrimp are also discussed. Besides, the advantages or disadvantages of each technology and limited applications of novel preservation technologies are also discussed.
Key findings and conclusions
Shrimp spoilage immediately happen after death, the enzymatic proteolysis, microbiota composition and metabolism are the main factors that decrease freshness, texture and quality of shrimps. Traditional preservation technology has been widely used, but it still can't efficiently guarantee shrimp quality. Various novel preservation technologies have been successfully proposed to effectively prolong the shelf-life of shrimp with high quality, showing high market values throughout the supply chain of shrimps. However, extensive studies are still required to be performed to make them commercialized.
Novel environment‐friendly heat‐storage materials with efficient cooling capacity are in high demand by the food, pharmaceutical, and related industries and supply chains. Better control and prevention of cross‐contamination caused by meltwater from traditional ice have become critical to ensure the safety and quality of food and other commodities. Here is reported a microbial‐resistant, reusable, and compostable novel stationary cooling medium, “Jelly Ice Cubes” (JICs), based on gelatin–menadione sodium bisulfite (MSB) hydrogels (Gel/MSB‐JICs) with cooling efficiency comparable with traditional ice. For the first time, the photo‐crosslinking reactions induced by MSB are proposed and validated theoretically and experimentally. Photo‐tuning is used collectively with rapid‐freeze‐slow‐thaw treatment to construct robust hydrogel frameworks against the functional and structural damages caused by the phase transition of water during repeated uses. Exceptionally stable cooling efficiency and robust mechanical strength are observed across ten application cycles, with stable antimicrobial functions against bacteria, fungi, and yeast. At the end of the lifecycle of JICs, they can be composted or used as a soil treatment to promote plant growth. The novel JICs are competent as promising, safer, and more eco‐friendly substitutes for traditional ice and ice packs.
Food safety is a burning issue in the present world. Safe sanitizers are obligatory for maintaining quality of food and increasing the shelf life of fresh produce and other agricultural products. Food industries have been using electrolyzed water (EW) as a unique sanitizer for the past two decades which has excellent results to reduce the microbial count. Hurdle technology, e.g., combination of EW with ultrasonication, short-term heat treatment, organic acids, and salts, found to have more effective results in reducing microorganisms which overcame the little shortcomings with EW like corrosiveness and maintained organoleptic qualities. In this chapter, we are going to discuss the production of EW and its combination with ultrasonication, short-term heat treatment, organic acids, and salts to produce a novel sanitizer.
Ice refrigeration is one of the most widely used methods for food preservation with the use of a low temperature to delay the growth of any microbial contaminants. The production of safe edible ice with antimicrobial properties is of importance to food safety and human health, and has attracted increasing interest in recent years. This manuscript summarizes the advancements of the recent technologies to produce activated ice containing bactericidal agents, which can be potentially applied for the microbial decontamination and freshness retention of raw foods, such as fresh vegetables, seafood and fisheries. Cold atmospheric plasma and acidic electrolysis of water are two technologies that have been recently proposed for the treatment of water that is intended for the production of safe ice. Additionally, the application of ultraviolet light-emitting diode (UVC-LED) irradiation for the efficient disinfection of the edible ice is also discussed.
The present work mainly investigated the effects of prepared chitosan‑sodium alginate-nisin (CS-SA-N) preservatives on the quality and bacterial phase of Penaeus vannamei shrimp during cold storage. Results showed that CS-SA-N preservatives treated samples had the lower pH, total volatile basic nitrogen (TVB-N), total viable count (TVC), and freeness (K) values than those of untreated ones during cold storage. The sensory evaluation results indicated that CS-SA-N preservatives treated shrimps had the higher comprehensive scores than those of untreated ones during whole storage. Microbial community of all samples was dominated by Proteobacteria. The initial predominant bacteria of fresh shrimps were Sphingomonas, Carnobacterium and Psychrobacter. Psychrobacter, Pseudomonas, and Shewanella, Acinetobacter and Vibrio were the predominant bacteria of untreated samples. CS-SA-N preservatives significantly decreased predominant microbial numbers by inhibiting the growth of Psychrobacter, Vibrio, Acinetobacter and Carnobacterium during cold storage. Therefore, the CS-SA-N preservatives could be used to prolong the shelf life of shrimp and guarantee its quality.
Crustaceans are animals that do not have a vertebra and backbone and have a hard shell outside. The body of crustaceans is divided into three parts. These are head, thorax, and abdomen. Body consists of segments and jointed legs. Commercially used crustaceans can all be grouped together and called as decapods because they have 10 ft. The first leg pair is usually larger than the rest. These are called claws. Decapod crustaceans are distinguished from other crustaceans by having five pairs of pereiopods or ten walking legs. Shrimps, prawns, lobsters, and crabs are decapod crustaceans. Crustacean shellfish have economic importance and important places in trade of the world. These creatures are very sensitive to degradation and therefore care must be taken to maintain them immediately after catching or harvesting. Otherwise there may be significant quality and economic losses. For all these reasons, preservation and handling is an important issue for crustacean shellfish.
The combined effect of slightly acidic electrolyzed water (SAEW) and ascorbic acid (AA) on the melanosis and quality of freshwater prawn (Macrobrachium rosenbergii) over a period of 6 days cold storage was investigated. AA solution (3 g/L) was used to immerse the prawn after prewashing with SAEW (pH 5.92; ORP, 810 mV; ACC, 20 mg/L). Prawn physicochemical (pH, texture and total volatile basic nitrogen), microbiological (total aerobic counts and psychrophilic bacterial counts) and sensory characteristics were all analyzed. SAEW + AA treatment could effectively retard melanosis, bacterial growth and protein degradation and maintain better texture and sensory characteristics compared with AA solution, AEW and SAEW treatment alone. The process efficiency of this combination was higher than that of individual treatment. SAEW + AA treatment prolonged the shelf life of freshwater prawn by 3 days during storage at 4 °C. The results indicate that immersion in AA combined with SAEW prewashing has potential as a promising method to maintain the quality and extend the shelf life of prawns during refrigerated storage.
Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidation-reduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of −800 to −900 mV. Vegetative cells of various bacteria in suspension were generally reduced by >6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.
Trimethylamine (TMA) and the total volatile basic nitrogen (TVBN) were determined in 169 samples of sea-fish (herring, cod, whiting, and mackerel) at all stages of decomposition. The comparison of these two parameters with the ratio P=TVBN/TMA (%) showed that P provides a useful index of freshness. It is relatively constant between species, its dispersion is less than that of TMA and it increases more rapidly than TVBN at the start of decomposition. Statistical analysis of the experimental results showed that there is a non-linear correlation between P and the decomposition index (i). The comparison of the line-equations defining log P as a function of i for different species of marine Teleostei led us to show that there is little or no intraspace variation of this correlation under determined conservation conditions. It is noted that for a given species, this correlation is temperature-dependant. Statistical exploitation of these results permit us to determine the maximal admissible values for P which ca...
The obscure puffer fish (Takifugu obscurus) is underutilized as a food fish. To improve the quality of puffer fish flesh, the fish samples were preserved after treating them with electrolysed water (EW), a combination of EW and chitosan (EW/chitosan), or a combination of EW and carboxymethyl chitosan (EW/CMC). The effects of these treatments were compared by analysing changes in the total viable count of aerobic bacteria, firmness, total volatile basic nitrogen, trimethylamine, pH, the thiobarbituric acid and sensory attributes of the refrigerated puffer fish. Changes in the myofibril length of puffer fish flesh was also studied, which is related to flesh softening. The findings suggest that during storage, EW/chitosan treatment is more effective than both EW and EW/CMC treatments in inhibiting microbial growth and myofibril degradation, and in maintaining the quality of obscure puffer fish flesh. This could extend the shelf life by 50% of the original shelf-life of about 4 days of the fish samples.Highlights► We use three different treatments to preserve obscure puffer fish flesh. ► We study changes in the myofibril length of puffer fish flesh during storage. ► EW/chitosan treatment extends the shelf life by 50% of the original shelf-life. ► The decrease in myofibril length is related to the firmness changes of fish flesh.
The sensory, microbiological and biochemical changes were determined in shrimp (Penaeus merguiensis) stored at 0° to 35°C. Mean aerobic plate count of fresh shrimp, initially 5.0 × 105 CFU/g, increased with time and temperature to 6.4 × 109 CFU/g at 35°C after 24 hr. A total of 560 different bacteria were isolated and identified. In addition, the dominant organisms were tested for ability to reduce TMAO, produce indole and hydrolyze protein. The initial bacteria were 30% Gram + organisms but changed to predominantly Grampsychrotrophs at lower temperatures and to mesophiles at higher temperatures. Odor, texture and color qualities decreased; TMA, TVB, pH and Indole increased with time and temperature. Shelf life of shrimp ranged from 7 hr at 35°C to 13 days at 0°C.
The objective of this study was to determine the changes in the quality of coated trout fillets after coating with edible materials. Fillets were coated and stored at −18 °C for a period lasting up to 7 months. Coating materials were applied in three different stages (first, second, and last coatings). The coated fillets were fried and analyzed for oil absorption and moisture content throughout the storage period. Sensorial attributes and the physical–biochemical changes were also measured before the frying process in each month. It was observed that it is more advantageous to use gluten as the first coating, xanthan gum as the second coating, and wheat (W) and corn (C) flours in the ratio of 1:1 or 2:1 as the last coating. In terms of the fillet quality, the following results were obtained in the analyses conducted before frying. The lowest pH found was 6.25 in zein-containing samples and 6.30 in guar-containing samples. The effects of the last coatings on pH were unimportant (P > 0.05). The lowest thiobarbituric acid levels found were 2.07 mg kg in the fillets coated with casein mixture, 2.44 mg kg in the fillets coated with xanthan gum, and 2.25 mg kg in the fillets coated with W:C flour mixture in the ratio of 2:1. The lowest total volatile basic nitrogen levels found were18.06 mg 100 g in the fillets coated with casein mixture, 18.62 mg 100 g in the fillets coated with xanthan gum, and 18.47 mg 100 g in the fillets coated with W:C flour mixture at 1:1 ratio. In the sensorial analysis, the coated samples were much more preferred than those not coated. As a result of the effects of all the materials, the coating layers on the meat surface provided more resistance against mass transfer during storage.
Introduction : Quality attributes of fish flesh, including food safety, organoleptic features, nutritional quality and aptitude to industrial transformation, influence consumption and acceptability of fish as food. Fish sensorial changes and texture properties are closely linked to freshness. Along with ante mortem muscle biochemistry, postmortem biochemical processes are directly linked to final quality attributes. The understanding of postmortem mechanisms is a prerequisite for an accurate control of the quality of commercialized fish by the identification of objective markers or indicators. Postmortem tenderization is one of the most important quality attributes of fish muscle. Loss of freshness is due to a complex combination of biochemical, chemical and physical processes, and is followed by muscle spoilage due to microbiological contamination. Autolytic modifications include protease action on proteins and connective tissue, and also fat hydrolysis. Tenderization is enzymatic in nature; physio-chemical conditions (pH, osmotic pressure) may modulate the proteolytic action of endogenous enzymes. Our studies have given additional information regarding the proteolytic mechanisms involved in postmortem disorganization of fish muscle by characterizing the myofibrillar components undergoing proteolysis 1-3 as well as by studying the involved proteases especially calpains 4;5 and their effects in vitro on myofibrillar proteins 6. The knowledge of the relationship between this disorganization, loss of freshness, and textural degradation should be improved in order to identify potential freshness indicators, and develop methods to improve quality. The purpose of this paper is to give a broad overview of quality changes in fish and the possible mechanisms responsible.
These experiments were conducted to examine ultrastructural changes in longissimus from normal and callipyge lamb during 14 d of postmortem storage at 4 degrees C. Six crossbred ewe lambs (1/2 Dorset x 1/2 Romanov) were grain-fed and slaughtered at approximately 250 d of age. Leg conformation score was the basis for classifying carcasses into normal and callipyge. The normal and callipyge longissimus had mean Warner-Bratzler shear force of 2.8 (2.7, 2.4, and 3.4) and 9.0 (12.2, 6.9, and 7.9) kg, respectively, after 14 d of postmortem storage. The results of transmission electron microscopy demonstrated ultrastructural changes, including sarcolemma detachment, loss of myofibril lateral attachments, and I-band breaks in normal longissimus. Detachment of sarcolemma from myofibrils occurred in both phenotypes, but it was delayed by several days in callipyge longissimus. Thus, the sarcolemma detachment seems not to contribute significantly to postmortem tenderization. The endomysium of both phenotypes did not change with postmortem storage. In normal longissimus, the percentage of fractured I-bands increased from 0% at d 1 to 11% at d 3 (P<.05) and did not change between 3 and 14 d (15%) postmortem (P>.05). However, postmortem storage did not affect (0 to 3%) the frequency of the I-band breaks in the callipyge longissimus (P>.05). Therefore, the break in the I-band region in postmortem muscle is a change that is associated with postmortem tenderization. We conclude that the major factor responsible for the toughness of meat from callipyge longissimus is the postmortem stability of myofibrils.
We used a culture-independent approach, namely, thermal gradient gel electrophoresis (TGGE) analysis of ribosomal sequences amplified directly from community DNA, to determine changes in the structure of the microbial community following phenol shocks in the highly complex activated sludge ecosystem. Parallel experimental model sewage plants were given shock loads of chlorinated and methylated phenols and simultaneously were inoculated (i) with a genetically engineered microorganism (GEM) able to degrade the added substituted phenols or (ii) with the nonengineered parental strain. The sludge community DNA was extracted, and 16S rDNA was amplified and analyzed by TGGE. To allow quantitative analysis of TGGE banding patterns, they were normalized to an external standard. The samples were then compared with each other for similarity by using the coefficient of Dice. The Shannon index of diversity, H, was calculated for each sludge sample, which made it possible to determine changes in community diversity. We observed a breakdown in community structure following shock loads of phenols by a decrease in the Shannon index of diversity from 1.13 to 0.22 in the noninoculated system. Inoculation with the GEM (Pseudomonas sp. strain B13 SN45RE) effectively protected the microbial community, as indicated by the maintenance of a high diversity throughout the shock load experiment (H decreased from 1.03 to only 0.82). Inoculation with the nonengineered parental strain, Pseudomonas sp. strain B13, did not protect the microbial community from being severely disturbed; H decreased from 1.22 to 0.46 for a 3-chlorophenol-4-methylphenol shock and from 1.03 to 0.70 for a 4-chlorophenol-4-methylphenol shock. The catabolic trait present in the GEM allowed for bioprotection of the activated sludge community from breakdown caused by toxic shock loading. In-depth TGGE analysis with similarity and diversity algorithms proved to be a very sensitive tool to monitor changes in the structure of the activated sludge microbial community, ranging from subtle shifts during adaptation to laboratory conditions to complete collapse following pollutant shocks.
We investigated the effects of frozen acidic electrolyzed water (AcEW) on lettuce during storage in a styrene-foam container. The lettuce was kept at 2 to 3 degrees C for 24 h. Populations of aerobic bacteria associated with lettuce packed in frozen AcEW were reduced by 1.5 log CFU/g after storage for 24 h. With frozen tap water, no microorganism populations tested in this study were reduced. A frozen mixture of AcEW and alkaline electrolyzed water (AlEW) also failed to reduce populations of microorganisms associated with lettuce. Although chlorine gas was produced by frozen AcEW, it was not produced by the AcEW-AlEW mixture. This result indicates that the main factor in the decontaminative effect of frozen AcEW was the production of chlorine gas. Accordingly, low-temperature storage and decontamination could be achieved simultaneously with frozen AcEW during distribution.
Acidic electrolyzed water (AcEW) was used as frozen AcEW (AcEW-ice) for inactivation of Listeria monocytogenes and Escherichia coli O157:H7 on lettuce. AcEW-ice was prepared from AcEW with 20, 50, 100, and 200 ppm of available chlorine by freezing at -40 degrees C and generated 30, 70, 150, and 240 ppm of chlorine gas (Cl2), respectively. The AcEW-ice was placed into styrene-foam containers with lettuce samples at 20 degrees C for 24 h. Although AcEW-ice generating 30 ppm Cl2 had no effect on L. monocytogenes cell counts, AcEW-ice generating 70 to 240 ppm of Cl2 significantly (P < 0.05) reduced L. monocytogenes by ca. 1.5 log CFU/g. E. coli O157:H7 cell counts were reduced by 1.0 log CFU/g with AcEW-ice generating 30 ppm of Cl2. AcEW-ice generating 70 and 150 ppm of Cl2 reduced E. coli O157:H7 by 2.0 log CFU/g. Further significant reduction of E. coli O157:H7 (2.5 log CFU/g) was demonstrated by treatment with AcEW-ice generating 240 ppm of Cl2. However, treatment with AcEW-ice generating 240 ppm of Cl2 resulted in a physiological disorder resembling leaf burn. AcEW-ice that generated less than 150 ppm of Cl2 had no effect on the surface color of the lettuce. AcEW-ice, regardless of the concentration of the emission of Cl2, had no effect on the ascorbic acid content in the lettuce. The weight ratio of lettuce to AcEW-ice required was determined to be over 1:10. The bactericidal effect of AcEW-ice appeared within the first 2 h. The use of AcEW-ice provides simultaneously for low temperature storage and inactivation of bacteria.
In the present study the combined effect of gamma irradiation (1, 3 and 5 kGy) and storage at two temperatures: refrigeration (+4 °C) and frozen (−18 °C), on the shelf-life extension of fresh shrimp meat was investigated. The study was based on microbiological and physicochemical changes occuring in the shrimp samples. Total volatile base nitrogen values and trimethylamine values for irradiated shrimp samples were significantly lower than non-irradiated samples at both storage temperatures, and the rate of decrease was more pronounced in samples irradiated at the higher dose (p<0.05). Thiobarbituric acid values for irradiated shrimp samples were significantly higher than non-irradiated samples at both storage temperatures (p<0.05). pH values of shrimp samples were affected significantly by both irradiating dose and storage temperatures (p<0.05). Microbial counts for non-irradiated shrimp samples were higher than the respective irradiated samples at both storage temperatures (p<0.05). The results revealed that irradiation at high dose (5 kGy) might enhance lipid oxidation, although the growth of microorganisms and protein oxidation was inhibited.
Canned tuna meat was inoculated with Raoultella ornithinolytica at a level of 2.0 log CFU/g (low) or 5.0 log CFU/g (high) and stored at 4, 15, 25, or 37 °C to investigate bacterial growth and formation of total volatile base nitrogen (TVBN) and histamine in canned tuna meat. R. ornithinolytica grew rapidly in all samples stored at temperature above 15 °C regardless of the inoculation levels. The histamine contents quickly increased to higher than 50 mg/100 g within 12 h in the low inoculated samples and stored at 37 °C as well as in those inoculated with the high level and stored at 25 °C or higher. However, growth of R. ornithinolytica and its histamine production were inhibited when samples were stored at 4 °C. The TVBN contents in all samples were all below 30 mg/100 g during storage even when the levels of histamine in some samples increased to greater than 50 mg/100 g. Therefore, canned tuna meat was a good substrate for histamine formation by bacterial histidine decarboxylation at elevated temperatures (> 15 °C) when it is contaminated with R. ornithinolytica.
The objective of this study was to evaluate physicochemical properties and bactericidal activities of acidic electrolyzed water (AEW) used or stored at different temperatures on shrimp. Three independent experiments were carried out. The first experiment was to evaluate the physicochemical properties and bactericidal activities of AEW used at three different temperatures (4, 20, 50°C) against food-borne pathogens (Listeria monocytogenes and Vibrio parahaemolyticus) contamination on cooked shrimp at 1 or 5min; the second one was to monitor the bactericidal activity of AEW used at two temperatures (20, 50°C) against total aerobic bacteria on raw shrimp at 5min by conventional plate count method and PCR–DGGE method; the last one was to examine the physicochemical properties and bactericidal activities of AEW (AEW1, AEW2) stored at two temperatures (−18, 25°C) for 30d against total aerobic bacteria on raw shrimp at 2min. Results showed that AEW used at 50°C showed the best bactericidal activity, leading to a log reduction of 3.11 for V. parahaemolyticus, 1.96 for L. monocytogenes and 1.44 for total aerobic bacteria at 5min, respectively. Conventional plate count and PCR–DGGE (denaturing gradient gel electrophoresis) study further suggested that the bactericidal activity of AEW used at 50°C was higher than at 20°C. The loss of bactericidal activity of AEW stored at −18°C was less than that of stored at 25°C, and the ORP and ACC decreased more slowly than those of stored at 25°C. However, the ORP and ACC of AEW used at 50°C showed a remarkably faster decrease than that of used at 20°C. We suggest using AEW at 50°C to enhance bactericidal activity and storing at −18°C to keep the content of ACC and the bactericidal activity.
Sea bream, Sparus aurata L., specimens were studied in pre-rigor (3h) and during the following post-mortem days: 1, 5, 10, 15 and 22. Muscle and textural parameters were evaluated on 6 specimens/stage. Structural results showed scarce fibre-to-fibre detachment on pre-rigor, which increased during the post-mortem degradation. Ultrastructural changes revealed rapid muscle degradation. In pre-rigor myofibrils were detached to both sarcolemma and endomysium. Intermyofibrillar spaces increased and some mitochondriae and sarcoplasmic reticulum were swollen. After 1 day, the sarcolemma appeared occasionally disrupted and the interfibrillar spaces increased. From 5 to 10 days, the I-band and Z line presented some alterations, although these were more severe at 15–22 days. Thus, in these two last stages, loss of I-band, Z line and actin filaments was observed, that coincides with the alteration of the hexagonal arrangement in these advanced stages. Also, the fragmentation of myofibrils increased from 5 to 10 days on. Sarcolemma and endomysium were gradually disrupted throughout the post-mortem stages with total loss at 22 days. Consequently, the interfibrillar spaces increased at last stages. Autophagic mechanisms increased from 5 days on, with an intense destruction of all the intracytoplasmic organelles. Textural parameters decreased from pre-rigor until 5–10 days, mainly associated to detachment of myofibers to sarcolemma-endomysium.
This report investigated the melanosis-inhibiting properties of crude water soluble extract from the base and fruiting body waste of an edible mushroom (Flammulina velutipes) containing 9.13±2.03mg/mL 2-thiol-l-histidine-betaine (ergothioneine, ESH). Immersion of live full-grown black tiger shrimp (Penaeus monodon) and Pacific white shrimp (Litopenaeus vannamei) in a 0.5% w/v solution of mushroom extract for 1h significantly decreased polyphenoloxidase (PPO) activity in shrimp hemolymph and expression of the prophenoloxidase (proPO) gene in hemocytes. Consequently, the development of melanosis in the treated shrimp during ice storage was prevented. Treatment with a 0.05% w/v solution of sodium sulfite and 4-hexyl-1,3-benzenediol had a similar effect. Enzyme assays showed that ESH is a non-competitive inhibitor. It is proposed that ESH possibly interacts directly with Cu2+ at the putative binding sites of PPO and proPO, based on copper-chelating activity analyses, thus preventing melanosis in the shrimp. This study indicated that application of ESH-rich F. velutipes mushroom extract from trimming waste is an effective natural alternative to synthetic melanosis-inhibiting agents to prevent postmortem melanosis in shrimp.
High-pressure processing (HPP) is a technology of growing interest for food preservation, due to its ability to control the activity of degradative enzymes. The effect of three variables (pressure levels of 100, 250, and 400 MPa; pressure holding times of 0, 5, 15, and 30 min; and pressurization rates of 8 and 14 MPa/s) on the activity of the enzymes acid phosphatase, cathepsins (B and D), lipase, and calpains was studied using sea bass fillets as a case study model. Additionally, the effect of HPP on sarcoplasmic proteins was studied by SDS-PAGE and isoelectric focusing electrophoreses. The increase in pressure level and holding time decreased the protein concentration in sarcoplasmic extracts, and also the activity of calpains. As compared to nontreated samples, acid phosphatase activity was lower at 400 MPa, and for cathepsin D lower activities were observed at 100 and 400 MPa. The increase in pressurization rate increased the activity of cathepsin D, lipase, and calpains, although it was not always significant. In contrast, cathepsin B and lipase activities were less affected by HPP treatments. Electrophoresis separation of sarcoplasmic proteins showed that the intensity of many protein bands changed mainly due to pressure level and holding time. The results of this study suggest that HPP causes lysosomes disruption and also denaturation, aggregation, and fragmentation of sarcoplasmic proteins, and this evidence might be related to the decrease in enzymes activity especially at 400 MPa. In conclusion, HPP can be a potential tool to control the activity of degradative enzymes, which might prevent the softening of sea bass muscle due to autolytic reactions.
The use of ozonised slurry ice was investigated as a new refrigeration system for the storage of farmed turbot (Psetta maxima). With this purpose in mind, an ozone generator device was coupled to a slurry ice system working subzero at −1.5 °C. The ozone concentration was adjusted to a redox potential of 700 mV, and the slurry ice biphasic mixture was prepared at a 40% ice/60% water ratio and 3.3% salinity. Certain biochemical parameters indicative of fish freshness, such as the rate of nucleotide degradation or TMA-N formation, were not significantly affected by the presence of ozone in the slurry ice mixture. However, storage in ozonised slurry ice significantly slowed down the mechanisms responsible for lipid hydrolysis and lipid oxidation in farmed turbot. Storage in ozonised slurry ice also led to significantly (p
Slurry ice, a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature, was evaluated as a new chilled storage method for whole European hake (Merluccius merluccius), a gadoid fish species of remarkable commercial interest, and this method was compared with a control batch stored for 19 days in traditional flake ice. The results obtained in the sensory analysis indicated a significant extension of shelf-life – from 5 days (flake ice batch) to 12 days (slurry ice batch) – in the latter batch, mainly deriving from a better maintenance of both external and fresh odour, the appearance of the gills and consistency. The slurry ice batch exhibited a significantly lower increase in pH as compared to the flake ice batch, this indicating a better control of the former over alkalinising microflora. Thus, significantly lower counts of total aerobes and proteolytic bacteria were also attained in hake muscle stored in slurry ice, microbial numbers reaching average differences of ≈1 log unit before 12 days of storage and above 2 or 3 log units, respectively, when this period was extended up to 19 days. The formation of total volatile base-nitrogen and trimethylamine were also significantly lower in the slurry ice batch after 12 days of storage. According to the parameters assessed, storage of European hake in slurry ice extends the shelf-life of this species and allows a better maintenance of sensory and microbiological quality.
The freshness of large yellow croaker (Pseudosciaena crocea) fillets was evaluated over 20 days of chilled storage under vacuum packing. The physicochemical properties [pH, K-value, thiobarbituric acid (TBA), texture profile analyses (TPA), colour], microbiological properties [total viable count, (TVC)], sensory attributes, transcriptomics (levels of transcripts coding for cathepsin L) and functional properties of proteins [emulsion activity (EA) and emulsion stability (ES)] were assessed at 0, 5, 10, 15 and 20 days of storage. We also investigated the effect of the storage time on fish muscle proteome in large yellow croaker using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption ionisation time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS). The parameters that were the most sensitive to storage duration were colour (C*ab), TPA (springiness, chewiness and resilience), pH, K-value, TVC, levels of transcripts coding for cathepsin L, EA, ES and sensory attributes. The three altered proteins (spots 3010, 5108 and 5109) were successfully identified. Therefore, these parameters might be considered suitable indicators for evaluating the freshness of large yellow croaker fillets during chilled storage under vacuum packing.
Cross-sections of cooked muscle were prepared using a vibrating microtome. Average fiber cross-sectional area was measured by confocal scanning laser microscopy and image analysis. Fiber cross-sectional area significantly correlated with sensory perception of firmness (r = -0.91, p < 0.01). Sensory firmness decreased with increasing fish species fiber cross-section.
Textural differences in cooked fish muscle tissues, according to species, were demonstrated quantitatively by acquiring fresh tissue samples of five species, cooking them under specific conditions, measuring the common physical properties of each (drip, residual weight, fumness, cohesiveness, penetration, fiber volume, fiber diameter, and fiber length) and scoring them in a range of −1.2 to −1.8 for skipjack to 1.0 to 2.0 for channel rock fish using discriminant analysis.
Atlantic salmon (Salmo salar) fillets were stored on ice for a maximum of 14 d to determine which muscle structures are associated with changes in texture and rigor. Texture was measured as shear force and the changes correlated with structural alterations. Texture decreased significantly within 24 h in parallel with loss of attachment of muscle fibers. Loss of rigor stiffness by 5 d was associated with myofiber detachment from the myocommata. These results show that fillet texture depends on several distinct structures and events, initially including breaks in the cell cytoskeleton and loss of fiber-fiber attachment and later breaks in the connective tissue and fiber detachment from the myocommata.
The storage of deepwater pink shrimp (Parapenaeus longirostris) in modified atmosphere was studied. Two gas mixtures were tested (40% CO2/30% O2/30% N2 and 45% CO2/5% O2/50% N2), combined with sulfites-based pretreatment, in comparison with air storage. The quality of shrimp was evaluated by sensory (black spot presence) and chemical analyses (pH value and nucleotides breakdown products). Generally, both atmospheres preserved the shrimp quality up to 9 d compared with 4 to 7 d of ice storage (only with pretreatment), although it seems that atmosphere containing 45% CO2/5% O2/50% N2 was the most effective.
Cooked muscle tissue of five fish species were observed by optical and scanning electron micrography. Species with firm texture had thin muscle fibers with considerable heat-coagulating material between them; species having soft texture had thick muscle fibers with little heat-coagulating material. When the cooked muscles were compressed by a Texturometer, muscle fibers of the species having firm texture slid or shifted over one another to a lesser extent than those of species with soft texture. The heat-coagulating material seemed to obstruct the displacement of the fibers. The diameter and mobility of muscle fibers are determinative of firmness of fish muscle tissue.
Denaturing gradient gel electrophoresis (DGGE) profiles of PCR amplified V3 regions of 16S rRNA genes were used to assess the diversity in enrichment cultures with methane as the only carbon and energy source. The enrichments originated from two agricultural soils. One was a sandy soil with low (10%) organic content, the other an organic soil with approximately 50% organic content. DGGE provided a fast evaluation of the distribution of amplifiable sequence types indicating that specific bacterial populations had been enriched from each soil. The DGGE profiles revealed a broader range of amplified V3 fragments in the community derived from organic soil than from sandy soil. Fragments from 19 individual DGGE bands were sequenced and compared with 27 previously published 16S rRNA gene sequences. The sequences confirmed the high diversity with the presence of different methylotrophic populations in each enrichment. No affiliation was found with type I methanotrophs, instead type II methanotroph sequences were found in the enrichments from both soil types. Some of the fragments from the organic soil enrichment were not affiliated with methylotrophs. Most of the sequences clustered distantly on a branch within the α-Proteobacteria. These facts suggested that previously undescribed methylotrophs are abundant in methane enrichments from agricultural soil.
Among different fish slices used for sashimi preparation, tuna is the most popular and preferable fish type for Taiwanese people. To improve the hygienic quality of fish slices, electrolyzed (EO) water containing 10, 50, and 100 mg/L chlorine, was used in combination with CO gas treatment. Effect of different treatment on aerobic plate count (APC), volatile basic nitrogen (VBN), K value, and Hunter L*, a*, b* values of yellow-fin tuna steak during storage (4 °C and −20 °C) were evaluated. It was found that APC, VBN, and K values increased with storage time for all treatment. Except for K value, APC and VBN of tuna steak treated with the combination of more than 50 mg/L chlorine EO water and CO gas had the lowest value after 8 d of refrigerated storage. Hunter a* value of tuna steak treated with only CO gas was the highest, followed by those treated with EO water and CO gas. These results demonstrated that EO water containing 50 mg/L chlorine combined with CO gas treatment in tuna fish steak would be an effective method for enhancing the hygienic quality and freshness for tuna meat and extending refrigerated storage time. Tuna treated with EO water containing 100 mg/L chlorine and CO gas combination had the lowest APC immediately after treatment and reduced further to below detection limit after 1 mo frozen storage at −20 °C.
Melanosis and quality changes of Pacific white shrimp (Litopenaeus vannamei) treated with 0.1% green tea extract (GTE) in combination with ascorbic acid (AA) at different levels (0%, 0.005%, and 0.01%)
were monitored during iced storage of 12days. Based on in vitro study, 0.1% GTE inhibited polyphenoloxidase (PPO) from cephalothorax of Pacific white shrimp by 60.2%. Nevertheless, 0.1%
GTE in combination with 0.01% AA exhibited the greater PPO inhibitory activity (93.0%) (P < 0.05). When shrimp treated with 0.1% GTE in combination with AA (0.005 or 0.01%; GTE + AA), the increase in psychrophilic
bacteria and spoilage microorganisms including H2S- producing bacteria and enterobacteriaceae were retarded to a higher extent, in comparison with the control and those treated
with 1.25% sodium metabisulfite (SMS; P < 0.05). The coincidental lowered rates of increase in pH, total volatile base content and thiobarbituric acid reactive substances
were obtained in the shrimp treated with GTE + AA (P < 0.05). Additionally, shrimp treated with GTE + AA had the lower melanosis score but higher score for color, odor, taste,
flavor, and overall likeness, compared with the control and those treated with SMS (P < 0.05). Generally, AA at levels of 0.005% and 0.01% showed a similar synergist effect with GTE on both melanosis inhibition
as well as retardation of quality loss of shrimp.
KeywordsGreen tea extract-Ascorbic acid-Pacific white shrimp-Quality-Melanosis
European sea bass (Dicentrarchus labrax) is one of the finfish species preferred by the consumer, who requires fish freshness to be maintained during distribution and retail. For this reason, the purposes of this study were to define: the shelf life at three storage temperatures (−0.5, 4.8 and 16.5 °C) by applying both chemical (TVB and TBA assays) and olfactometric (e-nose) method; the actual time–temperature exposure conditions during marketing; the prediction of remaining shelf life in the commercial chain, on the basis of time–temperature history data and on appropriate integration routine. Shelf life study revealed the efficacy of chemical markers and electronic nose in describing the freshness decay and in defining a freshness threshold. Freshness of sea bass was kept for about 8 days for fish preserved in melting ice (−0.5 °C), 4 days at 4.8 °C and about 1 day at 16.5 °C. When fresh European sea bass was purchased, 9 out of 10 times the remaining shelf life was more than 55% at an average temperature of 1.19 °C. Therefore, the freshness of fish can be assured for 3–4 days in commercialization. A joint effort (sales point management and consumer advertising) could reduce the exposure temperature by 1–2 °C and justify an extension of the shelf life to 2–3 days after purchase.
This study investigated efficacy of electrolyzed oxidizing water (EO water) and ice (EO ice) treatments in reducing histamine-producing bacteria (Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae, Morganella morganii and Proteus hauseri) on food contact surfaces (ceramic tile and stainless steel) and fish skin (Atlantic salmon and yellowfin tuna). Soaking ceramic tile and stainless steel in EO water (50 ppm chlorine) for 5 min inactivated inoculated bacteria on the surface (>0.92 to >5.4 log CFU/cm2 reductions). E. cloacae, K. pneumoniae and P. hauseri did not survive well on fish skin. Soaking salmon skin in EO water (100 ppm chlorine) for 120 min resulted in 1.3 and 2.2 log CFU/cm2 reductions of E. aerogenes and M. morganii, respectively. A treatment of EO ice (100 ppm chlorine) for 24 h was capable of reducing E. aerogenes and M. morganii on tuna skin by 2.4 and 3.5 log CFU/cm2, respectively. EO water and EO ice can be used as post-harvest treatments for reducing histamine-producing bacteria on food contact surfaces and fish skin.
Freshness assessment of European eel (Anguilla anguilla) stored in ice and in boxes without ice at 3 ± 1 °C was assessed by sensory, chemical (total volatile basic nitrogen (TVB-N), thiobarbituric values (TBA), peroxide value (PV), free fatty acid (FFA), and pH) and microbiological (total viable counts, TVC) methods. The limit for sensory acceptability of eel stored in ice was ∼12–14 days, and ∼5–7 days at 3 ± 1 °C. TVB-N level of about ≥10 mg TVB-N 100 g−1 flesh could be regarded as the limit of acceptability. PV values and the release of FFA increased during storage in ice and at 3 ± 1 °C but the increases were greater at 3 ± 1 °C. Values of pH showed no statistically significant (P > 0.05) changes for eel stored in ice and at 3 ± 1 °C. Water losses of fillets stored at at 3 ± 1 °C were higher (P < 0.05) than those stored in ice. TBA values were found to fluctuate under both storage conditions. This study shows that sensory analysis of eel correlated well with microbiological analysis. The acceptability of eel decreased as TVB-N, FFA, PV and TVC values increased.
Chemical, microbiological and sensorial changes of striped catfish (Pangasius hypophthalmus) slices treated without and with tannic acid (100 and 200 mg/kg) were determined during 15 days of storage at 4 °C in air and under modified atmospheric packaging (MAP, 60% N2/35% CO2/5% O2). The slices consisted of 9.2 g lipid/100 g and the lipid contained 64.55% unsaturated fatty acids and 33.87% saturated fatty acids. During the storage, the sample treated with 200 mg/kg tannic acid and stored under MAP (M2) had the lowest peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) with the coincidental lowest non-haem iron content, indicating the retarded lipid oxidation. Fourier transform infrared (FTIR) spectra indicated the formation of primary oxidation products and free fatty acids in M2 sample after 15 days. Conversely, these compounds were found at lower contents in the control samples kept in air without tannic acid treatment (A0), suggesting that the deterioration was more advanced. Myosin heavy chain of A0 was degraded by 17.85% after 15 days of storage, whereas no change was noticeable in M2, compared with the fresh sample (F). Based on microbiological acceptability limit (107 cfu/g), the shelf-life of A0 and M2 was estimated to be 3 and 15 days, respectively. M2 had the acceptable scores for all sensory attributes up to 15 days, while A0 was acceptable when stored for 9 days. Therefore, tannic acid exhibited a synergistic effect with MAP on retarding lipid oxidation and microbial growth, thereby increasing the shelf-life of striped catfish slices during refrigerated storage.
Electrolyzed oxidizing (EO) water has been regarded as a new sanitizer in recent years. Production of EO water needs only water and salt (sodium chloride). EO water have the following advantages over other traditional cleaning agents: effective disinfection, easy operation, relatively inexpensive, and environmentally friendly. The main advantage of EO water is its safety. EO water which is also a strong acid, is different to hydrochloric acid or sulfuric acid in that it is not corrosive to skin, mucous membrane, or organic material. Electrolyzed water has been tested and used as a disinfectant in the food industry and other applications. Combination of EO water and other measures are also possible. This review includes a brief overview of issues related to the electrolyzed water and its effective cleaning of food surfaces in food processing plants and the cleaning of animal products and fresh produce.
The safety of electrolyzed seawater was evaluated by measuring the production rate of organic halogen compounds and the occurrence of reverse mutations. Aquaculture feedwater and wastewater were collected from a fish-culturing facility, and available chlorine of approximately 1.0 mg/L was generated to ensure a disinfectant effect. More than 90% of the generated organic halogen compounds were bromoform. The amount of bromoform was far less than the reference values for drinking water standards in Japan and the U.S., provided that the electrolyzation was performed within the range of normal use. The reverse mutation assay of electrolyzed seawater showed no mutagenicity. Electrolyzed seawater with available chlorine at an adequate level for disinfection can be used safely and effectively in various aspects of aquaculture.
Melanosis of Pacific white shrimp (Litopenaeus vannamei) subjected to freeze–thawing with different thawing methods and various cycles were monitored during subsequent refrigerated storage (4 °C) up to 4 days. Melanosis score was lower in Pacific white shrimp thawed at 4 °C, compared with that found in samples thawed at room temperature or using tap water. Polyphenol oxidase (PPO) activity increased as freeze–thaw cycles increased (P < 0.05). Enhanced PPO activity was most likely associated with increased melanosis. Pacific white shrimp treated with catechin (0.05%, 0.1% and 0.2% (w/v)) or ferulic acid (1%, 2% and 3% (w/v)) and subjected to freeze–thawing with various cycles showed the retarded melanosis during the subsequent refrigerated storage of 4 days, compared with the control (P < 0.05). Treatment of shrimp with both phenolic compounds could impede the growth of psychrophilic bacteria and the spoilage as evidenced by the lowered psychrophilic bacteria count and total volatile base content (TVB). Sample treated with 0.2% catechin or 3% ferulic acid also exhibited the retarded lipid oxidation during the subsequent refrigerated storage, compared with the control (P < 0.05). Thus, either catechin or ferulic acid could be used as the potential additive to lower melanosis of shrimp with prior freeze–thawing.
Commercial-sized meagre fillets were stored on ice at 4 °C for 18 days, in order to evaluate the loss of quality and freshness that occurs over this period of time. Physicochemical (pH, thiobarbituric acid (TBA), total volatile basic nitrogen (TVBN), trimethylamine (TMA), water activity, water-holding capacity, colour, texture and fatty acid profile), sensory and microbiological analyses were carried out at 0, 4, 7, 11, 14 and 18 days of storage. As part of the sensory analysis, attributes associated with fillet appearance, odour and texture were examined. Variations in pH, TBA, TVBN and TMA were observed throughout the storage period, although only TBA displayed a significant correlation with time (r = 0.96). L∗ and b∗ values increased, and the chroma and hue values decreased, reflecting the colour changes experienced by the fillets over time. With regards to the texture profile, hardness was significantly correlated with time (−0.68). All the sensory analysis attributes exhibited significant variations and correlations close to 1.00 with storage time, which is a reflection of the fillets’ loss of freshness. The correlation coefficients between aerobic mesophilic and psychrophilic bacteria, enterobacteria and coliform counts on the one hand and storage time on the other were also very high (0.99–1.00). A regression analysis using the acceptability limit set by the ICMSF standard (1986) for total aerobic mesophilic counts (7 log cfu/g) yielded a shelf-life for meagre fillets of 9 days. The TBA, sensory and microbiological analyses displayed very strong correlations with storage time, and they may be considered suitable indicators for evaluating meagre fillet spoilage during refrigerated storage.
Sea bass (Dicentrarchus labrax L.) has been widely farmed in the last decade. In order to a better understanding of the final quality of this species, muscle cellularity and quality parameters of the flesh were studied on 14 specimens of wild and 11 farmed Atlantic sea bass, at approximate commercial size (weight 350 g, length 32 cm). White muscle cellularity was evaluated by means of the following parameters: number and diameter of muscle fibres, as well as the muscle fibre size distribution, throughout the total cross-section of the flesh. To ascertain the flesh quality, several physico-chemical parameters (moisture, protein, total fat, fatty acids, hydroxyproline, collagen and pH) were analyzed, and textural mechanical properties (hardness, springiness, chewiness, cohesiveness, gumminess) were determined objectively with a texturometer.
Summary This work investigates how the treatment of thawed deepwater pink shrimp (Parapenaeus longirostris) with several melanosis-inhibiting formulations, affects the quality of the shrimp during chilled storage. Formulations were as follows: a formulation containing 4-hexylresorcinol (0.1 and 0.05%), in combination with organic acids and chelating agents, a commercial formula based on sulphites, and a mixture of gluconic acid and commercial sulphites. No noticeable differences were observed for both trimethylamine and total volatile bases during chilled storage. pH evolution was irrespective of the treatment condition. Microbial load enlarged after the sixth day of chilled storage. Higher total bacteria counts were associated with the control and sulphite treatment conditions, while lactic acid bacteria growth seemed to be favoured under formulations based on 4-hexylresorcinol. The appearance of melanosis occurred more rapidly in control shrimp or in shrimp treated with commercial sulphites. 4-hexylresorcinol formulations preserved the quality of thawed shrimp and could replace traditional sulphites.
The purpose of this manuscript is to present a brief review of the biochemical basis for longissimus toughening and tenderization processes. Also, to explore the potential technologies that can be developed based on this knowledge to reduce variation in tenderness, thus, improving consumer acceptance of meat. Results suggest that after slaughter longissimus has low to intermediate shear force values (probably tender). Rigor development-induced changes increase its shear force. Maximum toughness is observed between 12 to 24 h post mortem. The toughening process seems to occur equally in all carcasses. Post-mortem storage at refrigerated conditions tenderizes longissimus. Post-mortem tenderization is caused by enzymatic degradation of key myofibrillar and associated proteins. The function of these proteins is to maintain the structural integrity of myofibrils. Current data indicates that μ-calpain is responsible for degradation of these proteins. Unlike the toughening process, there exists a large variation in the rate and extent of tenderization which is responsible for variation in tenderness at the consumer level. Potential strategies for the control of the variation in meat tenderness are discussed.
Biochemical processes and structural changes that occur in muscle during the first 24h postmortem play a great role in the ultimate quality and palatability of meat and are influenced by the chilling processes that carcasses are subjected to after slaughter. For beef and lamb, employing chilling parameters that minimize cold shortening is of greatest importance and can be best addressed by ensuring that muscle temperatures are not below 10°C before pH reaches 6.2. For pork, because of the impact of high muscle temperatures and low pH on the development of pale, soft, and exudative (PSE) pork, a more rapid chilling process is needed to reduce PSE with the recommended internal muscle temperature of 10°C at 12h and 2-4°C at 24h. Spray chilling, a system whereby chilled water is applied to carcasses during the early part of postmortem cooling, is used to control carcass shrinkage and to improve chilling rates through evaporative cooling. Delayed chilling can be used to reduce or prevent the negative effects of cold shortening; however, production constraints in high-volume facilities and food safety concerns make this method less useful in commercial settings. Electrical stimulation and alternative carcass suspension programs offer processors the opportunity to negate most or all of the effects of cold shortening while still using traditional chilling systems. Rapid or blast chilling can be an effective method to reduce the incidence of PSE in pork but extreme chilling systems may cause quality problems because of the differential between the cold temperatures on the outside of the carcass compared to the warm muscle temperatures within the carcass (i.e., muscles that are darker in color externally and lighter in color internally).
Post-mortem changes in two calcium-dependent proteases, their inhibitor, myofibril fragmentation index (MFI) and collagen (amount and solubility) were studied. Whereas the activity of high Ca(++)-requiring calcium-dependent protease (CDP-II) remained nearly constant throughout post-mortem storage, there was a progressive decrease in the activities of low Ca(++)-requiring calcium-dependent protease (CDP-I) and their specific inhibitor, with the inhibitor being the most susceptible to post-mortem storage. Results indicated that the greatest changes in MFI occur within the first 24 h of post-mortem storage. There were no detectable changes in either total or soluble collagen content with post-mortem storage. Hence, it was concluded that improvement in tenderness resulting from post-mortem storage must be derived from changes in the myofibrils and since CDP-I activities paralleled the myofibrillar changes, it seems reasonable to suggest that CDP-I, not CDP-II, plays an important role in the fragmentation of myofibrils and consequently in improvement of meat tenderness resulting from post-mortem storage.
The inhibitory effect of mimosine on polyphenoloxidase (PPO) from the cephalothorax of Pacific white shrimp (Litopenaeus vannamei) was studied. Mimosine showed inhibitory activity toward PPO from white shrimp with an apparent molecular weight of 210 kDa as evidenced by the decrease in the activity staining band, as compared to the control. An inhibition kinetic study revealed that mimosine exhibited the mixed type reversible inhibition on PPO from white shrimp with a Ki value of 3.7 mM. Mimosine showed copper (Cu2+) reduction and chelating capacity in a dose dependent manner. Mimosine could react with the intermediate browning product, thereby rendering lower red-brown color formation. Therefore, mimosine could inhibit PPO by different modes of inhibition and could be used to prevent melanosis formation in Pacific white shrimp.
This study investigated the efficacy of sanitized ice for the reduction of bacteria in the water collected from the ice that melted during storage of whole and filleted Tilapia fish. Also, bacterial reductions on the fish fillets were investigated. The sanitized ice was prepared by freezing solutions of PRO-SAN (an organic acid formulation) and neutral electrolyzed water (NEW). For the whole fish study, the survival of the natural microflora was determined from the water of the melted ice prepared with PRO-SAN and tap water. These water samples were collected during an 8 h storage period. For the fish fillet study, samples were inoculated with Escherichia coli K12, Listeria innocua, and Pseudomonas putida then stored on crushed sanitized ice. The efficacies of these were tested by enumerating each bacterial species on the fish fillet and in the water samples at 12 and 24 h intervals for 72 h, respectively. Results showed that each bacterial population was reduced during the test. However, a bacterial reduction of < 1 log CFU was obtained for the fillet samples. A maximum of approximately 2 log CFU and > 3 log CFU reductions were obtained in the waters sampled after the storage of whole fish and the fillets, respectively. These reductions were significantly (P < 0.05) higher in the water from sanitized ice when compared with the water from the unsanitized melted ice. These results showed that the organic acid formulation and NEW considerably reduced the bacterial numbers in the melted ice and thus reduced the potential for cross-contamination.
The antimelanosic and antioxidative properties of a hot water extract prepared from the fruiting body of the edible mushroom (Flammulina velutipes) were evaluated by dietary supplementation in Kuruma shrimp (Marsupenaeus japonicus) for possible aquaculture application. The extract contained ergothioneine (ERT) at a level of 2.05 mg/mL. A commercial standard of l-ergothioneine (l-ERT) and the mushroom extract showed inhibitory activity against mushroom polyphenoloxidase (PPO). Feeding of the extract had no adverse effects on the immune systems of the shrimp under the present experimental conditions. Supplementation of the extract in the diet significantly suppressed PPO activities in the hemolymphs of the shrimp. Expression of the prophenoloxidase (proPO) gene decreased in the hemocyte of the Kuruma shrimp fed with the mushroom extract. Consequently, development of melanosis was significantly suppressed in the supplement fed shrimp during ice storage. Lipid oxidation was also effectively controlled in the supplement fed group throughout the storage period. In vitro experiments showed that l-ERT effectively inhibited the activation of proPO in the hemocyte lysate supernatant (HLS). The transcript of the proPO gene in the hemocyte showed lower expression in the l-ERT-treated HLS. It was concluded that dietary supplementation of the mushroom extract in shrimp could be a promising approach to control post mortem development of melanosis and lipid oxidation in shrimp muscles.
The present study evaluated the combined effect of Modified Atmosphere Packaging (MAP) using two different gas mixtures (40% CO2/50% N2/10% O2; treatment M1, 60% CO2/30% N2/10% O2, treatment M2), and thyme oil (0.2% v/w, T) used as a natural preservative, on the quality and shelf life extension of fresh filleted sea bass, product of organic aquaculture, during refrigerated storage (4 +/- 0.5 degrees C), for a period of 21 days. Aerobically packaged sea bass fillets (A) were used as control samples. The dominant bacteria in the microflora of sea bass fillets, irrespective of treatment, were the pseudomonads and the H2S-producing bacteria while lactic acid bacteria were also part of the dominant microflora. Total viable counts for fresh sea bass fillets stored aerobically exceeded 7 log CFU/g after 7 days, while treatments A+T, M1, M2 and M2+T reached the same value on days 9, 10, 12 and 19, respectively. Among the chemical indices determined, TBA values were within the good quality limits (2-4 mg MDA/kg), during the sensory shelf lives of sea bass samples, irrespective of treatment. TVB-N proved to be a suitable index for the spoilage of sea bass fillets stored at 4 degrees C. Samples A and A+T, M1, M2, M2+T exceeded the proposed upper TVB-N acceptability limit (10 mg N/100 g) on days 6, 8, 9, 13 and 17 of storage respectively. TMA-N values of the samples A, A+T and M1, M2, M2+T exceeded the proposed limit (4 mg N/100 g) on days 6, 9, 9-10, 13 and 19 of storage, respectively, and correlated well with the microbiological data, indicating that along with TVB-N, TMA-N may serve as a useful index for sea bass fillets spoilage. As regards sensory evaluation, the presence of thyme oil proved to improve the sensory quality of sea bass fillets when used in combination with MAP2, providing a shelf life of 17 days as compared to 6 days of the control samples.
The distribution of microorganisms in pozol balls, a fermented maize dough, was investigated by a polyphasic approach in which we used both culture-dependent and culture-independent methods, including microbial enumeration, fermentation product analysis, quantification of microbial taxa with 16S rRNA-targeted oligonucleotide probes, determination of microbial fingerprints by denaturing gradient gel electrophoresis (DGGE), and 16S ribosomal DNA gene sequencing. Our results demonstrate that DGGE fingerprinting and rRNA quantification should allow workers to precisely and rapidly characterize the microbial assemblage in a spontaneous lactic acid fermented food. Lactic acid bacteria (LAB) accounted for 90 to 97% of the total active microflora; no streptococci were isolated, although members of the genus Streptococcus accounted for 25 to 50% of the microflora. Lactobacillus plantarum and Lactobacillus fermentum, together with members of the genera Leuconostoc and Weissella, were the other dominant organisms. The overall activity was more important at the periphery of a ball, where eucaryotes, enterobacteria, and bacterial exopolysacharide producers developed. Our results also showed that the metabolism of heterofermentative LAB was influenced in situ by the distribution of the LAB in the pozol ball, whereas homolactic fermentation was controlled primarily by sugar limitation. We propose that starch is first degraded by amylases from LAB and that the resulting sugars, together with the lactate produced, allow a secondary flora to develop in the presence of oxygen. Our results strongly suggest that cultivation-independent methods should be used to study traditional fermented foods.
Electrolyzed water (EW) is gaining popularity as a sanitizer in the food industries of many countries. By electrolysis, a dilute sodium chloride solution dissociates into acidic electrolyzed water (AEW), which has a pH of 2 to 3, an oxidation-reduction potential of >1,100 mV, and an active chlorine content of 10 to 90 ppm, and basic electrolyzed water (BEW), which has a pH of 10 to 13 and an oxidation-reduction potential of -800 to -900 mV. Vegetative cells of various bacteria in suspension were generally reduced by > 6.0 log CFU/ml when AEW was used. However, AEW is a less effective bactericide on utensils, surfaces, and food products because of factors such as surface type and the presence of organic matter. Reductions of bacteria on surfaces and utensils or vegetables and fruits mainly ranged from about 2.0 to 6.0 or 1.0 to 3.5 orders of magnitude, respectively. Higher reductions were obtained for tomatoes. For chicken carcasses, pork, and fish, reductions ranged from about 0.8 to 3.0, 1.0 to 1.8, and 0.4 to 2.8 orders of magnitude, respectively. Considerable reductions were achieved with AEW on eggs. On some food commodities, treatment with BEW followed by AEW produced higher reductions than did treatment with AEW only. EW technology deserves consideration when discussing industrial sanitization of equipment and decontamination of food products. Nevertheless, decontamination treatments for food products always should be considered part of an integral food safety system. Such treatments cannot replace strict adherence to good manufacturing and hygiene practices.
Protease activity during storage is thought to be an important contributor to decreased shelf life of fresh seafood. To examine this, three batches of red swamp crayfish ( Procambarus clarkii) tails, placed on trays, were packed with a polyvinyl chloride film (aerobic packaging or AP), under vacuum (vacuum packaging or VP), or under a modified atmosphere (MAP: 80% CO 2/10% O 2/10% N 2), and proteolytic activity was measured on days 0, 1, 3, 6, and 10 during storage at 2 degrees C. The crude extract from the crayfish digestive system (gut) did not have an apparent role in muscle proteolysis as negligible proteolytic activity was detected. However, the loss of calpastatin (the endogenous calpain inhibitor) was identified in MAP-stored muscle samples on day 10, suggestive of high m-calpain activity. Tail samples stored in AP showed no appreciable proteolysis, but those stored in MAP and VP showed significant decreases in the levels of 53, 66, 71, and 110 kDa polypeptides during storage. The observed proteolytic activity and myofibrillar protein degradation did not correspond to muscle textural properties as the MAP samples had an increased toughness ( P < 0.05) after storage for 10 days. These findings suggest that other physicochemical mechanisms are involved in postmortem alteration in the crayfish muscle structure under the packaging systems investigated.
A new formula for a half oxidized hematoxylin solution has been developed from modern chemical information. It is composed of low cost, readily available ingredients that are easily soluble and reactive at room temperature; boiling is not required in its preparation. Further, the solution in storage retains its usefulness for about a year. At the rate of about 2,500 slides/wk, this hematoxylin need be changed only monthly, with occasional replenishment. The solvent system prevents the wasteful precipitation of aluminum hematein, the troublesome scum that forms daily in some hematoxylins. In practice, the concentration of its ingredients allows this hematoxylin to act as a progressive stain which limits its own action and eliminates the need for differentiation in acid. As a result, microscopists' requirements for a high contrast, reproducible stain are achieved, whereby nuclei are stained blue to blue black at a desirable density, parachromatin is lightly tinted, nucleoli are superficially stained so that their acidophilia can be displayed, and cytoplasm is negligibly tinted so that the colors of subsequently applied counterstains are not degraded. In stored stained specimens, this hematoxylin exhibits remarkable fastness. Explanations are offered for the role of each ingredient in this hematoxylin formula. As a further demonstration of their usefulness, the explanations have been correlated with the properties and performance of Harris' and Mayer's hematoxylins.
Postmortem tenderization is caused by enzymatic degradation of key structural proteins in myofibrils as well as in extracellular matrix, and of proteins involved in intermyofibrillar linkages and linkages between myofibrils and the sarcolemma. The function of these proteins is to maintain the structural integrity of myofibrils. Current data indicate that calpains and cathepsins may be responsible for degradation of these proteins. Other phenomena occurring in cells postmortem (pH drop, sarcoplasmic Ca2+ increase, osmotic pressure rise, oxidative processes) may act in synergy with proteases. Our understanding of the underlying mechanisms of muscle degradation should be improved for an accurate evaluation of the postmortem muscle changes and consequently of the fish quality.