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Combined effects of thermosonication and slightly acidic electrolyzed water on the microbial quality and shelf life extension of fresh-cut kale during refrigeration storage
... It leads to better quality (flavor, texture, and appearance) than conventional heat treatment [19][20][21]. Furthermore, when used with chemical sanitizer, ultrasonic or thermosonic treatment can improve the penetration of the chemical sanitizer through the cellular membrane, resulting in an increased sanitizing efficiency [22][23][24]. ...
... Subsequently, the wax gourd samples were immediately immersed in a water bath with 0.5%, 1.0%, or 1.5% (w/v) tea polyphenols solution (sample: solution = 1:3) at 15 • C for 5 min. Excess liquid was then naturally drained in a laminar flow cabinet at room temperature for approximately 10 min [23]. ...
... The resulting homogenates were serially diluted in BPW, and 0.1 mL of each dilution was plated onto a range of XLT4 agar, which is a selective medium for Salmonella and displays specific black or black-centered colonies. The plates were incubated at 37 • C, and the colonies were counted and recorded as log CFU/g [23,33,36]. ...
Fresh-cut vegetables are exposed to the risk of Salmonella spp. contamination. Effective sterilization methods and early warning systems play important roles in ensuring food safety of fresh-cut products. The aim of this study was to evaluate the effect of tea polyphenols (TP) combined with thermosonication (TS) treatment on inactivation of Salmonella enterica in fresh-cut wax gourd and to develop and estimate models using adaptive neuro-fuzzy inference system (ANFIS) with different membership functions (MFs) for predicting S. enterica population during storage at 25, 10, and 4 °C, respectively. The results showed that both TP and TS treatment can effectively reduce the population of S. enterica in fresh-cut wax gourd. The combination of TP (1.0%) and TS (50 °C, 1 min) treatment followed by storage at 4 °C may be a suitable bacteriostatic scheme for the preservation of fresh-cut wax gourd. Fluorescence microscopy analyses indicated that TP and TS treatment could lead to the destruction of the cell membrane, followed by the leakage of cytoplasm, and, finally, cell death. ANFIS with the gaussmf function performed well in modeling and predicting the population of Salmonella in fresh-cut wax gourd and provided a powerful tool for modelling and predicting microbe population and the shelf life of food products.
... Mean L. innocua growth in this study is greater than the reported 1.2 log increase over 10 days in kale stored at 7℃ by Lokerse et al. (2016) (Figure 5). Initial values for APC in this study were lower compared to reported initial values for aerobic mesophilic counts in kale by Mansur et al., (2015). Initial values by Mansur et al., (2015) ranged between ~5.5-6.3 log CFU/g, however final populations were similar to APC and PPC concentrations in this study ranging between ~7.3-8.6 log CFU/g. ...
... Initial values for APC in this study were lower compared to reported initial values for aerobic mesophilic counts in kale by Mansur et al., (2015). Initial values by Mansur et al., (2015) ranged between ~5.5-6.3 log CFU/g, however final populations were similar to APC and PPC concentrations in this study ranging between ~7.3-8.6 log CFU/g. Both studies show background microbiota grew similarly and reached the maximum carrying capacity of kale at both 4 and 8℃. ...
... However, at such a high inoculation level L. monocytogenes likely grew to the maximum capacity of chopped kale and growth stopped when populations reached ~8 log CFU/g at both storage temperatures. Total growth values for L. monocytogenes in kale when held at 7℃ using a 3 log CFU/g inoculum can be considered similar to the final increases seen in kale inoculated at 6 log CFU/g when the differing storage times are taken into account (10 and 14 days, respectively)(Lokerse et al., 2016;Mansur & Oh, 2015). Had the low inoculation study been extended through 14 days, another ~0.8 log of growth may have occurred to match the high inoculation study's population increase.Both studies indicate that kale can support the growth of L. monocytogenes and should be further assessed for growth risk. ...
The fresh-cut produce industry has seen expansive growth in recent years, to meet consumer demand ready-to-eat (RTE) salads have included the use of non-traditional ingredients. Uncommon ingredients include beet greens, kale, broccoli stalk, and Brussels sprouts, since these ingredients have not historically been consumed raw, potential food safety issues should be reassessed. Current processing technologies include produce washes that can reduce microbial levels but do not eradicate all populations. The lack of a kill step in produce processing emphasizes the need to minimize pathogen contamination during production and growth during a product’s shelf life. Listeria monocytogenes, a leading cause of foodborne illness related deaths, continues to challenge the industry with recent outbreaks and recalls of fresh-cut produce. These events present the need to better understand L. monocytogenes growth potential in RTE produce during storage and distribution. Traditional salad greens have been researched extensively, however, limited knowledge is available on new inclusions. While temperature is known to strongly influence microbial growth, the effects of physical abuse during storage and distribution are unknown. The purpose of this study was to characterize L. innocua’s, a surrogate for L. monocytogenes, growth behavior in processed beet greens, kale, broccoli stalk, and Brussels sprouts when exposed to simulated physical and thermal abuses during storage and distribution. To evaluate L. innocua growth during storage and distribution produce samples were obtained from a local processor in retail packaging and surface inoculated. The samples were conditioned at 4℃ for 18h prior to being exposed to a series of physical abuses (compression, drop, and vibration) typical of storage and distribution. After abuse, produce was incubated at 4 or 8°C and sampled post-abuse through 16 and 11 days, respectively. Samples were enumerated for L. innocua, aerobic and psychrotrophic microorganisms, and lactic acid bacteria. To monitor growing conditions in each vegetable, product pH, water activity, and headspace (gas analysis), were observed at each time pull. The study found physical abuse had no significant effect on L. innocua, or microbiota growth regardless of vegetable or incubation temperature (P > 0.05). Vegetable intrinsic factors (pH, Aw, and headspace) did not seem to interfere in L. innocua or background microbiota growth during incubation. All vegetables supported L. innocua growth under 8℃. Growth of L. innocua was greatest in beet greens, followed by kale, broccoli stalk, and Brussels sprouts in descending order. Significant growth of L. innocua at 4 and 8ᵒC was seen on day 6 and 4 in beet greens, 11 and 6 in Brussels sprouts, 16 and 4 in kale, and 16 and 6 in broccoli stalk (P < 0.05). Overall, these results show the studied RTE vegetables can support L. monocytogenes growth during storage and distribution, especially under abusive temperatures, demonstrating the importance of prevention strategies during processing and refrigeration throughout RTE produce shelf life.
... Because of its minimal running expenses and excellent antibacterial action [4 it has been frequently used to sterilize goods (e.g., fruits [59], vegetables, and meat). Wh electrolytic water is used, microorganisms (e.g., Escherichia coli, Staphylococcus aureus, S monella, vibrio parahaemolyticus and Bacillus cereus) all exhibit the effects of considera antibacterial activity [60]. SAEW exhibits bactericidal properties by attacking multiple gets of microbial cells (e.g., cell walls, extracellular membranes, and intracellular com nents) [61]. ...
... Because of its minimal running expenses and excellent antibacterial action [46], it has been frequently used to sterilize goods (e.g., fruits [59], vegetables, and meat). When electrolytic water is used, microorganisms (e.g., Escherichia coli, Staphylococcus aureus, Salmonella, vibrio parahaemolyticus and Bacillus cereus) all exhibit the effects of considerable antibacterial activity [60]. SAEW exhibits bactericidal properties by attacking multiple targets of microbial cells (e.g., cell walls, extracellular membranes, and intracellular components) [61]. ...
Ultrasound has been confirmed as the propagation process of mechanical vibrations in a medium, with a frequency significantly higher than 20 kHz. Moreover, it has an effect of sterilization on foods. In general, ultrasonic sterilization medium is manifested as a liquid. Ultrasonic treatment technology has certain advantages in aquatic product processing. It is noteworthy that this technology will have better effects of sterilization if used in combination with other treatment methods. Slightly acidic electrolyzed water (SAEW) is characterized by high-efficiency broad-spectrum sterilization operation, low cost, and environmental protection, among other properties, and has a positive effect on aquatic product sterilization and preservation. Selecting acidic electrolyzed water with a low concentration coupled with low-power ultrasonic waves for combined sterilization exerts a more potent sterilization effect, and acidic electrolyzed water combined with ultrasonic sterilization is expected to be a potentially environment-friendly alternative. In this study, the sterilization mechanisms of ultrasonic and SAEW methods used both individually and as a synergistic treatment, the effect on microbial growth, and the research progress of the application of the combined effect in the sterilization and refrigeration of aquatic products are reviewed. Furthermore, this study looks forward to the future development trend, with a view to its application in aquatic products, while providing a reference for research and application in the field of processing and safety.
... However, in some cases, US treatment alone was found to be no benefit for bactericidal efficiency [14]. Thus, US combined with other sanitizers had been used to enhance the inactivation effect on pathogenic in fruits and vegetables [15][16][17]. ...
... Ding, et al. [25] studied that US enhanced the bactericidal activity of SAEW (ACC = 34.33 mg/L) which resulted in 1.50 and 1.29 log reductions on yeasts and molds for cherry tomatoes and strawberries respectively. The inactivation effect of US + SAEW treatment might be due to thermosensation cavitation activity, which caused high pressure and temperature areas, destroying the bacterial cell wall, thus resulting in better penetration of SAEW [17]. ...
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.
... The behavior of L. monocytogenes has also been observed for other brassicas, such as collard greens, kale, and cabbage (14,24,30,38). Sant'Ana et al. (38) found that L. monocytogenes populations remained unchanged on collard greens and yakisoba (containing cauliflower, carrot, broccoli, cabbage, and chard) and declined on cabbage during refrigerated storage (78C). ...
... In another study, L. monocytogenes grew on the surface of kale during 14 days of storage at 4 and 78C (ca. 2.2 log CFU/g) (30). That growth was greater than the growth observed in the present study on broccoli and cauliflower, highlighting the fact that L. monocytogenes growth on produce commodities, including other brassicas, differs depending on storage conditions and produce type. ...
Understanding a food's ability to support the growth and/or survival of a pathogen throughout the supply chain is essential to minimizing large-scale contamination events. The purpose of this study was to examine the behavior (growth and/or survival) of Listeria monocytogenes on broccoli and cauliflower florets stored at different postharvest temperatures utilized along the supply chain. Broccoli and cauliflower samples were inoculated with L. monocytogenes at approximately 3 log CFU/g and stored at 23 ± 2, 12 ± 2, 4 ± 2, and -18 ± 2°C. Samples were evaluated for L. monocytogenes levels after 0, 0.167 (4 h), 1, 2, 3, and 4 days at 23 ± 2°C; 0, 0.167, 1, 2, 3, 4, 7, 10, and 14 days at 12 ± 2°C; 0, 0.167, 1, 2, 3, 4, 7, 10, 14, 21, and 28 days at 4 ± 2°C; and 0, 1, 7, 28, 56, 84, 112, 140, and 168 days at -18 ± 2°C. L. monocytogenes populations were determined by plating samples onto tryptic soy agar and modified Oxford agar supplemented with nalidixic acid. Broccoli and cauliflower supported the growth of L. monocytogenes at 23, 12, and 4°C, and higher growth rates were observed at higher temperatures. Populations of L. monocytogenes on broccoli and cauliflower samples significantly increased within 1 day at 23°C (by 1.6 and 2.0 log CFU/g, respectively) (P ≤ 0.05). At 12°C, populations of L. monocytogenes on broccoli and cauliflower samples significantly increased over 14 days by 1.4 and 1.9 log CFU/g, respectively (P ≤ 0.05). No significant difference over time was observed in L. monocytogenes populations on broccoli and cauliflower samples held under refrigeration until populations began to grow by day 10 in both commodities (P > 0.05). Under frozen storage (-18°C), populations of L. monocytogenes survived on broccoli and cauliflower at least up to 168 days. Storage of broccoli and cauliflower at lower temperatures can minimize L. monocytogenes growth potential; growth rates were lower at 4°C than at 12 and 23°C.
Highlights:
... Similarly, our study revealed a comparable behavior of L. monocytogenes in alfalfa sprouts. Our findings align with previous research where L. monocytogenes demonstrated growth at 4°C in cabbage after 120 h of storage (Wang et al. 2013) and in kale after 100 h of storage (Mansur and Oh 2015). The ability of S. enterica or L. monocytogenes to survive in cold environments is likely attributed to their cell membrane composition and gene expression regulation (Nikparvar et al. 2021). ...
Sprouts are popular due to their high nutritional content, including vitamins, minerals, antioxidants, and enzymes. However, the conditions favorable for sprouting, such as warm and humid environments, are also ideal for the growth of bacteria, including food-borne pathogens. Here, we analyzed the growth and developed predictive models of locally isolated and commercial strains of Salmonella enterica and Listeria monocytogenes in alfalfa sprouts under various constant temperatures, ranging from 5°C to 25°C. Our findings indicated that these pathogens could grow at 5°C in sprouts, albeit with a low growth rate. A rapid increase in concentration occurred at temperatures of 10°C and above. The fitted models demonstrated high performance, with R 2 values ranging from 0.964 to 0.997 and RMSE values ranging from 0.15 to 0.51, respectively. Based on the fitted values, bias factor (A f) values varied between 1.01 and 1.06, with all accuracy factor (B f) values at 1.00. Acceptable prediction zone (APZ) values ranged from 81.8% to 100%. Validation of the models under dynamic temperature conditions for specific strains showed acceptable performance. This study enhances our understanding of S. enterica and L. monocytogenes growth in alfalfa sprouts. The findings of this study could be used to improve the risk assessment of these pathogens in alfalfa sprouts.
... Furthermore, the consumers are concerned about the use of these chemicals because they may potentially provide undesirable effects on human health. Therefore, most studies on the decontamination of fresh meat or vegetables have focused on sanitizing agent alternative to chlorine [9,10]. Electrolyzed water with a pH of 5.0-6.5 is well recognized as an alternative sanitizer, containing a high concentration of hypochlorous acid [11]. ...
During beef processing, contamination by microorganisms from diverse sources poses a significant risk to its quality and safety.
This contamination can lead to reduced shelf life, compromised meat quality, and increased health hazards. In recent years,
electrolyzed water (EW) has emerged as a promising solution for sanitizing and cleaning beef. The purpose of this study was
to evaluate the physicochemical and sensory qualities of beef that had been treated with EW. In this experiment, there were
three replications with a factorial Randomized Complete Block Design (RCBD). Factor-A: consisted of six (06) treatments
concentrations: T0 = Control sample (fresh water); T1 = 10 ppm electrolyzed water; T2 = 20 ppm electrolyzed water; T3 = 30 ppm
electrolyzed water; T4 = 40 ppm electrolyzed water; T5 = 50ppm electrolyzed water; Factor-B: consisted of three (03) durations:
TM1 = 5 minutes; TM2 = 10 minutes; TM3 = 15 minutes. The findings showed that the moisture content (%), crude protein (%),
ether extract (%) and ash content (%) of beef samples ranged from 72.31 ± 0.29 to 73.93 ± 0.30, 19.95 ± 0.16 to 21.91 ± 0.19,
4.28 ± 0.09 to 5.06 ± 0.09, 1.29 ± 0.09 to 1.76 ± 0.07 respectively. Beef's proximate composition (moisture, crude protein, ether
extract, dry matter, and ash) and physical analyses (cooking yield, cooking loss, and pH) were not significantly affected by the
EW treatments (p>0.05). However, drip loss and beef color showed substantial significant effects (p<0.05). Findings suggest
that EW treatments with concentration up to 50 ppm can effectively decontaminate beef while maintaining its nutritional and
sensory properties.
... The cavitation generated by US causes the microbial cell wall in solution to thin, and higher liquid shear forces and shock waves put pressure on the cell membrane [15]. US has been found ineffective in inactivation of L. monocytogenes [16], but can be combined with other antibacterial agents to enhance the bactericidal effect [17]. This study mainly explored the combined antibacterial effect of US and CT, it complements the shortcomings of single treatment, improving the antibacterial efficiency of CT, and reducing US energy consumption, effectively bactericidal at low power. ...
This study investigated the antibacterial effects of ultrasound (US), β-citronellol (CT), and a combination of the two treatments on Listeria monocytogenes. Results showed that US or CT alone did not show apparent antibacterial effect (0.02–0.76 log CFU/mL reduction). The combined treatment showed obviously inactivate effect of L. monocytogenes, the populations of L. monocytogenes decreased by 8.93 log CFU/mL after US (253 W/cm², 20 kHz) + 0.8 mg/mL CT treatment. US + CT treatment also had a significant (P < 0.05) antibacterial effect on isolates of L. monocytogenes from three different serotypes. In this study, the damage of US + CT on cell morphology had been observed using field emission scanning electron microscopy, while the damage to cell membranes by US + CT was observed by confocal laser scanning microscopy and flow cytometry. Meanwhile, the uptake of N-phenyl-l-naphthylamine and the absorbance at 260 and 280 nm also indicated that the combined treatment disrupted the permeability and integrity of L. monocytogenes membranes. Reactive oxygen species and malondialdehyde assays showed that US + CT exacerbated cellular oxidative stress and lipid peroxidation. In addition, the US + CT treatment reduced L. monocytogenes by 3.14–4.24 log CFU/g on the surface of carrots. Total phenolic and carotenoid contents in carrots were elevated after US + CT treatment. During storage, compared to control, US + CT did not significantly (P > 0.05) change the surface color of carrots but significantly (P < 0.05) decreased both hardness and weight, and has an impact on the sensory. This study showed that US + CT is a promising cleaning method that will provide new ideas for the preservation of fresh agricultural produce.
... During the process, while FAC is generated at the anode of the membrane electrolyser, a low pH and a high oxidation-reduction potential (ORP), both are factors commonly recognised to possess sanitising power, are generated simultaneously (He et al., 2021). So far, many studies have confirmed the effectiveness of AEW in mitigating microbial loads on fresh produce (Ke, 2015;Mansur & Oh, 2015;Sow et al., 2017;Tango et al., 2017;Wang, Wu, & Yang, 2022;Zhao et al., 2019). Yet, no direct in-food comparison has been made between the sanitising effects of AEW and NaClO on "big six". ...
Sodium chlorite (NaClO), the most commonly used sanitiser for fresh produce decontamination, is associated with the problems of pungency and corrosiveness. In search for a more environmentally- and user-friendly chlorine-based sanitiser, acidic electrolysed water (AEW), came into view in recent years. To determine whether AEW is an ideal alternative to NaClO, using ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS), this study thoroughly investigated the effectiveness of AEW and NaClO, both containing 4 mg/L of free available chlorine (FAC), in inhibiting the “big six” Escherichia coli pathogens (serotypes O26, O45, O103, O111, O121 and O145) on lettuce as well as the underlying antimicrobial mechanisms. The two sanitisers led to generally comparable E. coli cell reductions after a 10-min treatment, which indicated the decisive role of FAC in their antimicrobial effects. Among the strains, mortalities varied from approximately 0.68 log CFU/g in O111 under both treatments to 1.48 ± 0.04 log CFU/g in AEW-treated O26 and 1.23 ± 0.04
log CFU/g in NaClO-treated O45. O111’s high resistance was confirmed by its almost undisturbed metabolome whereas the high lethality of O26 and O45 could be attributed to the loss of membrane phospholipids. Besides, retarded cell growth and energy deficiency as implied by a vast depletion of nucleotide derivatives further challenged O45’s survival. Overall, the comparable sanitising efficacy and the similarity in antimicrobial
mechanisms between the two sanitisers provided a scientific basis for replacing NaClO with the “greener” AEW for fresh produce sanitisation in the future.
... Zhang et al., 2021). SAEW is effective against spoilage and pathogenic microorganisms like Pseudomonas spp., Enterobacteriaciae, E. coli, Salmonella spp, L. monocytogenes (Forghani and Oh, 2013;Issa-Zacharia et al., 2011;Mansur & Oh, 2015). Tap water and table salt (NaCl) are the only two chemicals needed to generate SAEW in non-membrane electrolytic cell (Ahmed et al., 2022). ...
Slightly acidic electrolyzed water (SAEW) has recently gained a lot of interest as a chlorine sanitizer which provides higher decontamination effect with minimum available chlorine. Nevertheless, microbial reductions via only SAEW treatment are not sufficient to assure safety. Hence, it is required to enhance the disinfection efficacy by combining with other compatible techniques. In the present study, SAEW with a pH of 5.5-5.6, available chlorine content (AAC) of 20-22 mg/L, oxidation-reduction potential of 900-950 mV was applied on fresh-cut cauliflower to determine the microbicidal activity. SAEW was also applied in combination with ultrasound treatment (US) and moderate heat (45 • C) to enhance the decontamination efficacy of SAEW. The impacts of individual (SAEW) and combined treatments like (SAEW + US), (SAEW + US + mild heat 45 • C) on microbial population, physicochemical, and antioxidant properties of cauliflower were evaluated. The combined treatment of SAEW, US and mild heat showed better effectiveness on microbial decontamination compared to SAEW treatment alone, and SAEW with US (SAEW + US) treatment but significantly reduced the antioxidant and phytochemical properties of fresh cauliflower. However, SAEW with US treatment (SAEW + US) preserved the bioactive compounds and antioxidant activity with significant reduction of microbial load. The present study revealed that combination of SAEW with US treatment can be a promising decontamination technique to improve postharvest quality and safety of fresh produce.
... As confirmed in the present study, the growth of L. monocytogenes is dependent on plant species. These different rates of growth or even the lack of growth have been well reported in the literature, where experimental and pre-harvest conditions varied considerably between the reported studies putatively affecting the outcomes [18,19,[21][22][23]37,38]. Similarly, albeit at high inoculation levels, growth and survival of a gfp marked E. coli O157:H7 strain appeared to be highly dependent on the plant species, i.e., baby leaf spinach, rocket, and Swiss chard [39]. ...
Leafy vegetables are associated with Listeriosis outbreaks due to contamination with Listeria monocytogenes. To date, contradictory findings were reported on spinach, rocket, and kale, where some studies reported growth of L. monocytogenes, while others did not. Thus, the current study investigated the reason for conflicting findings by producing leafy vegetables, where cultivation factors were known for growth potential studies. Of all polytunnel produce, kale Nero di Toscana demonstrated the highest growth potential (2.56 log cfu g−1), followed by spinach F1 Cello (1.84 log cfu g−1), rocket Buzz (1.41 log cfu g−1), spinach F1 Trumpet (1.37 log cfu g−1), and finally rocket Esmee (1.23 log cfu g−1). Thus, plant species and variety influenced L. monocytogenes growth potentials. Moreover, significantly lower growth potentials of 0.3 log cfu g−1 were identified when rocket Buzz was cultivated in open fields (1.11 log cfu g−1) instead of a polytunnel. The opposite effect was observed for spinach F1 Trumpet, where growth potentials increased significantly by 0.84 log cfu g−1 when cultivated in open fields (2.21 log cfu g−1). Furthermore, a significant seasonality effect between batches was found (p < 0.05). This study revealed that spinach and rocket cultivation conditions are at least co-factors in the reporting of differing growth potentials of L. monocytogenes across literature and should be considered when conducting future growth potential studies.
... EW was also tested as a disinfectant for equipment such as kitchen boards, glass, stainless steel, enameled and unglazed ceramics, and industry vitreous porcelain, showing bacterial reductions between 2 and 6 log/CFU (Huang et al., 2008). Other studies on bacteria inactivation report a reduction, on average, from 1 (Koseki, Yoshida, Isobe, & Itoh, 2004;Ayebah, Hung, & Frank, 2005;Park, Hung, Lin, & Brackett, 2005;Mansur & Oh;Ogunniyi et al., 2021a;Ogunniyi et al., 2021b) to about 6 log CFU (Ovissipour et al., 2018). No similar studies evaluating antifungal action were found. ...
Controlling food spoilage fungi remains a challenge for food industries, and regulations on the usage of chemical disinfectants are becoming restrictive. Then, this study aimed to evaluate electrolyzed water (EW) as a sustainable alternative for food spoilage fungi inactivation. The experiment was carried out according to the protocol for testing the antifungal effects of chemical sanitizers by the European Committee for Standardization (CEN), using acidic electrolyzed water (AEW-AAC: 85 ppm; pH: 2.65; ORP: 1120 mV) and a basic electrolyzed water (BEW- pH: 11.12; ORP: -209 mV) to inactivate spoilage fungi strains from bread (Hyphopichia burtonii and Penicillium roqueforti) and cheese (P. roqueforti and Penicillium commune), besides the standard fungi for this type of essay (Candida albicans and Aspergillus brasiliensis). AEW presented a higher antifungal effect, inactivating an average of 89% of the exposed population when compared to its respective BEW, which inactivates about 81.5%. In general, the standard strains A. brasiliensis (ATCC 16404) and Candida albicans (ATCC 24433) were more sensitive to both AEW and BEW than the food-spoilage strains. Among those, P. roqueforti strains were the most sensitive, followed by P. commune strains, while H. burtonii strains were the most tolerant. EW can be a sustainable alternative for product surface and facility cleaning with further antifungal action when a sanitization step is not mandatory or needed. Future studies searching for conditions to improve the antifungal action of EW could make their industrial usage more viable.
... acephala) is popular worldwide due to its nutritional content and was ranked as 15th from 41 kinds of selected fruits and vegetables foods most strongly associated with reduced chronic disease risk by the Centers for Disease Control and Prevention (CDC; USA) in 2014 (Di Noia, 2014;Satheesh et al., 2020). However, in order to retain its desired attributes, the product is generally minimally processed, and consequently is prone to browning, decreased hardness and other quality changes, resulting in a decline in commercial value, the loss of nutrients and conditions advantageous for the rapid reproduction of microorganisms (such as aerobic bacteria, Pseudomonas spp., aerobic Enterobacteriaceae, yeasts and molds; Zhang and Ye, 2010;Mansur and Oh, 2015;Carstens et al., 2019). Pathogenic microorganisms pose a potential health hazard, because processed kale products are usually eaten raw (Francis et al., 2001). ...
The aim of this study was to examine the effectiveness of plasma activated water (PAW) for inactivating Escherichia coli and retention of key quality factors for kale. Different plasma discharge times (1, 2, 3, 4, 5 and 10 minutes) and different exposure times (2, 4, 6, 8, 10 and 15 minutes) were used to investigate the inactivation effect of E. coli spot-inoculated on kale. The influence of different exposure times on the pH, hardness and color of kale was studied post- treatment. In addition, the effects of PAW on the shelf-life of kale over 12 days of storage at 4 °C was investigated. The results showed that after the treatment of 5-PAW-8 (8 min treatment by PAW generated by 5 min plasma discharge), the population of E. coli on kale was reduced about 1.55 log CFU/g and the changes of pH, hardness and color of kale were not significant (P > 0.05). During the storage period after 5-PAW-8 treatment, the statue of hardness, weight loss, color, surface morphology and ascorbic acid were found to be better than two control groups (P < 0.05). Furthermore, no significant changes were observed in pH values, the content of total phenols and 1,1-dipheny1-2-picrylhydrazyl radical-scavenging capacity (P > 0.05). It is indicated that PAW treatment is a promising method for improving the microbiological safety and extending the shelf-life of kale.
... Human production and life are inseparable from water. Without water, everything does not exist [1][2][3][4] . Although the earth is a blue planet, and the ocean occupies about 70% of the total area, the available freshwater resources are very scarce, accounting for only 2.53% of the total water volume, and 98% of them are glaciers and deep groundwater which distribute at the poles, so that it is difficult to be exploited in areas and buried underground. ...
With the explosive growth of the world’s population and the rapid increase in industrial water consumption, the world’s water supply has fallen into crisis. The shortage of fresh water resources has become a global problem, especially in arid regions. In nature, many organisms can collect water from foggy water under harsh conditions, which provides us with inspiration for the development of new functional fog harvesting materials. A large number of bionic special wettable synthetic surfaces are synthesized for water mist collection. In this review, we introduce some water collection phenomena in nature, outline the basic theories of biological water harvesting, and summarize six mechanisms of biological water collection: increased surface wettability, increased water transmission area, long-distance water delivery, water accumulation and storage, condensation promotion, and gravity-driven. Then, the water collection mechanisms of three typical organisms and their synthesis are discussed. And their function, water collection efficiency, new developments in their biomimetic materials are narrated, which are cactus, spider and desert beetles. The study of multiple bionics was inspired by the discovery of Nepenthes’ moist and smooth peristome. The excellent characteristics of a variety of biological water collection structures, combined with each other, are far superior to other single synthetic surfaces. Furthermore, the main problems in the preparation and application of biomimetic fog harvesting materials and the future development trend of materials fog harvesting are prospected.
... There are many companies that are now trying to design an electrolyzed water generator that can be used for both research purposes and commercialized for general consumption. For example, companies such as Envirolite® [79], RVD Corporation [80], Hoshizaki Electric Co. Ltd [40], EcoLogic Solutions Inc. [81], and Viking pure™ are making electrolyzed water generators which are being used in the research laboratories and commercialization for household usage is being encouraged by these companies. The most common problem in the usage of electrolyzed water in the household is the production of harmful and toxic byproducts. ...
Electrolyzed oxidizing water (EOW) is one of the promising novel antimicrobial agents that have recently been proposed as the alternative to conventional decontamination methods such as heat and chemical sanitizers. Acidic EOW with pH ranging from 2 to 5 is regarded most applicable in the antimicrobial treatment of vegetables and meats. Neutral and alkaline electrolyzed water have also been explored in few studies for their applications in the food industry. Neutral electrolyzed water is proposed to solve the problems related to the storage and corrosion effect of acidic EOW. Recently, the research focus has been shifted toward the application of slightly acidic EOW as more effective with some supplemental physical and chemical treatment methods such as ultrasound and UV radiations. The different applications of electrolyzed water range from drinking water and wastewater to food, utensil, and hard surfaces. The recent studies also conclude that electrolyzed water is more effective in suspensions as compared with the food surfaces where longer retention times are required. The commercialization of EOW instruments is not adopted frequently in many countries due to the potential corrosion problems associated with acidic electrolyzed water. This review article summarizes the EOW types and possible mechanism of action as well as highlights the most recent research studies in the field of antimicrobial applications and cleaning. Electrolyzed water can replace conventional chemical decontamination methods in the industry and household. However, more research is needed to know its actual mechanism of antimicrobial action along with the primary concerns related to EOW in the processing of different food products.
... The addition of mild heat to US treatment have also been explored, where a more pronounced effect of US (35 kHz, 120 W, and 21.4 W/L) was reported at 65 • C on red bell pepper, watercress, and strawberry, with improved quality retention and enhanced reductions of 7.43, 8.24, and 8.10 log CFU/g for L. innocua, total mesophiles, and total coliforms, respectively [56]. Similarly, the efficacy of US at 40 kHz, 400 W/L combined with SAEW was also enhanced at 40 and 60 • C, respectively, for fresh cut kale and bell pepper [21,86,87]. Browning and off-odor were under acceptable limits for fresh cut kale, while hardness and color parameters for control and treated samples were not significantly different for bell pepper. ...
Ultraviolet-C radiation and ultrasound technology are widely accepted and continuously being appraised as alternatives to conventional thermal techniques for decontamination of fruits and vegetables. However, studies in these areas have presented challenges related to quality, safety, limited capability, and cost of energy. This review paper presents an up-to-date summary of applications of ultraviolet-C radiation and ultrasound technology for postharvest handling of fruits and vegetables from relevant literature. The limitations associated with applications of ultraviolet-C radiation and ultrasound technology individually has prompted their combination alongside other antimicrobial strategies for enhanced bactericidal effect. The combination of ultraviolet-C radiation and ultrasound technology as a hurdle approach also provides enhanced efficiency, cost effectiveness, and reduced processing time without compromising quality. The review includes further scope of industrial-led collaboration and commercialization of ultraviolet-C radiation and ultrasound technology such as scale-up studies and process optimization.
... Mansur et al. [42] evaluated the use of AEW and slightly AEW (SAEW) (pH 6.29) on 10 g of fresh pork loins. As a novelty, they evaluated the combination of SAEW with 0.5% fumaric acid (FA). ...
Food demand is increasing every year and, usually animal-derived products are generated far from consumer-places. New technologies are being developed to preserve quality characteristics during processing and transportation. One of them is electrolyzed water (EW) that helps to avoid or decrease the development of foodborne pathogens, or losses by related bacteria. Initially, EW was used in ready-to-eat foods such as spinach, lettuce, strawberries, among others; however, its application in other products is under study. Every product has unique characteristics that require an optimized application of EW. Different sanitizers have been developed; unfortunately, they could have undesirable effects like deterioration of quality or alterations in sensory properties. Therefore, EW is gaining popularity in the food industry due to its characteristics: easy application and storage, no corrosion of work surfaces, absence of mucosal membrane irritation in workers handling food, and it is considered environmentally friendly. This review highlights the advantages of using EW in animal products like chicken, pork, beef, eggs and fish to preserve their safety and quality.
... Sengül, Erkaya, Baslar, and Ertugay (2011) reported that the ultrasound has an effect on microbial decontamination by combining with other technologies (high pressure, UV, temperature, electrolyzed water, etc.). Mansur and Oh (2015) studied with the fresh-cut kale during storage which was inoculated with Listeria monocytogenes. In that study, they applied thermosonication and slightly acidic electrolyzed water to the samples at different concentrations and the most effective method was detected as thermosonication with electrolyzed water (5 mg/L). ...
In this study, we aimed to use ultrasound and low-intensity electrical current practices to make lettuce safer for human health. For this purpose, three electric currents (0.2, 0.8, and 1.4 mA) and two ultrasonic processes (24 and 40 kHz), used both separately and simultaneously, were applied to the lettuce leaves at five treatment time (2–10 min). At the first stage, the effects of these processes on the microbiota of the fresh lettuce leaves were investigated. Therefore, the TMAB, the total coliform, the total yeast&mold were determined as 5.94 ± 0.20, 5.65 ± 0.27, and 4.82 ± 0.33 log cfu/g, respectively. After the processes, the maximum inactivation rates were determined as 2.89log, > 3log, and 2.98log, respectively. While there was no dramatic change in physicochemical properties of lettuce; the free chlorine and hydrogen peroxide contents increased with the time in the process water. At the second stage, the effects of these processes on pathogens were investigated. 6 log of E.coli O157:H7, L.monocytogenes and, S.aureus were inoculated to the lettuce samples and was treated by the processes. The pathogenic microorganisms in the lettuce samples were inactivated up to 4.05, 3.12, and 2.84 log cfu/g, respectively. In the model system, the pathogens couldn't be detected after 6, 8 and 4 min, respectively.
... It is also environmentally friendly and highly safe (Chemat et al. 2011). Mansur and Oh (2015) evaluated the efficacy of thermosonication (TS) in combination with slightly acidic electrolyzed water (SAcEW) to extend the shelf life of freshcut kale during the refrigerated storage. The vegetable was inoculated with Listeria monocytogenes and treated with TS + SAcEW. ...
Feasible use of ultrasonic treatment (UT) in combination with modified atmosphere packaging (MAP) to preserve pakchoi was evaluated. Pakchoi was treated with ultrasound (30 kHz) for different periods of time (5 min, 10 min, and 15 min) prior to MAP (with 5% O2 + 10% CO2 + 85% N2); the treated vegetables were then stored at 4 °C for 30 days. UT in combination with MAP could retard an increase in the total number of colonies in pakchoi during the storage. UT-10 min decreased the initial total number of colonies in pakchoi from 7.11 to 6.01 log CFU/g and effectively slowed down the increase in mass loss, yellowing, cell membrane permeability, and malondialdehyde content of the stored vegetable; such a treatment also slowed down the decrease in total soluble solids and losses of ascorbic acid and chlorophylls. The synergistic effect of UT and MAP results in effective reduction of peroxidase and polyphenol oxidase activities. In conclusion, UT-10 min + MAP was the best method to preserve pakchoi for 30 days.
... Our findings indicated that SAEW has high bactericidal activity against S. Enteritidis and E. coli for shelled eggs, and it may be an alternative disinfectant for shelled eggs. Moreover, previous work has demonstrated that the application of SAEW in food products could not only reduce the initial microbial load but also extend the shelf life of the food products (Rahman et al., 2013;Mansur and Oh, 2015;Sheng et al., 2018). Duan et al. (2017) evaluated the effects of various disinfectant sprays on initial microbial load and conducted a shelf-life study of chilled chicken carcasses, and they found that SAEW spray was the most effective treatment with reductions of 0.47 to 0.83 log 10 CFU/cm 2 and 0.49 to 0.96 log 10 MPN/cm 2 in total viable counts and total coliforms, respectively. ...
This study evaluated the efficacy of slightly acidic electrolyzed water (SAEW) for the inactivation of Salmonella Enteritidis and Escherichia coli on shelled eggs as well as studied the shelf life and internal quality attributes (i.e., weight loss, Haugh unit, yolk index, albumen pH, and yolk pH) of eggs during storage at 25°C. The decontamination test egg samples (freshly laid) were inoculated and immersed for 1, 2, 3, and 4 min in each treatment (i.e., SAEW, acidic electrolyzed water, NaClO solution, and sterile deionized water) at available chlorine concentrations (ACCs) of 10, 18 and 26 mg/L. The storage test eggs (freshly laid) were immersed for 3 min in 4 treatments (i.e., SAEW, acidic electrolyzed water, NaClO solution, and no treatment) and stored for 30 D at 25°C. The effects of the SAEW on microbiological qualities and freshness parameters were investigated. Decontamination of eggs with SAEW showed an equivalent or higher bactericidal effect compared to other treatments. A complete inactivation of S. Enteritidis and E. coli on the surface of shelled egg samples resulted from treatment with SAEW at an ACC of 26 mg/L for 3 and 4 min, respectively. Almost all of the egg quality parameters investigated in the present study were significantly (P < 0.05) affected by the storage time. As storage time increased, the yolk index and Haugh unit value decreased, and weight loss, albumen pH, and yolk pH increased. However, SAEW treatment minimized weight loss (5.52%) and preserved the albumen and yolk quality better than no treatment at 25°C. Relative to acidic electrolyzed water and NaClO solution, the advantages of SAEW are reduced corrosion of egg surfaces and potentially less water and CO2 escaping from eggshell pores. The results highlight the promising use of SAEW to enhance the microbial safety and to extend the shelf life of shelled eggs. Future combined methods with SAEW and other treatments are also needed.
... Microbial loads were shown to be significantly different on fresh fruits and vegetables, depending on the type of fresh produce and the growing condition. Mostly, TAB counts are useful for indicating the shelf life duration and microbial quality of food (Mansur and Oh, 2015). Ragaert et al. (2007) reported that microbial counts at levels of [ 7.00 log 10 CFU/g are involved in deteriorating organoleptic changes of minimally processed products, thereby resulting in consumer rejection. ...
Contamination of fresh vegetables and berries with human enteric viruses is a major cause of food poisoning. The aim of this study was to investigate the prevalence of norovirus GI, norovirus GII, hepatitis A virus (HAV), adenovirus, astrovirus, rotavirus, and male-specific coliphage systematically in fresh fruit and vegetables and associated agricultural environmental samples, including irrigation water, soil, and worker's gloves. Enteric viruses were detected by international standard methods (ISO/TS 15216), and male-specific coliphages were isolated using US EPA Method 1601. For the study, 773 samples were collected from June 2016 to April 2017, including Chinese cabbage (n = 244), cucumber (n = 98), lettuce (n = 73), strawberry (n = 120), soil (n = 191), irrigation water (n = 14), and gloves (n = 27). Two cucumber and two irrigation water samples were positive for norovirus GI, and one cucumber and two irrigation water samples were positive for norovirus GII. HAV was detected in one strawberry sample and one glove sample. The other tested foodborne viruses were not detected in any of the samples. Sixteen male-specific coliphages were isolated from Chinese cabbage, cucumber, lettuce, cherry tomato, soil, and irrigation water. The isolation of male-specific coliphage would be more practical to investigate the fecal contamination in produce rather than pathogenic viruses.
... The application of thermosonication was also reported in reducing Bacillus cereus spores in rice porridge, beef slurry and cheese slurry by 7-folds, 6-folds and 4-folds, respectively (Evelyn and Silva, 2015). Various researchers have implied that thermosonication has a positive effect on the destruction of Escherichia coli, Penicillium digitatum, Salmonella sp. and Listeria monocytogenes without changing the product quality (Sams and Feria, 1991;Manas et al., 2000;Lopez-Malo et al., 2001;Lee et al., 2009;Mansour and Oh, 2015). Moreover, some studies have reported effective inhibition in meat and meat products such as beef and pork (McDonnell et al., 2014), Italian salami (Alves et al., 2018) and sausage (Cichoski et al., 2015). ...
Thermosonication and microwave techniques were applied as post pasteurization methods for sausage samples. The pasteurization was performed both in an ultrasonic bath at 80°C for 20, 30 and 40 min and microwave at power levels of 400, 600 and 800W for 15 and 30s and compared with conventional pasteurization (75°C, 15 min) and the control (without pasteurization). The results showed that thermosonication and microwaves effectively inhibited microbial growth during storage. However, these techniques significantly affected hardness, springiness, cohesiveness and chewiness (p ≤ 0.05) of the treated sausages. When considering the sensory characteristics of the treated samples, there were no significantly different from that the conventional pasteurization samples (p > 0.05). Thermosonication at 80°C for 20 min was the optimal condition that able to maintain the quality and extend the shelf life, while microwave heating with the power level at 400W for 30s was also inhibited the similar result. Hence, thermosonication and microwave heating have potential for applying in sausage production process to extend the shelf life of sausage products and to maintain overall quality with greater energy efficiency.
... Furthermore, the consumers are concerned about the use of these chemicals because they might have potentially undesirable effects on human health. Therefore, most studies on the decontamination of fresh meat or vegetables have focused on alternative sanitizing agents to chlorine (Gil, Selma, Lopez-Galvez, & Allende, 2009;Guentzel, Lam, Callan, Emmons, & Dunham, 2008;Mansur & Oh, 2015). ...
Studies on slightly acidic electrolyzed water (SAEW) for decontamination and shelf life extension of beef are limited. This study aimed to evaluate the effects of SAEW and tea polyphenols (Tpp) on the microbiological, physicochemical, and sensory qualities of fresh beef during storage. The changes in total viable count, thiobarbituric acid content, pH, total volatile basic nitrogen, and sensory scores revealed that the required quality standard of the beef treated with distilled water, Tpp, and SAEW was maintained for up to 6–8, 12–14, and 14–16 days, respectively. These results demonstrated that SAEW could effectively extend the shelf life of beef in comparison with that of other treatments. However, there were no significant differences (p > 0.05) between the untreated and SAEW‐treated group in the content of thiobarbituric acid, suggesting that SAEW does not possess antioxidant activity. Therefore, further studies are required to increase its antioxidant activity. This study suggests that SAEW treatment is an effective and promising method to prolong the shelf life of beef by around 8 days at 4°C. Our study found that SAEW could effectively extend the shelf life of beef in comparison with that of other treatments. However, there were no significant differences (p > 0.05) between the untreated and SAEW‐treated groups in the content of thiobarbituric acid, suggesting that SAEW does not possess antioxidant activity, and further studies are required to increase its antioxidant activity.
Perishable foods are characterized by a short shelf life, which is an important challenge for the companies that commercialize them. For this reason, the food industry keeps searching for new technologies to preserve their freshness, such as electrolyzed water. This review focuses on near-neutral electrolyzed water (NNEW) with a pH of 5.0–7.5, which has no negative impact on organoleptic characteristics nor on the nutritional quality of foods. It also examines how NNEW can be used to preserve fresh and minimally processed foods, detailing the extension of shelf life after treatments, its effects on food quality (e.g., appearance, texture, and color), and its potential mechanisms for controlling autolytic activity and spoilage microorganisms. Evidence of the attributes of NNEW as a food preservative, besides its well-known sanitizing properties, to extend the shelf life of fresh and MP edible plants and animal products is offered. The review further highlights practical applications for different types of food, including meat, seafood, fruits, and vegetables, and explores how NNEW could be integrated into handling, packaging, and distribution processes. Lastly, the need for large-scale industrial studies is emphasized to determine the feasibility of implementing the use of NNEW to reduce losses in food production and processing facilities, food supply chains, and retail.
Considering the high perishable nature of muscle foods (fish, poultry and red meat) and wide diversity in spoilage microorganisms responsible for spoilage, the prevalence of pathogenic microorganisms in muscle food spoilage is significant. There has been extensive coverage on the emergence of antibiotic resistance in food spoilage microbes in recent years. Chemical preservatives have been extensively employed for the preservation of muscle foods although they have been found to cause toxicity and are not environmentally sustainable. Nevertheless, the scientific community has shown a growing interest in recent breakthroughs in the utilization of innovative clean-label technologies for the preservation of muscle meals, owing to their sustainable characteristics. Among them pulsed light, electrolysed water and ozonation have been under wide exploration. The evaluated sustainable technologies have been found to effectively inhibit the microbial spoilage and reduce the development of antimicrobial resistance. This review discusses potentiality of sustainable technologies in preserving muscle foods with minimal deteriorative impact.
The foodborne pathogen Listeria monocytogenes generally infects immunocompromised individuals, such as cancer patients, more frequently and with higher morbidity and mortality than the general population. Because of the anticipated risk associated with L. monocytogenes and other pathogens in produce, immunocompromised individuals are often placed on neutropenic diets that exclude fresh produce, though these risks have not been quantified. Therefore, this study developed a data-driven risk model for listeriosis in cancer patients who consume ready-to-eat (RTE) salads, consisting of leafy greens, cucumbers, and tomatoes, as influenced by kitchen-scale treatments and storage practices. Monte Carlo simulations were used to model the risk of invasive listeriosis during one chemotherapy cycle. Refrigerating all salad components decreased median risk by approximately one-half log. For refrigerated salads with no treatment, the predicted median risk was ≤ 4.3 × 10-08. When salad ingredients were surface blanched with greens rinsed, the predicted risk decreased to 5.4 × 10-10. Predicted risk was lowest (1.4 × 10-13) for a blanched "salad" consisting of solely cucumbers and tomatoes. Interestingly, rinsing, as recommended by FDA only decreased median risk by 1 log. A sensitivity analysis revealed that the highly variable dose-response parameter k strongly influenced risk, indicating that reducing uncertainty in this variable may improve model accuracy. Overall, this study demonstrates that kitchen-scale pathogen reduction approaches have high risk-reduction efficacy and could be considered as an alternative to diets that exclude produce when making risk management decisions.
Campylobacter and pathogenic Escherichia coli illnesses have been attributed to consumption of fresh produce. The leafy green, kale, is increasingly consumed raw. In comparison to other leafy greens, kale has a longer shelf life. Due to the extended shelf life of kale, it is warranted to examine the survival of pathogenic Campylobacter jejuni and E. coli O157:H7 inoculated on the surface of kale stored in a controlled environment at 4 ± 1.4 °C, and average humidity of 95 ± 1.9% over a 23-day period. At pre-determined time points (days 0, 1, 2, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21), inoculated kale was destructively sampled and the surviving bacteria determined by serial dilution and plating onto Tryptic soy agar, Charcoal cefoperozone deoxycholate agar, and Eosin methylene blue for total aerobic bacteria, C. jejuni and E. coli O157:H7, respectively. Enrichment and PCR were used for detection when pathogens were not detected using serial dilution and plating. Aerobic heterotrophic bacteria increased over the 23-day period, in contrast, significant declines in the inoculated pathogens were observed. Inoculated E. coli O157:H7 survived longer on kale (up to 19 d), in comparison, C. jejuni was undetectable by day 13 using enrichment and PCR or plating. In conclusion, C. jejuni and E. coli O157:H7 declined on fresh kale over time when held at refrigerated temperatures but were still detected during the majority of the time when the kale would likely still be considered edible by consumers.
Inspired by natural creatures, such as spider silk, scientists have designed various bionic materials with special wettability. Compared with two-dimensional and three-dimensional materials, one-dimensional materials, such as fiber, with special wettability can dynamically transport or manipulate liquid droplets, attracting widespread attention. This paper reviews the latest developments of bioinspired fibers in the directional steering and transportation of droplets. Firstly, some fundamental theories of droplet's directional motion are reviewed. The movement of liquid droplets on the fiber is usually affected by several factors/features of the artificial fibers. Then the advantages and disadvantages of four representative methods for preparing bioinspired fibers with different features are reviewed. Subsequently, this paper continues to analyze the influencing factors of bioinspired fibers for efficient water collection and droplet driving direction, and the advantages of different structural combinations. Specifically, a section was dedicated to discuss droplets detachment from fibers. Finally, we provide some improved ideas and outlooks for developing of one-dimensional bioinspired fibers.
Fresh-cut vegetables are minimally processed healthy products that have gained the preference of consumers in accordance to the current lifestyle. Fresh-cut industry is continuously evolving and pursuing new varieties of raw material to develop innovative vegetable products, which fulfil consumer expectations. The current study evaluated the phenolic compounds in an innovative vegetable mix (red cabbage, rocket, parsley and beet greens) as well as their antioxidant capacity and bioaccessibility during their shelf life under refrigerated storage. The initial total phenolic compound and flavonoids content in the salad mixture were 163.3 ± 5.77 mg GAE/100 g FW and 280.96 ± 25.14 mg QE/100 g FW, respectively. The initial antioxidant capacity in the salad mixture was 85.4 ± 7.9 mg TE/100 g FW for DPPH and 318.1 ± 26.5 mg TE/100 g FW for ABTS assays. After digestion, total phenolic compound and TEAC capacity at initial times showed percentage of recovery values close to the chemical extraction and suffered a decrease towards day 10 of storage. Flavonoids and DPPH capacity showed recovery percentages less than 50%, at all storage times. Regarding sensory quality, the shelf-life of the salad mixture was limited by the presence of unacceptable off-odors at day 7 but since at microbiological evaluation, the shelf-life of the product is no longer than 5 days.
Fruits and vegetables (F&V) provide people with a variety of essential vitamins, antioxidants and dietary fibre, thus constituting integral components of human diet. With the surge of interest in F&V, their consumption ratio has kept increasing in recent years. Unfortunately, microorganisms and pesticide residues on the surfaces of F&V may be hazardous to humans. As an emerging technology, electrolysed water (EW) shows great application potential in reducing these hazards. EW treatment not only effectively removes microorganisms from F&V but also degrades pesticide residues on their surfaces. In addition, EW treatment affects the physiological metabolism of harvested F&V, which is conducive to maintain their sensory quality and nutritional value. This article reviews the principles of EW preparation, advantages and disadvantages, and the application of EW in F&V in the last decade, including disinfection of irrigation water, removal of pesticide residues, disinfection after harvest its effects on physicochemical parameters and enzyme activity of F&V, etc. Moreover, the combination of EW and other technology, including ozone, short‐time heat treatment, ultraviolet irradiation and ultrasound, to further improve the quality control effects of F&V is discussed.
Fruits and vegetables deteriorate mostly due to microbial and enzymatic activity during
postharvest storage. The objective of the work was to see if electrolyzed water and ultrasound can be applied combinedly in the industry to extend the shelf life of harvested fruits and vegetables. Ultrasound is a novel postharvest treatment method that has the potential to inactivate enzymes and microbes. Pectinmethylesterase, polygalacturonase, peroxidase, polyphenoloxidase, and lipoxygenase are the enzymes that are most commonly deactivated by ultrasound in fruits and vegetables. On the contrary, electrolyzed water is a potential antibacterial agent for fresh fruits and vegetables. Electrolyzed water treatment has some limitations in terms of microbial load reduction, which can be solved using sonication. This article deeply looked into the principles, advantages, disadvantages, and mechanism of action of both techniques.
Novelty impact statement: Individual and synergistic effects on shelf life extension of fruits and vegetables were reviewed. In addition, the inactivation mechanisms of microorganisms and enzymes of fruits and vegetables have been explained.
Fruits and vegetables deteriorate mostly due to microbial and enzymatic activity during postharvest storage. The objective of the work was to see if electrolyzed water and ultrasound can be applied combinedly in the industry to extend the shelf life of harvested fruits and vegetables. Ultrasound is a novel postharvest treatment method that has the potential to inactivate enzymes and microbes. Pectinmethylesterase, polygalacturonase, peroxidase, polyphenoloxidase, and lipoxygenase are the enzymes that are most commonly deactivated by ultrasound in fruits and vegetables. On the other hand, electrolyzed water is a potential antibacterial agent for fresh fruits and vegetables. Electrolyzed water treatment has some limitations in terms of microbial load reduction, which can be solved using sonication. This article deeply looked into the principles, advantages, disadvantages, and mechanism of action of both techniques.
The thermosonication processing has been evaluated as a smart alternative to overcoming the heat treatment limitations associated with longer holding times at high temperatures. In this regard, this innovative technique combines acoustic energy with moderate heat treatments to inactivate pathogenic and spoilage microorganisms and endogenous enzymes in foods and beverages. Thermosonication treatment employs short holding times, which can promote the maintenance of phytochemical compounds and sensory characteristics of food products. The challenges and advantages of this emerging technology were reviewed in contrast to conventional heat treatments. Additionally, the process design of ultrasound combined with mild thermal treatments was discussed. Thermosonication is presented as a promising technique to inactivate microorganisms and enzymes. Also, it has not affected the nutritional and sensory quality of different food products. However, thermosonication treatments must be standardized. Some studies used only acoustic cavitation as a source of heat. Furthermore, many studies did not calculate or present the actual thermal energy provided by thermosonication processes. Therefore, temperature monitoring throughout thermosonication processing is crucial to ensure the suitable process design, avoiding the negative impacts observed in thermally treated products, such as degradation of bioactive compounds and off-flavors formation.
Fresh-cut asparagus is susceptible to spoilage and quality deterioration during storage, which seriously affects its shelf-life and commercial value. The effects of ultrasonic-assisted citric acid and nisin washing (CNUS) combined with cinnamon essential oil fumigation (CEO) on microbial growth, physiological quality, and sensory characteristics of fresh-cut asparagus during storage at 4 °C were evaluated. The results showed that CNUS treatment immediately reduced the initial microbial load, and CEO treatment inhibited microbial growth during storage. CNUS + CEO treatment efficiently reduced the microbial counts and maintained acceptable levels for 20 d. In addition, CNUS + CEO treatment reduced respiration rate and weight loss, delayed respiration peak time, and maintained high ascorbic acid, chlorophyll and total soluble solids contents. Moreover, CNUS + CEO treatment greatly retarded lignin deposition by inhibiting phenylalanine ammonia lyase and peroxidase activities. CNUS + CEO treated samples had the lowest electrolyte leakage. The CNUS + CEO treatment could maintain the sensory characteristics and the shelf-life of fresh-cut asparagus for 20 d at 4 °C. Therefore, CNUS + CEO treatment could be used as an effective combination preservation technique for fresh-cut asparagus.
In the present study, the bactericidal efficacy of slightly acidic electrolyzed water (SAEW) against L. monocytogenes planktonic cells and biofilm on food-contact surfaces including stainless steel and glass was systematically evaluated. The results showed that SAEW (pH of 5.09 and available chlorine concentration (ACC) of 60.33 mg/L) could kill L. monocytogenes on food-contact surfaces completely in 30 s, whose disinfection efficacy is equal to that of NaClO solutions (pH of 9.23 and ACC of 253.53 mg/L). The results showed that long exposure time and high ACC contributed to the enhancement of the disinfection efficacy of SAEW on L. monocytogenes on food-contact surfaces. Moreover, the log reduction of SAEW treatment presented an increasing tendency within the prolonging of treatment time when SAEW was used to remove the L. monocytogenes biofilm formed on stainless steel and glass surfaces, which suggested that SAEW could remove L. monocytogenes biofilm effectively and its disinfection efficacy is equal to (in case of stainless steel) or higher than (in case of glass) that of high ACC of NaClO solutions. In addition, the results of the crystal violet staining and scanning electron microscopy (SEM) also demonstrated that SAEW treatment could remove the L. monocytogenes biofilm on food-contact surfaces.
As one of the most promising sterilization agents for microbial control in food industry in recent decades, electrolyzed water (EW) can be produced from diluted NaCl solution, and exhibits strong broad-spectrum bactericidal efficiency due to the synergistic effect of available chlorine concentrations, pH and oxidation reduction potential. To date, numerous studies have demonstrated the antimicrobial activity of EW against various kinds of microorganisms both in vitro and in vivo. However, the exact antimicrobial mechanisms of EW have not been determined at present, limiting its widespread application. In this review, we provide an overview of latest production equipment of EW, and briefly summarize the current advances of germicidal factors and antimicrobial mechanisms of electrolyzed water on different states of microorganisms. In addition, studies about hurdle enhancement of EW combined with other technologies are also discussed, providing guidelines for improving food safety and food quality both in conventional and organic food industry.
The disinfection efficacy of slightly acidic electrolyzed water (SAEW) has been recognized in food industry. However, the application of single SAEW limited its disinfection potential. The efficacy of the two-step disinfection with SAEW for the reduction of L. monocytogenes contamination on different food raw materials was evaluated compared to the one-step disinfection with SAEW in this study. Results demonstrated that SAEW could reduce both the natural aerobic bacterial count and inoculated L. monocytogenes population on endive and chicken immediately after processing and SAEW with approximately 60 mg/L of available chlorine concentration (ACC) had equal or higher antibacterial efficacy compared to NaClO solutions with approximately 150 mg/L of ACC. Moreover, SAEW treatments could control the growth of microbial populations of L. monocytogenes during storage and the efficacy on the microbial reduction was associated to the initial populations. In addition, the SAEW-treated food raw materials were stored and disinfected again after storage and the results showed that the two-step disinfection method could decrease the survival populations of L. monocytogenes by 24.8%∼99.6% compared to the one-step disinfection of SAEW. Therefore, considering storage habits, the two-step disinfection of SAEW may be a better choice in the disinfection of non-consumed-directly food raw materials.
Physicochemical and microbiological properties of pork chops sprayed with Neutral Electrolyzed Water (NEW) were evaluated during storage at refrigeration temperature. Pork chops were randomly allocated into three groups and were artificially contaminated with an inoculum of 10⁶ CFU/mL of Listeria monocytogenes. Each group was treated with either NEW (58 ppm), NaClO (35 ppm), or saline solution (SS). Subsequently, recovered bacteria were plated on TSA petri dishes and the reduction percentage of Listeria monocytogenes was calculated 24 h and 8 days after treatment. Physicochemical analysis [pH, content of lactic acid, thiobarbituric acid reactive substances (TBARS) and total volatile base nitrogen (TVBN)] were performed to evaluate the effect of all solutions used on pork meat kept at 4 °C for 19 days. In vitro NEW reduced L. monocytogenes titers by > 99.98% and 80.19% and 90.35% in artificially contaminated pork 24 h and 8 days after NEW treatment, respectively. Compared to the SS treatment, NEW and NaClO solutions caused a 0.67 Log UFC/g and 0.65 Log UFC/g reduction respectively. After eight days post-treatment, NEW and NaClO bacterial titers were below the SS treatment. NEW caused little color change in treated meat. It helped to reduce the formation of lactic acid and TVB-N when pork chops are kept at 4 °C for 19 days. Therefore, NEW could be considered as a new alternative to sanitize and preserve pork meat.
Biological creatures with unique surface wettability have long served as a source of inspiration for scientists and engineers. More specifically, certain beetle species in the Namib desert have evolved to collect water from fog on their backs by way of wettability patterns, which attracted an ongoing interest in biomimetic studies. Bioinspired materials exhibiting extreme wetting properties, such as superhydrophilic and superhydrophobic surfaces, have attracted considerable attention because of their potential use in various applications. However, combining these two extreme states of superhydrophilicity and superhydrophobicity on the same surface in precise two-dimensional micropatterns opens exciting new functionalities and possibilities in a wide variety of applications. In this review we briefly describe the corresponding water-harvesting mechanisms of Namib desert beetle, consisting of the theory of wetting and transporting. Then the methods for fabricating superhydrophilic-superhydrophobic patterns and highlight some of the newer and emerging applications of these patterned substrates that are currently being explored. Finally, conclusions and outlook concerning the future development of bioinspired surfaces of patterned wettability are presented.
Listeria monocytogenes may be present in produce-associated environments (e.g., fields, packing houses); thus, understanding its growth and survival on intact, whole produce is of critical importance. The goal of this study was to identify and characterize published data on the growth and/or survival of L. monocytogenes on intact fruit and vegetable surfaces. Relevant studies were identified by searching seven electronic databases: AGRICOLA, CAB Abstracts, Center for Produce Safety funded research project final reports, FST Abstracts, Google Scholar, PubMed, and Web of Science. Searches were conducted using the following terms: Listeria monocytogenes, produce, growth, and survival. Search terms were also modified and “exploded” to find all related subheadings. Included studies had to be prospective, describe methodology (e.g., inoculation method), outline experimental parameters, and provide quantitative growth and/or survival data. Studies were not included if methods were unclear or inappropriate, or if produce was cut, processed, or otherwise treated. Of 3,459 identified citations, 88 were reviewed in full and 29 studies met the inclusion criteria. Included studies represented 21 commodities, with the majority of studies focusing on melons, leafy greens, berries, or sprouts. Synthesis of the reviewed studies suggests L. monocytogenes growth and survival on intact produce surfaces differ substantially by commodity. Parameters such as temperature and produce surface characteristics had a considerable effect on L. monocytogenes growth and survival dynamics. This review provides an inventory of the current data on L. monocytogenes growth and/or survival on intact produce surfaces. Identification of which intact produce commodities support L. monocytogenes growth and/or survival at various conditions observed along the supply chain will assist the industry in managing L. monocytogenes contamination risk.
HIGHLIGHTS
Ultrasound (US) processing has emerged as a novel food preservation technology. This strategy has proved antimicrobial effects due to cavitation, which is the formation, growth, and collapse of bubbles that generate a localized mechanical and chemical energy. This technology can be applied by water so introducing it in the washing step to obtain safe fresh or fresh-cut products could be promising. The current review provides an overview of the current knowledge and recent findings on the use of US, alone or in combination with other mild physical technologies or chemical agents, to reduce microbial loads, and to better retain their quality attributes including color and texture, as well as the content of bioactive compounds such as antioxidant, phenolic compounds, or vitamins of minimally processed fruits and vegetables. As the effects of US depends on several factors related with treatment parameters, target microorganism, and matrix characteristics, further research efforts should be directed on optimizing US processes in accordance with their further application.
In this study, a total of 195 samples including fresh produce and farming environments was used to perform the microbial risk assessment. Levels of total aerobic bacteria ranged from 2.77 to 5.99, 6.28 to 7.81, and 1.31 to 2.74 log10 CFU/g, whereas levels of coliforms were ≤ 2.48, ≤ 3.35, and ≤ 0.85 log10 CFU/g, levels of Escherichia coli were ≤ 1.04, ≤ 0.12, and ≤ 1.69 log10 CFU/g in fresh produce, soil, and irrigation water, respectively. When the presence of pathogenic bacteria was detected, only Bacillus cereus and Staphylococcus aureus were isolated from 14 (7.2%) and 7 (3.6%) samples out of 195 samples, respectively. From the results, it was difficult to find a strong correlation between microbial contamination of fresh produce and their farming environments. However, continuous monitoring of agricultural products and related environments should be undertaken in order to ensure the microbial safety of fresh produce.
As food industry flourished, the use of EW as a novel sanitizing agent has gained interest worldwide. The chapter reviews recent progress in the application of EW in fruits and vegetables industry, summarizing its efficacy on disinfection and pesticide removal during their processing, and disease control along with inhibiting moth infestation throughout storage as well as the effect on physiochemical properties, chemical components, and postharvest physiology. Furthermore, it specially generalized the application of EW in the field of sprouts vegetables (our researching focus) to open up a new way for the development of functional food. It indicated that EW has sufficient obliterating efficacy on spoilage or pathogenic microorganisms, pesticide residues, and some insect pests existing on fruits and vegetables without compromising sensory and nutritional quality of them in most occasions. Besides, the employment of EW to sprouts vegetables makes those healthful components such as CABA and flavonoids accumulated. However, optimal processing parameters such as washing time along with physiochemical properties of EW need further selection. And, hurdle technology should not be tolerated to maximize treatment efficacy and prolong the shelf life of fresh produce. In brief, EW has a promising prospect in future utilization of fruits and vegetables.
Foods of animal origin, such as red meat and poultry products, are primary sources of superior protein for humans. With the production and consumption of these products increasing rapidly in recent decades, microbial safety and food quality are vital issues. Electrolyzed water (EW) as a sanitizer has awakened high interest in the food industry of many countries. The use of EW to decontaminate fresh red meat, ready-to-eat meat, poultry and shell eggs has been effective in reducing pathogenic microorganisms. Moreover, EW presents many advantages over traditional decontaminants; it provides effective antimicrobial activity and is environmentally friendly, simple to handle and relatively inexpensive. However, no complete elimination of pathogens on red meat and chicken meat was obtained after treatment of the meats with EW. This result probably occurs because organic matter and blood residue were present. This chapter provides a brief overview of how EW treatment affects foods of animal origin, especially the microbial safety and the physicochemical and sensory qualities of the food.
Improving the quality and safety aspects of fresh produce is one of the key issues in the food industry. EW is one of the most widely used sanitizers and is considered as an alternative technology to sodium chlorite treatment in the fresh produce industry. EW is well known to have a potential of microbial reduction of approximately 2 log CFU. The potential of this enhancement requires the application of combinations of EW with appropriate technologies susceptible to promoting standards in both microbial quality and safety and the sensory properties of fresh produce. In recent years, an increasing number of publications have shown that EW hurdle technology is considered as a potential food decontamination process, which can improve the microbial quality and safety and extend the shelf life of fresh produce. This chapter presents a complete picture of recent developments in EW hurdle technology applied to fresh produce, with a particular emphasis on microbial quality and safety. Several studies have been conducted to develop effective combined treatments of EW and thermal, chemical (especially organic), physical nonthermal, and various biological technologies. More specifically, the common use of chemical and biological treatments in simultaneous combination and the use of physical treatments in subsequent combination with different types of EW, including alkaline, acidic, and slightly acidic, are highlighted. The principles, mechanism of microbial and enzymatic inactivation, and microbial decontamination issues that can be overcome using a combination of EW with other treatments are also discussed. There are indications that the hurdle technology of EW can be used in the fresh produce industry; however, a better understanding of practical knowledge and the optimization of parameters of different treatments associated with EW would also contribute to reinforcing the future application of EW hurdle technologies in the fresh produce industry.
Electrolyzed oxidizing water (EOW) can be divided into acidic electrolyzed oxidizing water (AEOW) and slightly acidic electrolyzed water (SAEW). AEOW has the characteristics of low pH (pH < 2.7) and high oxidation-reduction potential (ORP > 1100 mV). SAEW is slightly acidic (pH = 5-6) and has an ORP of 700-900 mV. AEOW and SAEW both have a certain amount of active chlorine content (ACC), so they have the characteristics of broad spectrum, rapidity and high efficiency of sterilization. At present, there is little systematic research on AEOW and SAEW preparation. However, it is very important to study the preparation process, including electrode material and electrolytic process. First, the effects of Pt electrodes with different thermal decomposition temperatures on AEOW's pH, ORP and ACC values were investigated in detail. Next, for the SAEW preparation, the process is based on the preparation of AEOW by ion-exchange membrane electrolysis, reasonably mixing the electrolyzed cathode and anode solution. The effects of technological conditions such as electrolysis time, current density and electrolyte concentration have been systematically studied, and it is expected to get SAEW with a pH value slightly less than 7, a higher ORP value and a certain amount of ACC.
Decontamination of fresh fruits and vegetables is an important unsolved technological problem. The main focus of this review is to summarize and synthesize the results of studies and articles about ultrasonic processing which can be adapted to the wash water decontamination process for fruits and vegetables. This review will also provide an overview about the importance of an effective wash water decontamination process in fruits and vegetables, the increase of foodborne outbreaks caused by fresh fruits and vegetables, microbial inactivation using ultrasound, and an interpretation of the high power ultrasound results in the fruits and vegetable industry. In addition, the limitations of ultrasonic processing in commercial applications have also been introduced.
In this study, the cold chain and its impact on food stuff microbiology was evaluated for fresh-cut endive. A survey was carried out to analyze endive temperature throughout the supply chain from producer, via processor and distributor to the restaurant. Data loggers accompanying the endive on its route provided a temperature profile of the endive. The effect of the outdoor temperature on initial cooling was evaluated and critical points regarding cold chain management in the supply chain were identified. Our experiments indicate that the cold chain is generally properly maintained. In parallel with temperature monitoring, indicator microorganisms were assessed at different points in the supply chain to examine the effects of endive temperature, temperature fluctuations, and the outdoor temperature on microbial food safety. Small temperature fluctuations in the supply chain had a small effect on the total level of aerobic mesophilic bacteria. However, at the best before-date, total coliforms and Enterobacteriaceae levels were significantly higher in endive samples subject to temperature fluctuations in the supply chain, compared to endive stored in optimal conditions. To our knowledge, this is the first study that combines microbiological analysis with the temperature profile of fresh-cut produce in a realistic food supply chain.
Five nationally and regionally distributed brands of ready-to-eat salads in sealed bags were sampled from major supermarket chains. At time of purchase, product temperature was 4 to 7 degrees C; the mean mesophilic microbial population was 1.0 x 10(7) CFU/g; the yeast population was 210 CFU/g; the mean headspace O2 and CO2 concentrations were 1.2 and 12%, respectively; and the ethanol content was 700 ppm. For samples analyzed on the expiration date (14 to 16 days after packaging) the mean mesophilic microbial population was 6 x 10(7) CFU/g; ethanol content was 1,500 ppm; and the headspace gas had not markedly changed from time of purchase.
Nitrogen (N2) gas packaging for fresh-cut vegetables (lettuce and cabbage) has been examined as a means of modified atmosphere packaging (MAP) for extending the shelf life of cut vegetables. Gas composition in enclosed packages that contained cut vegetables and were filled with 100% N2 had an oxygen (O2) concentration of 1.2 to 5.0% and a carbon dioxide (CO2) concentration of 0.5 to 3.5% after 5 days of storage. An atmosphere of low concentrations of O2 and high CO2 conditions occurred naturally in the package filled with N2 gas. Degradation of cut vegetables in terms of appearance was delayed by N2 gas packaging. Because of this effect, the appearance of fresh-cut vegetables packaged with N2 gas remained acceptable at temperatures below 5 degrees C after 5 days. Treatment with acidic electrolyzed water (AcEW) contributed to the acceptability of the vegetables' appearance at 5 and 10 degrees C in the air-packaging system. N2 gas packaging did not significantly affect the growth of microbial populations (total aerobic bacteria, coliform bacteria, Bacillus cereus, and psychrotrophic bacteria) in or on cut vegetables at 1, 5, and 10 degrees C for 5 days. Microbial growth in or on the cut vegetables was inhibited at 1 degrees C for 5 days regardless of atmospheric conditions.
Several sigmoidal functions (logistic, Gompertz, Richards, Schnute, and Stannard) were compared to describe a bacterial growth curve. They were compared statistically by using the model of Schnute, which is a comprehensive model, encompassing all other models. The t test and the F test were used. With the t test, confidence intervals for parameters can be calculated and can be used to distinguish between models. In the F test, the lack of fit of the models is compared with the measuring error. Moreover, the models were compared with respect to their ease of use. All sigmoidal functions were modified so that they contained biologically relevant parameters. The models of Richards, Schnute, and Stannard appeared to be basically the same equation. In the cases tested, the modified Gompertz equation was statistically sufficient to describe the growth data of Lactobacillus plantarum and was easy to use.
Recent foodborne outbreaks implicating spinach and lettuce have increased consumer concerns regarding the safety of fresh produce. While the most common commercial antimicrobial intervention for fresh produce is wash water containing 50 to 200 ppm chlorine, this study compares the effectiveness of acidified sodium chlorite, chlorine, and acidic electrolyzed water for inactivating Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes inoculated onto leafy greens. Fresh mixed greens were left uninoculated or inoculated with approximately 6 log CFU/g of E. coli O157:H7, Salmonella, and L. monocytogenes and treated by immersion for 60 or 90 s in different wash solutions (1:150, wt/vol), including 50 ppm of chlorine solution acidified to pH 6.5, acidic electrolyzed water (pH 2.1 +/- 0.2, oxygen reduction potential of 1,100 mV, 30 to 35 ppm of free chlorine), and acidified sodium chlorite (1,200 ppm, pH 2.5). Samples were neutralized and homogenized. Bacterial survival was determined by standard spread plating on selective media. Each test case (organism x treatment x time) was replicated twice with five samples per replicate. There was no difference (P > or = 0.05) in the time of immersion on the antimicrobial effectiveness of the treatments. Furthermore, there was no difference (P > or = 0.05) in survival of the three organisms regardless of treatment or time. Acidified sodium chlorite, resulted in reductions in populations of 3 to 3.8 log CFU/g and was more effective than chlorinated water (2.1 to 2.8 log CFU/g reduction). These results provide the produce industry with important information to assist in selection of effective antimicrobial strategies.
This study evaluated the efficacy of individual treatments (thermosonication [TS+DW] and slightly acidic electrolyzed water [SAcEW]) and their combination on reducing Escherichia coli O157:H7, Listeria monocytogenes, and spoilage microorganisms (total bacterial counts [TBC], Enterobacteriaceae, Pseudomonas spp., and yeast and mold counts [YMC]) on fresh-cut kale. For comparison, the antimicrobial efficacies of sodium chlorite (SC; 100 mg/L) and sodium hypochlorite (SH; 100 mg/L) were also evaluated. Each 10 g sample of kale leaves was inoculated to contain approximately 6 log CFU/g of E. coli O157:H7 or L. monocytogenes. Each inoculated or uninoculated samples was then dip treated with deionized water (DW; control), TS+DW, and SAcEW at various treatment conditions (temperature, physicochemical properties, and time) to assess the efficacy of each individual treatment. The efficacy of TS+DW or SAcEW was enhanced at 40 °C for 3 min, with an acoustic energy density of 400 W/L for TS+DW and available chlorine concentration of 5 mg/L for SAcEW. At 40 °C for 3 min, combined treatment of thermosonication 400 W/L and SAcEW 5 mg/L (TS+SAcEW) was more effective in reducing microorganisms compared to the individual treatments (SAcEW, SC, SH, and TS+DW) and combined treatments (TS+SC and TS+SH), which significantly (P < 0.05) reduced E. coli O157:H7, L. monocytogenes, TBC, Enterobacteriaceae, Pseudomonas spp., and YMC by 3.32, 3.11, 3.97, 3.66, 3.62, and >3.24 log CFU/g, respectively. The results suggest that the combined treatment of TS+SAcEW has the potential as a decontamination process in fresh-cut industry.
© 2015 Institute of Food Technologists®
The effect of non-thermal technologies (ozone in aqueous solution, ultrasound and ultraviolet C radiation) and washings with chemical solutions (sodium hypochlorite and hydrogen peroxide) on safety and quality features of strawberries was studied. These treatments were applied before fruit storage at two different temperatures (4 and 15 °C). The overall impact on microbial loads (total mesophiles, and yeasts and moulds) and selected quality attributes (colour, firmness, pH, total anthocyanins and ascorbic acid content) was assessed.During storage under refrigerated temperature, washing with hydrogen peroxide solutions resulted in strawberries with lower microbial loads, when compared to the other treatments. However, it produced significant key quality attributes losses, such as colour and total anthocyanins content.The results presented show that ozone and ultrasound are promising alternatives to thermal treatments. The application of such technologies, before refrigerated storage of strawberries, allowed a satisfactory retention of all quality characteristics analysed, while being efficient in controlling microbial contamination.
The importance of bacterial pathogens in the transmission of foodborne illness has become apparent in recent years. Several large, well-publicized outbreaks of foodborne illness have been linked to cantaloupe, tomatoes, lettuce, alfalfa sprouts, and both apple and orange juices. In addition, numerous other smaller scale outbreaks linked to these and other commodities have also been reported. Although contributing factors have not been determined in all cases, several notable causes have been proposed. In particular, cross contamination with fecal matter of both domestic as well as wild animals have been suggested. In addition, contact with contaminated water has also been identified as a source of contamination. However, the use of untreated manure or sewage, lack of field sanitation, poorly or unsanitized transportation vehicles, and contamination by handlers are also suggested as potential contributing factors. Control of foodborne pathogens in produce must begin before produce is even planted by avoiding fields which have been subjected to flooding, on which animals have been recently grazed, or have otherwise been contaminated with manure. After planting, only clean potable water should be used for irrigation and harvesting equipment should be thoroughly cleaned and sanitized. Both field workers and packinghouse and processing plant personnel should be instructed in proper personal hygiene and provided with adequate sanitary and handwashing facilities. Vehicles transporting finished products should be sanitized, properly loaded to provide adequate air circulation, and maintained at proper temperatures. Likewise, retail display cases must be kept clean and at proper refrigeration temperatures. Finally, consumers should be informed as to proper handling of produce, particularly in the case of new generation products such as modified atmosphere packaged produce.
Neutral (NEW) and acidic (AEW) electrolyzed water were stored in open or closed glass bottles under light or dark conditions at 20 °C for 30 days. The pH, oxidation–reduction potential (ORP), electrical conductivity (EC), available chlorine concentration (ACC), dissolved oxygen (DO), and bactericidal efficiency of NEW and AEW were determined during storage or before and after storage, respectively. The pH and EC of NEW and AEW remained unchanged in storage. The ORP, ACC and DO of AEW decreased 22%, 100% and 52% under open storage conditions, respectively. Light had no significant effects on the physicochemical properties of NEW (P > 0.05). Bactericidal efficiency was not markedly affected by storage conditions for NEW, but decreased significantly for AEW under open storage conditions. Electrolyzed water should be stored in closed containers or used immediately to prevent the loss of available chlorine that is one of the main contributing factors for antimicrobial activity.
Minimally processed vegetables (MPV) are economically important commodities due to a combination of factors such as convenience, healthiness and desirable sensory characteristics. These commodities are susceptible to microbiological invasion due to the presence of cut surfaces causing both microbiological and physiological mechanisms to be possible limitations for the sensory shelf life. This review evaluates the role of microbiological activity in the development and changes of different sensory quality factors (visual, flavour, and textural quality) of minimally processed vegetables and evaluates the possible interaction with physiological mechanisms, taking into account important preservation techniques such as storage temperature and atmospheric conditions.
Exposure to superatmospheric O2 concentration may stimulate, have no effect, or reduce rates of respiration and ethylene production, depending on the commodity, maturity and ripeness stage, O2 concentration, storage time and temperature, and concentrations of CO2 and C2H4 present in the atmosphere. In some plant organs, cyanide-resistant respiration is enhanced by elevated O2 atmospheres. Ripening of mature-green, climacteric fruits was slightly enhanced by exposure to 30–80 kPa O2, but levels above 80 kPa retarded their ripening and caused O2 toxicity disorders on some fruits. High O2 concentrations enhance some of the effects of ethylene on fresh fruits and vegetables, including ripening, senescence, and ethylene-induced physiological disorders (such as bitterness of carrots and russet spotting on lettuce). While superatmospheric O2 concentrations inhibit the growth of some bacteria and fungi, they are much more effective if combined with elevated (15–20 kPa) CO2, which is a fungistatic gas.
The aim of this work was to investigate the use of different doses of UV-C (0, 2.4, 7.2, 12 and 24 kJ m−2) radiation treatments to inhibit microbial growth of Listeria monocytogenes and Salmonella enterica. The spoilage bacteria Pseudomonas marginalis (gram negative) was also tested. These bacteria were studied under in vitro conditions and in baby spinach leaves (in vivo conditions) for 13 and 14 d at 5 °C, respectively. All radiation doses were effective in reducing bacterial growth, although contrary to expectations, high doses did not show the highest microbial inhibition in in vitro experiments. UV-C doses (2.4–24 kJ m−2) were also used on baby spinach (Spinacia oleracea L.) leaf surfaces, stored under humidified air using perforated plastic film. A clear inhibitory UV-C effect was observed on L. monocytogenes for 14 d at 5 °C. Meanwhile, UV-C radiation reduced S. enterica loads until the first 4 d of storage, after which a significant increase was found on radiated leaves compared to the control. P. marginalis counts were slightly reduced in UV-C treated leaves. In addition, significant decreases in psychrotrophic counts and Enterobacteriaceae were found during the first 4 d of storage. Respiration rates of baby spinach leaves were higher in radiated than in non-radiated leaves. Moreover, no obvious damage on the epidermal surface and to cell shape was detected in radiated and non-radiated leaves by scanning electronic microscopy (SEM). In summary, the use of double-sided UV-C radiation, at low doses, was effective in reducing initial microbial counts of the tested bacteria types and psychrotrophic and Enterobacteria counts, and in keeping L. monocytogenes at low levels during the storage period, without affecting the sensory quality of fresh-cut baby spinach leaves.
Fresh-cut cilantro is particularly susceptible to microbial growth and, therefore, use of an effective sanitizer on this product is of great importance. The objective of this study was to evaluate the efficacy of different sanitizing treatments on reducing Escherichia coli O157:H7 populations, aerobic mesophilic bacterial, yeast and mould counts on fresh-cut cilantro. Cut cilantro was treated with sodium hypochlorite (SH) at 0.2 g L−1 free chlorine and acidified sodium chlorite (ASC) at 0.1, 0.25, 0.5 and 1 g L−1, along with the components of ASC, i.e., citric acid (CA) at 6 g L−1 and sodium chlorite (SC) at 1 g L−1. In the present study, it was found that SH inactivated, at maximum, 1–1.3 log cfu g−1 of background or pathogenic microflora present on cut cilantro. However, reductions of more than 3 log cfu g−1 were observed after washing with 1 g L−1 of ASC. Moreover, when lower concentrations of ASC were used (0.25 and 0.5 g L−1), microbial populations were reduced by about 2 log cfu g−1. SC was as effective as ASC at 1 g L−1 in reducing aerobic mesophilic bacteria and E. coli O157:H7 populations, although it was not as effective as ASC in reducing yeast and mould populations.
The aim of this review article is to describe an integrated approach to modern minimal processing of fresh produce. Current know-how on all of the steps involved in minimal processing of fresh produce from raw materials to packaged products is introduced. Shelf life and quality aspects of minimally processed produce are also presented.
It is well known that fresh-cut processors usually rely on wash water sanitizers to reduce microbial counts in order to maintain quality and extend shelf-life of the end product. Water is a useful tool for reducing potential contamination but it can also transfer pathogenic microorganisms. Washing with sanitizers is important in fresh-cut produce hygiene, particularly removing soil and debris, but especially in water disinfection to avoid cross-contamination between clean and contaminated product. Most of the sanitizing solutions induce higher microbial reduction after washing when compared to water washing, but after storage, epiphytic microorganisms grow rapidly, reaching similar levels. In fact, despite the general idea that sanitizers are used to reduce the microbial population on the produce, their main effect is maintaining the microbial quality of the water. The use of potable water instead of water containing chemical disinfection agents for washing fresh-cut vegetables is being advocated in some European countries. However, the problems of using an inadequate sanitizer or even none are considered in this manuscript. The need for a standardized approach to evaluate and compare the efficiency of sanitizing agents is also presented. Most new alternative techniques accentuate the problems with chlorine suggesting that the industry should move away from this traditional disinfection agent. However, the use of chlorine based sanitizers are presented as belonging to the most effective and efficient sanitizers when adequate doses are used. In this review improvements in water disinfection and sanitation strategies, including a shower pre-washing step and a final rinse of the produce, are suggested.
Minimally processed fresh (MPF) fruits and vegetables are good media for growth of microorganisms. They have been involved in outbreaks because of the consumption of products contaminated by pathogens. They are also sensitive to various spoilage microorganisms such as pectinolytic bacteria, saprophytic Gram-negative bacteria, lactic acid bacteria, and yeasts. Contamination of MPF fruits and vegetables occurs at every stage of the food chain, from cultivation to processing. Polluted environments during cultivation or poor hygienic conditions in processing increase the risk of contamination with foodborne pathogens. Although MPF fruits and vegetables may harbor psychrotrophic microorganisms such as fluorescent pseudomonads or Listeria monocytogenes, good control of refrigeration temperature limits growth of spoilage and pathogenic microorganisms. Modified atmospheres are often efficient to maintain or improve visual organoleptic quality of MPF fruits and vegetables, but their effects on microorganisms are inconsistent. Chemical disinfection can partially reduce the initial bacterial contamination; irradiation seems to be more efficient. The applications of legislations and quality assurance systems to control contamination, survival, and growth of foodborne pathogens in MPF fruits and vegetables are discussed.
The quality of four types of fresh-cut produce, packaged in consumer-sized packages under an equilibrium modified atmosphere and stored at 7 degrees C, was assessed by establishing the relation between the microbial outgrowth and the corresponding production of nonvolatile compounds and related sensory disorders. In vitro experiments, performed on a lettuce-juice-agar, demonstrated the production of nonvolatile compounds by spoilage causing lactic acid bacteria and Enterobacteriaceae. Pseudomonas fluorescens and yeasts, however, were not able to produce detectable amounts of nonvolatile metabolites. The type of spoilage and quality deterioration in vivo depended on the type of vegetable. Mixed lettuce and chicory endives, leafy tissues, containing naturally low concentrations of sugars, showed a spoilage dominated by Gram-negative microorganisms, which are not producing nonvolatile compounds. Sensory problems were associated with visual properties and the metabolic activity of the plant tissue. Mixed bell peppers and grated celeriac, on the other hand, demonstrated a fast and intense growth of spoilage microorganisms, dominated by lactic acid bacteria and yeasts. This proliferation resulted in detectable levels of organic acids and the rejection by the trained sensory panel was based on the negative perception of the organoleptical properties (off-flavour, odour and taste). The applied microbiological criteria corresponded well with detectable changes in sensory properties and measurable concentrations of nonvolatile compounds, surely in the cases where lactic acid bacteria and yeasts were provoking spoilage. Consequently, the freshness of minimally processed vegetables, sensitive for outgrowth of lactic acid bacteria and yeasts (e.g., carrots, celeriac, bell peppers, mixtures with non-leafy vegetables) can be evaluated via analysis of the produced nonvolatile compounds.
A limited survey of fresh and minimally processed vegetables, and sprouts was conducted in the Washington, DC area to determine if potentially toxigenic and pathogenic fungi were present in these commodities. Thirty-nine ready-to-eat salads, 29 whole fresh vegetables and 116 sprout samples (bean, alfalfa, broccoli, crunchy, garlic, spicy, onion, clover, lentil and multi-seed sprouts) were purchased from 13 local supermarkets and tested for yeast and mould counts as well as the presence of toxigenic moulds. Yeasts were the most prevalent organisms found in these samples, at levels ranging from less than 100 to 4.0x10(8) cfu/g. Mould counts generally ranged from less than 100 to 4.0x10(4) cfu/g. Two crunchy sprout samples, however, contained unusually high numbers of Penicillium (1.1x10(8) and 1.3x10(8) cfu/g), two alfalfa sprout samples contained Geotrichum populations about 10(6) cfu/g, and two alfalfa sprout samples had Cladosporium counts higher than 2.5x10(5) cfu/g. The most common moulds found in fresh and minimally processed vegetables were Cladosporium, Alternaria and Penicillium; less common was Geotrichum. The most frequently isolated moulds from sprouts were Alternaria, Cladosporium, Penicillium, and Phoma. Phoma was especially common in alfalfa sprouts. Fusarium, Rhizopus, Mucor, and Geotrichum were isolated less often.
Efficacy of acidified sodium chlorite for reducing the population of Escherichia coli O157:H7 pathogens on Chinese cabbage leaves was evaluated. Washing leaves with distilled water could reduce the population of E. coli O157:H7 by approximately 1.0 log CFU/g, whereas treating with acidified chlorite solution could reduce the population by 3.0 log CFU/g without changing the leaf color. A similar level of reduction was achieved by washing with sodium chlorite solution containing various organic acids. However, acidified sodium chlorite in combination with a mild heat treatment reduced the population by approximately 4.0 log CFU/g without affecting the color, but it softened the leaves. Moreover, the efficacy of the washing treatment was similar at low (4 degrees C) and room (25 degrees C) temperatures, indicating that acidified sodium chloride solution could be useful as a sanitizer for surface washing of fresh produce.
Minimally processed vegetables (MPV) have a short shelf-life. Neutral electrolysed oxidising water (NEW) is a novel decontamination method. The objective of this study was to test the potential of NEW to extend the shelf-life of a MPV, namely shredded cabbage. Samples of shredded cabbage were immersed in NEW containing 40 mg/L of free chlorine or tap water (control) up to 5 min, and then stored under equilibrium modified atmosphere at 4 degrees C and 7 degrees C. Proliferation of aerobic mesophilic bacteria, psychrotrophic bacteria, lactic acid bacteria and yeasts were studied during the shelf-life. Also pH and sensorial quality of the samples as well as O(2) and CO(2) composition of the headspace of the bags was evaluated. From the microbial groups, only psychrotrophic counts decreased significantly (P<0.05) due to the effect of NEW, but the counts in treated samples and controls were similar after 3 days of storage at 4 degrees C and 7 degrees C. Packaging configurations kept O(2) concentration around 5% and prevented CO(2) accumulation. pH increased from 6.1-6.2 to 6.4 during the shelf-life. No microbial parameter reached unacceptable counts after 14 days at 4 degrees C and 8 days of storage at 7 degrees C. The shelf-life of controls stored at 4 degrees C was limited to 9 days by overall visual quality (OVQ), while samples treated with NEW remained acceptable during the 14 days of the experiment. The shelf-life of controls stored at 7 degrees C was limited to 6 days by OVQ and browning, while that of samples treated with NEW were limited to 9 days by OVQ, browning and dryness. According to these results, a shelf-life extension of at least 5 days and 3 days in samples stored respectively at 4 degrees C and 7 degrees C can be achieved by treating shredded cabbage with NEW. NEW seems to be a promising method to prolong the shelf-life of MPV.
Food safety issues and increases in food borne illnesses have promulgated the development of new sanitation methods to eliminate pathogenic organisms on foods and surfaces in food service areas. Electrolyzed oxidizing water (EO water) shows promise as an environmentally friendly broad spectrum microbial decontamination agent. EO water is generated by the passage of a dilute salt solution ( approximately 1% NaCl) through an electrochemical cell. This electrolytic process converts chloride ions and water molecules into chlorine oxidants (Cl(2), HOCl/ClO(-)). At a near-neutral pH (pH 6.3-6.5), the predominant chemical species is the highly biocidal hypochlorous acid species (HOCl) with the oxidation reduction potential (ORP) of the solution ranging from 800 to 900mV. The biocidal activity of near-neutral EO water was evaluated at 25 degrees C using pure cultures of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Enterococcus faecalis. Treatment of these organisms, in pure culture, with EO water at concentrations of 20, 50, 100, and 120ppm total residual chlorine (TRC) and 10min of contact time resulted in 100% inactivation of all five organisms (reduction of 6.1-6.7log(10)CFU/mL). Spray treatment of surfaces in food service areas with EO water containing 278-310ppm TRC (pH 6.38) resulted in a 79-100% reduction of microbial growth. Dip (10min) treatment of spinach at 100 and 120ppm TRC resulted in a 4.0-5.0log(10)CFU/mL reduction of bacterial counts for all organisms tested. Dipping (10min) of lettuce at 100 and 120ppm TRC reduced bacterial counts of E. coli by 0.24-0.25log(10)CFU/mL and reduced all other organisms by 2.43-3.81log(10)CFU/mL.
Gaseous ClO2 was evaluated for effectiveness in prolonging the shelf-life of minimally processed (MP) lettuce and MP cabbage, previously immersed in a cysteine solution in order to inhibit browning occurring during ClO2 treatment. Each vegetable was shredded, washed, and separated in two portions, one to be treated with ClO2 gas and the other to remain untreated as reference sample. The batch to be treated with ClO2 gas was immersed for 1 min in a 0.5% solution of HCl.L-cysteine monohydrate. Then both batches were spun dried. MP vegetables were decontaminated in a cabinet at 90-91% relative humidity and 22-25 degrees C up to 10 min, including 30 s of ClO2 injection into the cabinet. The ClO2 concentration rose to 1.74 mg/L (MP lettuce) and 1.29 mg/L (MP cabbage). Then samples were stored under modified atmosphere at 7 degrees C for shelf-life studies. Changes in O2 and CO2 headspace concentrations, microbiological quality (aerobic plate count (APC), psychrotrophs, lactic acid bacteria, and yeasts), sensory quality, and pH were followed during storage. The respiration rate of the minimally processed vegetables was significantly increased by the ClO2 gas treatment only in the case of MP cabbage (P<0.05). The gas treatment reduced initially APC and psychrotroph count of MP lettuce and APC, psychrotroph counts, yeast counts and pH of MP cabbage (P<0.05). ClO2 treatment did not cause initially any significant (P<0.05) sensorial alteration, except for a weak off-odour in MP lettuce. Interestingly, no browning was observed after treating, which can be accounted to the use of L-cysteine. Although an initial microbiological reduction was observed due to ClO2 gas treatment, APC and psychrotroph counts reached in the samples treated with ClO2 higher levels than in those non-treated with ClO2 before the third day of the shelf-life study. Untreated and treated samples of MP lettuce were sensorial unacceptable due to bad overall visual quality after 4 days, while treated and untreated MP cabbage remained sensorial acceptable during the 9 days of the study. L-cysteine reduced (P<0.05) the decontamination efficacy of ClO2 when applied to MP cabbage but not in the case of MP lettuce. Gaseous ClO2 failed to prolong the shelf-life of MP lettuce and MP cabbage, the reason for the enhanced growth of microorganisms in decontaminated samples should be investigated. Nonetheless, our results prove that it is possible to inhibit browning caused by ClO2.
To evaluate the effect of 3-month kale (Brassica oleracea acephala) juice supplementation on coronary artery disease risk factors among hypercholesterolemic men.
Thirty-two men with hypercholesterolemia (> 200 mg/dL) were recruited after annual health examinations among the faculty and staff at university. The subjects consumed 150 mL of kale juice per day for a 12-week intervention period. Dietary and anthropometric assessments were performed and blood samples were collected to evaluate biochemical profiles before and after supplementation.
Serum concentrations of HDL-cholesterol, and HDL- to LDL-cholesterol ratio were significantly increased by 27% (P<0.0001) and 52% (P<0.0001), respectively. The LDL-cholesterol concentration and the atherogenic index were significantly reduced by 10% (P=0.0007) and 24.2% (P<0.0001), respectively without affecting body mass index, waist and hip circumferences, or nutrient intakes after three months of supplementation. While there was no difference in the concentration of malondialdehyde, significant increase in glutathione peroxidase activity (P=0.0005) were accompanied by a significant increase in the serum selenium level (P=0.0132). It was also found that the responses of these risk factors to kale juice administration were dependent on smoking status.
Regular meals supplementation with kale juice can favorably influence serum lipid profiles and antioxidant systems, and hence contribute to reduce the risks of coronary artery disease in male subjects with hyperlipidemia.
The Church of Superfoods Gains More Believers
- V Wong
Wong, V., 2014. The Church of Superfoods Gains More Believers. Available from:
http://www.businessweek.com/articles/2014-08-13/kale-and-the-church-ofsuperfoods-gains-more-believers (accessed 01.12.14.).
Microbial populations of fresh-cut spinach leaves affected by controlled atmospheres
- V H Escalona
- E Aguayo
- G B Martínez-Hern Andez
- F Art Es
Escalona, V.H., Aguayo, E., Martínez-Hern andez, G.B., Art es, F., 2010. Microbial
populations of fresh-cut spinach leaves affected by controlled atmospheres.
Postharvest Biol. Technol. 56, 223e231.
Shelf-life of minimally processed cabbage treated with neutral electrolysed oxidizing water and stored under equilibrium modified atmosphere
- G Omez-L Opez
- V M Ragaert
- P Ryckeboer
- J Jeyachchandran
- V Debevere
- J Devlieghere
G omez-L opez, V.M., Ragaert, P., Ryckeboer, J., Jeyachchandran, V., Debevere, J.,
Devlieghere, F., 2007. Shelf-life of minimally processed cabbage treated with
neutral electrolysed oxidizing water and stored under equilibrium modified
atmosphere. Int. J. Food Microbiol. 117, 91e98.