Article

Efficacy of sanitizers in reducing Escherichia coli O157:H7, Salmonella spp. and Listeria monocytogenes populations on fresh-cut carrots

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Abstract

Shredded carrots were inoculated with Escherichia coli O157:H7, Salmonella or Listeria monocytogenes and washed for 1 or 2 min with chlorine (Cl; 200 ppm), peroxyacetic acid (PA; 40 ppm) or acidified sodium chlorite (ASC; 100, 200, 500 ppm) under simulated commercial processing conditions. After washed, the carrots were spin dried, packaged and stored at 5 °C for up to 10 days. Bacterial enumeration was significantly (P ⩽ 0.05) reduced by 1, 1.5 and 2.5 log CFU/g after washing with ASC 100, 250 and 500 ppm, respectively. All sanitizers reduced pathogen load below that of tap water wash and unwashed controls. During storage at 5 °C the bacterial load of all treatments increased gradually, but to different extent in different treatments. ASC inhibited bacterial growth more effectively than the other sanitizers and also maintained the lowest pathogen counts (<1 log CFU/g) during storage. Organic matter in the process water significantly (P ⩽ 0.05) reduced the antibacterial efficacy of Cl, but not that of PA or ASC. Therefore, ASC shows the potential to be used as a commercial sanitizer for washing shredded carrots.

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... A nível mundial, o consumo anual de frutas e hortaliças apresentou um crescimento médio de 4,5% entre os anos de 1990 e 2004 (Olaimat e Holley, 2012) estando esse aumento relacionado com a preocupação em se manter uma dieta alimentar saudável (Warriner et al., 2009;Forghani e Oh, 2013). O aumento da procura por alimentos mais saudáveis, aliado às exigências do consumidor (Ruíz -Cruz et al., 2007;Alegre et al., 2011), e à conveniência proporcionada pelos alimentos prontos (Glowacz et al., 2013) contribuíram para o aumento do consumo de frutas e hortaliças minimamente processadas (Graça et al., 2011;Joshi et al., 2013). Entende -se por produtos minimamente processados as frutas e hortaliças frescos que foram submetidos a um processo tecnológico que incluiu as operações de limpeza, lavagem, descascasque, corte, ou não, desinfeção, centrifugação e embalagem em atmosfera modificada, ficando prontos para consumo ou para preparação imediata, sem que percam a condição de produto fresco. ...
... A FDA (Food and Drug Administration) estipulou que soluções contendo no mínimo 85 mg.L -1 de ácido peroxicético devem ser usadas na higienização e superfícies onde os alimentos são manipulados, onde a concentração pode variar até 300 mg.L -1 (Álvaro et al., 2009). Este mesmo órgão regulamentador aprovou a utilização de ácido peroxicético para a desinfecção de produtos vegetais em concentrações que não ultrapassem 80 mg.L -1 (Ruíz -Cruz et al., 2007). ...
... A utilização de ácido peroxiacético a 80 mg.L -1 durante de 5 minutos na desinfeção de coentros minimamente processado, demonstrou ter a possibilidade de substituir o dicloroisocianurato de sódio, devido a redução de cerca de 2 log UFC.g -1 da população de Escherichia coli (Srebernich, 2007). Ruíz -Cruz et al. (2007) avaliaram o efeito do ácido peroxiacético, na desinfeção de cenoura minimamente processada, e observaram uma redução significativa na população de Salmonella de cerca de 2,1 log UFC.g -1 . ...
Article
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The consumption of fruits and vegetables has increased with modern society seeking healthier lifestyles. Today consumers want fresh foods, with convenience and microbiological, sensory and nutritional quality. The microbiological quality of fruits and vegetables is related with the presence of spoilage microorganisms, which can reduce the shelf life of these products and the presence of pathogenic microorganisms that can cause illness in consumers. Washing step with sanitizers application is the stage which can be reduced microbial load to ensure safety product. Chlorinated compounds are widely used in descontamination, however, there is interest in using others since they generate toxic wastes, as trihalomethanes, in the presence of organic ma tter undergoing decomposition. Among the alternatives, the literature indicate the application of other chemical sanitizers such as hydrogen peroxide, peroxiacetic acid, chlorine dioxide, ozone, organic acids and physical descontaminating as ultrasound.
... Besides, Propionic, acetic, malic, citric, lactic and tartaric acid may be used for food disinfection purposes [4,10,14]. US Food and Drug Administration (FDA) approves the use of peroxyacetic acid (PAA) as a strong oxidant for sanitizing some food products like fruits and vegetables (concentration of PPA in washing water should not exceed 80 ppm) [15]. Low temperature during storage and atmospheric conditions including 3-8% CO 2 and 2-5% O 2 are recommended to maintain the freshness and extending fruits and vegetables shelf life for modified atmosphere packaging (MAP) storage [14,16,17]. ...
... The bacterial crowd in each cocktail culture was authenticated by plating 0.1 mL portions of appropriately diluted culture on TSA. Since the immersion process is a probable contamination location in the food industry, dip inoculation is the most appropriate procedure to imitate such an operation [15]. The grated carrots were immersed in the bacterial inoculum solution (inoculum ratio D1:5 w/v) and stirred for 2 min. ...
... Dehydration of the carrot samples during storage and lignin development caused increase in whiteness index (15,18). The grated carrots packaged in polypropylene containing nano-clay hydrophilic bentonite showed lower (P < 0.05) WI* values comparing to the control samples which were in agreement with the results obtained for L* values, and indicated an effective control over development of surface discoloration on the grated carrots. ...
Article
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... Efektywność działania podchlorynu sodu silnie zależy również od czasu kontaktu z produktem, temperatury i rodzaju wody -wykazuje on zdecydowanie lepsze działanie bakteriobójcze w wodzie wodociągowej, która w odróżnieniu od recyrkulowanej wody technologicznej zawiera mało materii organicznej. Ponadto przechowywanie w warunkach chłodniczych próbek warzyw dezynfekowanych podchlorynem sodu prowadzi do zmiany ich barwy i obniżenia ogólnej akceptowalności [14,16,17]. ...
... Ruiz-Cruz i wsp. [17] wykazali wysoką skuteczność dezynfekcji korzeni marchwi tym związkiem przy każdym zastosowanym stężeniu (100, 250 i 500 mg/l). Uzyskano zmniejszenie liczby bakterii E. coli O157:H7 i Salmonella spp. ...
... Ruiz-Cruz i wsp. [17] uzyskali wyniki potwierdzające brak zależności pomiędzy wodą użytą do badań a skutecznością działania kwasu nadoctowego [17]. Redukcja liczby bakterii E. coli w marchwi wynosiła ok. ...
Article
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Microorganisms on surfaces of fruits and vegetables come not only from the natural environment but also from every stage of the food chain through which they have to pass (handling, packaging, and transportation). In the industrial processing plants, washing and disinfecting raw materials intended for direct consumption or production of unpasteurized juices is usually the only step in reducing the number of contaminating and pathogenic microorganisms. Particular attention should be paid to root vegetables because their edible parts have direct contact with the soil that is a habitat for many different groups of microorganisms. In the fruit and vegetable industry, sodium hypochlorite is the most commonly used disinfectant, which, despite its high efficiency, has many disadvantages: it causes corrosion of devices, may adversely affect the appearance, taste and smell of vegetables, and it contributes to the formation of dangerous trihalomethanes. In the paper, there are presented alternative to sodium hypochlorite substances used to disinfect root vegetables, mainly carrots, since those root vegetables are an important raw material in the Polish juice industry. The paper contains also a review of the literature relating to such compounds as acidified sodium chlorite, chlorine dioxide, hydrogen peroxide, peracetic acid, electrolyzed water, and ozone. There were depicted antimicrobial properties of disinfectants against yeasts, moulds, Gram-negative and Gram-positive bacteria as well as their disadvantages, dvantages, mechanism of action, and effect on the organoleptic characteristics and lifespan prolongation of vegetables. Among the disinfectant described, the electrolyzed water and acidified sodium chlorite are highlighted owing to their high efficacy and no negative impacts on vegetable tissues, environment, and consumer health.
... g L −1 on inactivation of pathogens, including E. coli O157:H7 and Salmonella spp. (Gonzalez et al. 2004;Park and Beuchat 1999;Ruiz-Cruz et al. 2007). However, a negative impact on organoleptic quality of red meat and shredded carrots occurred when ASC was used within the approved concentration range (Bosilevac et al. 2004). ...
... Conner (2001) and Caldwell et al. (2003) affirmed that ASC applied to inoculated fresh fruits and vegetables at 1.2 g L −1 for 1 min killed at least 99.9% of Salmonella serotypes, E. coli O157:H7, and L. monocytogenes on carrots, strawberries, tomatoes, cucumbers, lettuce, cantaloupe, and apples. Gonzalez et al. (2004), Inatsu et al. (2005), and Ruiz-Cruz et al. (2007) found a strong E. coli O157:H7 reduction, even under process water conditions, when using 0.5 and 1 g L −1 ASC on shredded carrots and Chinese cabbage. Allende et al. (2009) treated cut cilantro 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 . ...
Chapter
Fresh-cut produces, initially called minimally processed or lightly processed produces, are those that have been trimmed and/or peeled and/or cut into 100% usable product that is bagged or prepackaged. In particular, fresh-cut products attract consumers because they are fresh, nutritious, reasonably priced, and less time-consuming. As a consequence, a wide assortment of fresh-cut produces has been developed to meet consumer’s needs for “quick” and convenient products. With the busy lifestyles, consumer tends to use less time for preparing meals. Consumers prefer eating fruits and vegetables, and they prefer ready-to-eat products than preparing it themselves. As a result, the maintenance of the quality of fresh-cut produce has become more challenging to the food industry today.
... Results of the present study were consistent with that reported by Ruiz-Cruz et al 17 whereas microbial levels in carrot samples, collected from local wholesale market in México, ranged from 10 4 to 10 6 log CFU/g, but exceeded the recommended coliform levels by WHO and International Commission on Microbiological Specifications for Food standards, ranged from 10 to 10 2 log CFU/g 18 . Also, results of the present study were different than other studies in the southern United States that examined microbial load ranging from 2 to 3 log CFU/g on some tested items of fresh produce namely: arugula, parsley and spinach 9 . ...
Article
Full-text available
The consumption of fresh produce has increased significantly in the recent decades. So far, no data are available on the bacteriological burden and the prevalence of foodborne pathogens in fresh produce of Beheira Governorate. The aim of the present study was to evaluate some food-borne pathogens namely: Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7, in Beheira fresh produce. A total of 200 fresh produce samples were collected during a period of 11 month originating from different 21 agricultural fields, 13 marketplaces and 19 grocery stores in Beheira Governorate (Damanhour, El Mahmodya, Abo Homous and Kafr El Dawar) during April 2016 through March 2017. Out of 200 samples, 62 (31%) were contaminated with coliform. The highest coliform contaminated sources were that collected from grocery followed by market place then by agricultural field. The total mean log CFU/g ± SD for arugula, spinach and radish were the highest coliforms contaminated fresh produce among all tested fresh produce samples while cucumber was the lowest coliform contaminated fresh produce among all tested fresh produce samples. In the present study, 18 Salmonella, 4 L. monocytogenes and 104 fecal E. coli were detected (representing 9%, 2% and 52%, respectively). E.coli O157:H7 was not detected in all collected fresh produce samples. Proteomic identification of the isolated bacteria was made using MALDI TOF spectrometry. It was revealed that Salmonella isolates were considered as multidrug-resistant organisms. They showed resistance against some members of more than 3 antibiotic classes, cephalosporins (Cephradine, CE), tetracycline (Oxytetracycline, OT) and amphenicols (Chloramphenicol, C). ESBL was detected in all Salmonella isolates of the present work. L. monocytogenes isolates showed to be sensitive to all tested antibiotics.
... According to a study by Holvoet et al. (2014) most farmers could not guarantee the quality of water used in rinsing lettuce after harvest, this could be a crucial step in contributing additional contamination to the crop. During commercial production of fresh fruit and vegetables, water used for cleaning is often reused and recycled and this can result in cross contamination (Ruiz-Cruz et al., 2007;Luo et al., 2011). It is also important to consider the possibility of delicate lettuce plants becoming physically damaged through commercial processing. ...
Article
Antibiotic resistant bacteria (ARB) have been found on fresh fruit and vegetables globally. These types of ARB infections are spreading rapidly and are a major human health threat. A quantitative human exposure assessment model was created using scenario analysis to investigate the potential human exposure to antibiotic resistant Escherichia coli (AR-E. coli) through the consumption of lettuce irrigated with surface water. Scientific literature and site specific data were collected to model each process from farm to fork to calculate the concentration of AR-E. coli on the lettuce at the point of human consumption. The processes examined were the adhesion, colonisation and viability of bacteria on the lettuce; the effect of different post-harvest cleaning processes; the effect of consuming the lettuce before, on or after the expiry date; and the effect of the consumer washing the lettuce. The results show the mean human exposure levels ranged between 1.00 × 10⁻² and 1.35 × 10⁶ colony forming units (CFU) of AR-E. coli per 100 g of surface water irrigated lettuce for the different scenarios investigated. The mean probability of illness from consuming 100 g of lettuce contaminated with potential pathogenic antibiotic-sensitive E. coli was between 1.46 × 10⁻⁹ to 1.88 × 10⁻². A back calculation revealed that in order for the EC No 1441/2007 regulation to be exceeded (≥1000 CFU/g of E. coli on lettuce at the manufacturing stage), the mean contamination levels required in the irrigation water would need to be 2.7, 3.1 or 4.8 log CFU/ml using the post-harvest treatments of washing with water, rapid cooling with water and washing with a chlorine solution respectively. The information generated from this model could help to set guidelines for producers on maximum permissible AR-E. coli contamination levels in irrigation water and provides recommendations on the best post-harvest treatment to use.
... Results of the present study were consistent with that reported by Ruiz-Cruz et al 17 whereas microbial levels in carrot samples, collected from local wholesale market in México, ranged from 10 4 to 10 6 log CFU/g, but exceeded the recommended coliform levels by WHO and International Commission on Microbiological Specifications for Food standards, ranged from 10 to 10 2 log CFU/g 18 . Also, results of the present study were different than other studies in the southern United States that examined microbial load ranging from 2 to 3 log CFU/g on some tested items of fresh produce namely: arugula, parsley and spinach 9 . ...
Data
Full-text available
The consumption of fresh produce has increased significantly in the recent decades. So far, no data are available on the bacteriological burden and the prevalence of foodborne pathogens in fresh produce of Beheira Governorate. The aim of the present study was to evaluate some food-borne pathogens namely: Salmonella, Listeria monocytogenes, and Escherichia coli O157:H7, in Beheira fresh produce. A total of 200 fresh produce samples were collected during a period of 11 month originating from different 21 agricultural fields, 13 marketplaces and 19 grocery stores in Beheira Governorate (Damanhour, El Mahmodya, Abo Homous and Kafr El Dawar) during April 2016 through March 2017. Out of 200 samples, 62 (31%) were contaminated with coliform. The highest coliform contaminated sources were that collected from grocery followed by market place then by agricultural field. The total mean log CFU/g ± SD for arugula, spinach and radish were the highest coliforms contaminated fresh produce among all tested fresh produce samples while cucumber was the lowest coliform contaminated fresh produce among all tested fresh produce samples. In the present study, 18 Salmonella, 4 L. monocytogenes and 104 fecal E. coli were detected (representing 9%, 2% and 52%, respectively). E.coli O157:H7 was not detected in all collected fresh produce samples. Proteomic identification of the isolated bacteria was made using MALDI TOF spectrometry. It was revealed that Salmonella isolates were considered as multidrug-resistant organisms. They showed resistance against some members of more than 3 antibiotic classes, cephalosporins (Cephradine, CE), tetracycline (Oxytetracycline, OT) and amphenicols (Chloramphenicol, C). ESBL was detected in all Salmonella isolates of the present work. L. monocytogenes isolates showed to be sensitive to all tested antibiotics.
... With the aim of complying with GMP for fresh-cut products (including sliced fresh potato), NaClO was exclusively used as antimicrobial agent because of potato susceptibility to Bacillus and Clostridium contaminations, which can survive and grow in cooked potato products (Thomas et al., 2002). Blanching is not a sterilisation procedure and, thus, a two-step washing with NaClO was performed in the concentration range reported by Ruiz-Cruz et al. (2007). ...
Article
The worldwide potato production is considered the fourth‐most important food sector due to the increasing use of potatoes as raw materials for high‐convenience food. Enzymatic browning, due to polyphenol oxidase (PPO), is related to unacceptability by consumer. Among antibrowning agents, thermal treatments are viable alternatives. In this study, the efficacy of hot‐water and steam blanching at 80–90 °C of potato slices (1‐cm thick) was evaluated in terms of colour changes as well as PPO inactivation kinetics, substrate specificity and transition state parameters. In general, all treatments [1] bleached the slices, [2] inactivated PPO and [3] reduced its kinetic efficiency. Results from thermal inactivation kinetics promoted hot‐water blanching at 90 °C for approx. 2 min as the fastest treatment to obtain enzymatic‐stable potato slices. Moreover, steam blanching required more energy (53.93 ± 1.24 kJ mol⁻¹) than hot‐water treatment (41.41 ± 4.51 kJ mol⁻¹) to reach the transition state and then to unfold the PPO enzyme.
... According to a study by Holvoet et al. (2014) most farmers could not guarantee the quality of water used in rinsing lettuce after harvest, this could be a crucial step in contributing additional contamination to the crop. During commercial production of fresh fruit and vegetables, water used for cleaning is often reused and recycled and this can result in cross contamination (Ruiz-Cruz et al., 2007;Luo et al., 2011). It is also important to consider the possibility of delicate lettuce plants becoming physically damaged through commercial processing. ...
Article
It is important that bathing water sites are free as possible from antibiotic resistant bacteria (ARB) to prevent the spread of difficult to treat infections throughout the population. This study examines the possible human exposure to antibiotic resistant Escherichia coli (AR-E. coli) through recreational activities at two different bathing water sites located near wastewater treatment plants (WWTPs). A quantitative risk assessment model was created to model the pathway of the AR-E. coli from the WWTPs effluent water through to the bathing water sites. Both sampling data and data from scientific literature were used. The main steps considered for the model were: the dilution and decay of the AR-E. coli from the WWTPs effluent water into the river; the dilution of the river into the bathing water sites and the human exposure to AR-E. coli through recreational activities at the bathing water sites (as a result of water ingestion). The results show the mean predicted human exposure levels ranged between 0.45 and 345.09 cfu/100 ml. A back calculation method determined that in accordance with the European Bathing Water Directive (2006/7/EC) (BWD) to be considered “poor” water quality, the concentration of AR-E. coli in WWTP effluent water would need to exceed 2.45 log cfu/ml at site 1 and exceed 2.71 log cfu/ml at site 2. This study provides valuable information for regulatory bodies and policy makers on the possible human exposure levels to AR-E. coli and the maximum permissible concentrations in WWTP effluent water to ensure compliance with relevant bathing water legislation.
... Studies have been carried out on food matrices such as iceberg and romaine lettuce (Beuchat and Scouten, 2004;Rodgers et al., 2004;Bachelli et al., 2013), fresh-cut jalapeño pepper (Ruiz-Cruz et al., 2010), potato (Hilgren and Salverda, 2000), grated carrot (Vandekinderen et al., 2009b), fresh-cut carrots (Ruiz-Cruz et al., 2007a), strawberries (Van de Velde et al., 2015, spinach (Spinacia oleracea) (Neal et al., 2012), watermelon seeds (Hopkins et al., 2003), green coconuts (Cocos nucifera L.) (Walter et al., 2009), whole apples (Wisniewsky et al., 2000;Rodgers et al., 2004;Kim et al., 2018), fresh-cut white cabbage (Vandekinderen et al., 2009a), fresh-cut melon cubes (Botondi et al., 2016), cantaloupes (Cucumis melo L.) (Rodgers et al., 2004;Park and Beuchat, 1999;Bastos et al., 2005;Fan et al., 2009), honeydew melons, and asparagus (Park and Beuchat, 1999), where PA has been shown to have an efficient antimicrobial effect against pathogenic microorganisms. ...
Chapter
Full-text available
Chemical sanitizers are important to the quality and safety of minimally processed food products, such as fresh and fresh-cut fruits and vegetables. While chlorine remains the most widely used chemical sanitizer in the fresh produce industry, other equally effective and cost-efficient alternatives that are more environmentally and worker friendly are needed. Peracetic acid (PA), an equilibrium mixture of hydrogen peroxide and acetic acid, has been approved by the US Food and Drug Administration (FDA) to sanitize food contact surfaces of equipment and direct washing of fruits and vegetables. The PA shows potential as an alternative sanitizer because it has strong oxidizing capabilities, does not produce harmful by-products or leave behind residues, and is accepted for use in organic production. The use of and research on PA in postharvest disinfection of fruits and vegetables is presented here, highlighting its mechanism, composition and efficacy, potential toxicity and sensory effect, along with its regulatory status.
... Hilgren and Sailverda (2000) showed that washing cabbage and celery with 80 ppm PA for 30 s reduced aerobic count by 0.84 and 1.07 log CFU/g, respectively. Ruiz-Cruz et al. (2007) showed that washing shredded carrots with 40 ppm PA for 2 min reduced Salmonella and E. coli O157:H7 populations by 2.1 and 1.24 log CFU/g, respectively. Furthermore, Nascimento et al. (2003) reported that 80 ppm AA (Tsunami 100 ® ) for 15 min reduced aerobic mesophilic and total coliform on lettuce by 1.85 and 1.44 log CFU/g, respectively. ...
Article
Enterobacteriaceae family can contaminate fresh produce at any stage of production either at pre-harvest or post-harvest stages. The objectives of the current study were to i) identify Enterobacteriaceae species on iceberg lettuce, ii) compare the decontamination efficiency of water, sodium hypochlorite (free chlorine 200 ppm), peroxyacetic acid (PA 80 ppm; Kenocid 2100®) or their combinations and ionizing radiation against Enterobacteriaceae on shredded iceberg lettuce and iii) determine the survival of Enterobacteriaceae post-treatment storage of shredded iceberg lettuce at 4, 10 and 25 °C, for up to 7 days. Klebsiella pneumonia spp. pneumonia, Enterobacter cloacae, Klebsiella oxytoca, Pantoea spp., Leclercia adecarboxylata and Kluyvera ascorbate were identified on iceberg lettuce. No significant difference (P ≥ 0.05) among Enterobacteriaceae survival after washing with water or sanitizing with sodium hypochlorite or Kenocid 2100® (reduction ≤ 0.6 log CFU/g) were found. Combined sanitizer treatments were more effective against Enterobacteriaceae than single washing/sanitizing treatments. Sanitization of iceberg lettuce with combined washing/sanitizing treatments reduced Enterobacteriaceae by 0.85–2.24 CFU/g. Post-treatment growth of Enterobacteriaceae during storage on samples sanitized with sodium hypochlorite and Kenocid 2100® was more than on samples washed with water. The D10-value of Enterobacteriaceae on shredded iceberg lettuce was 0.21 KGy. The reduction of Enterobacteriaceae populations on iceberg after gamma radiation (0.6 KGy) was 3 log CFU/g, however, Enterobacteriaceae counts increased post-irradiation storage by 4–5 log CFU/g. Therefore, washing shredded iceberg lettuce with combined sanitizing treatment (sodium hypochlorite/sodium hypochlorite, sodium hypochlorite/Kenocid 2100®, or Kenocid 2100®/Kenocid 2100®) for total time of 6 min or exposing it to gamma irradiation (0.6 KGy) can decrease the risk of Enterobacteriaceae (reduction ≥ 2 log). Post-washing storage of sliced iceberg lettuce (4, 10, 25 °C) could increase the risk of Enterobacteriaceae as their counts increased during storage even at low temperatures.
... Chlorine exerts its germicidal property by penetrating into the bacterial cell wall; it interferes with sulfhydril containing enzymes of glucose metabolism thereby leading to death of bacteria (Banwart, 1979). Similarly per acetic acid also has shown better effect in reducing the bacterial load on food material and also has effective antimicrobial activity in presence of organic matter compared to chlorine (Cruz et al., 2007). Per acetic acid is most commonly used in food processing and handling, sanitizer for food contact surfaces and as a disinfectant for fruits, vegetables, meats, and eggs. ...
Article
Full-text available
Salmonellosis is one of the major leading foodborne zoonotic diseases reportedworldwide, poultry and poultry products including table eggs were reported as the most important source for foodborne outbreaks in humans. The present study was designed to determine and compare the occurrence of Salmonellaserovarsby cultural andmolecular (PCR) methodsin processed, unprocessed and desi table eggs available in the markets, resistance pattern of isolates for commonly used antibiotics and decontamination of table eggs using chlorine and peracetic acid. The results of present study revealed that occurrence of Sal. Enteric was found to be 5.95 and 9.52 per cent by cultural and PCR method, respectively.Among the isolates obtained, 3.57 per cent was found to beS.enteritidisand 2.38 per cent of was S. typhimurium serotypes. The occurrence of S.entericawas found to be 2.08, 8.33 and 16.67 per cent in processed, unprocessed and desi table eggs, respectively. The MAR indices forall five isolatesSalmonella entericawas 0.2.Considering the reduction of TVC and Salmonella counts from the table egg surface after sanitation, 100 ppm of peracetic acid (PAA) as a sanitizer was comparatively effective than 200 ppm of chlorine (CL).Higher occurrence of Salmonellaspecies in the egg is of great public health concern. The study further reinforces the necessity of improving the table eggs before it reaches the consumer
... Por ejemplo, se ha mostrado que el AP fue efectivo para controlar E. coli, Salmonella spp. y L. monocytogenes en melones, espárragos, lechuga, fresas, zanahorias y manzanas MPF (Rodgers et al., 2004;Ruiz-Cruz et al., 2007;Abadias et al., 2011). ...
Article
The elaboration of fresh-cut vegetables needs a disinfection step to reduce the growth of spoilage and pathogenic microorganisms.In general, this requires the addition of sanitizers such as chlorine or hypochlorites. However, due to the fact that chlorinereacts with other organic compounds, leading to the formation of halogenated by-products that are harmful to health, such astrihalomethanes and chloramines, concerns over the toxicity of these derivatives have led to the current interest of usingalternative and environmentally-friendlier products. The concern over these new sanitizers is not only due to their inactivationcapabilities against a wide range of pathogenic and spoilage microorganisms, but at the same time, over their ability to maintainthe sensory quality of the product. Currently, there are a number of sustainable and emerging disinfection techniques that canreplace chlorine, providing other benefits, such as ozone (O3), electrolyzed water (AE), ionizing or non-ionizing radiation,natural antimicrobials, bacteriocins, heat treatments, certain chemical agents as peroxyacetic acid and many others. In thispaper, we review the effectiveness of O3, AE and peroxyacetic acid. All of them have proven their microbicidal efficacy againstpathogenic bacteria in fresh-cut vegetables.
... (up to 99.9%) from a variety of fruits and vegetables including strawberries, carrots, tomato, lettuce, cucumbers, cantaloupes, and apples. Considerable reductions in the counts of E. coli were observed when 0.5 to 1 g/L concentrations of ASC were used to treat fresh cut carrots, cilantro, and Chinese cabbage (Allende et al., 2009;Gonzalez, Luo, Ruiz-Cruz, & McEvoy, 2004;Inatsu et al., 2005; Ruiz-Cruz, Acedo-Félix, Díaz-Cinco, Islas-Osuna, & González-Aguilar, 2007). ASC at 0.1 and 0.2 g/L concentrations successfully reduced E. coli and Salmonella populations from strawberries and were found to have a better bactericidal effect than chlorine dioxide gas. ...
Article
Fresh fruits and vegetables are a rich source of micronutrients. However, many foodborne illnesses have been linked to the consumption of fresh fruits and vegetables as they are reported to harbor contaminants such as microorganisms and pesticides. Recently reported foodborne outbreaks have been linked to a diverse group of fruits and vegetables due to the presence of various pathogens including Salmonella, Escherichia coli, and Listeria monocytogenes. Also, the increased use of pesticides has resulted in the deposition of chemical residues on the surface of fruits and vegetables, which has led to the adverse health conditions such as cancer, birth defects, and neurodevelopmental disorders. Fresh commodities are subjected to various treatments to prevent or minimize these outbreaks, and the main targets of such treatments have been the elimination of pathogens and degradation of toxic chemical residues. Here, we have discussed various decontamination methods including simple household washing, chemical treatments, and modern technologies with their mode of action for microbial and pesticide removal. The simple household processes are not very effective in the removal of pathogenic organisms and pesticides. The use of modern techniques like cold plasma, ozone, high hydrostatic pressure, and so on, showed better efficacy in the removal of microorganisms and pesticides. However, their industrial use is limited considering high installation and maintenance cost. In this review, we suggest combined methods based on their mode of decontamination and suitability for a selected fruit or vegetable for effective decontamination of microbes and pesticide together to reduce the treatment cost and enhance food safety.
... The Food and Drug Administration of USA (FDA) approves chlorine for use as an indirect food additive (FDA 2005). PAA is better in reducing the bacterial load on food material and also has effective antimicrobial activity in the presence of organic matter compared to chlorine (Cruz Ruiz et al. 2007), but the efficacy of PAA as a sanitiser for table eggs has not been widely reported. ...
Article
1. Escherichia coli is one of the most common facultative anaerobic species present in the gastrointestinal tract of animals and human beings. Usually they occur as commensals, but some serotypes can cause significant illnesses in humans as well as mammals and birds. 2. The occurrence of E. coli in different categories of table eggs collected from markets was evaluated. Isolates were analysed for the presence of virulence genes, antibiotic susceptibility pattern and efficacy of peracetic acid and chlorine for the purpose of decontaminating table eggs. 3. Significant differences were observed in the occurrence of E. coli between different groups viz. processed (cleaned, washed, sanitised and packed eggs), unprocessed (un-cleaned, un-sanitised and loose eggs) and free range (eggs obtained from backyard poultry) table eggs. Overall, E. coli occurred in table eggs at 28.6% with 22.9%, 29.2% and 50.0% occurrence in processed, unprocessed and free range table eggs, respectively. 4. A total of 24 isolates of E. coli were obtained and screened for virulence genes viz. STH, SLT1/2, and INVE genes. Of the 24 isolates recovered, 10 typeable isolates belonged to O141, O119, O9, O120 and O101 serotypes, while the remaining 14 were untypeable. Antibiograms of the isolates showed multiple antimicrobial resistance (MAR) index in the range of 0.13 to 0.40. 5. Peracetic acid (PAA) and chlorine (CL) were studied for their sanitisation efficacy; concentrations of 100 mg/kg of PAA and 200 mg/kg of CL completely inactivated E. coli over the egg surface and also resulted in 2.58 and 2.38 log reduction in total viable counts (TVC), respectively. 6. The presence of virulence-associated shiga-like toxin (SLT1/2) and invasion E (INVE) genes and antimicrobial resistance among the emerging serotypes of pathogenic E. coli isolated from table eggs has public health implications. It underscores the need to implement better management practices across the production systems and marketing channels to produce E. coli-free wholesome eggs for consumers.
... The efficiency of the sanitizers may be limited depending upon the characteristics of the evaluated surface (Ruíz-Cruz, F elix, Cinco, Islas-Osuna, & Gonz alez-Aguilar, 2007). Harvesting and postharvesting of fruits and vegetables can cause tissue injuries and promote the growth of pathogenic bacteria. ...
Article
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Sanitization is a critical step for the reduction of microbial contaminants in fruits and vegetables in an effort to lessen the occurrence of foodborne diseases. The efficiency of different chemical compounds, either individually or combined with ultrasound treatment, in decontaminating fresh arugulas was evaluated here. The main physicochemical properties and the natural microbiota of arugulas were evaluated after sanitization for 5 min at 25 °C. The synergistic effect of ultrasound and sodium hypochlorite led to the best outcome. Ultrasound treatment improved the bactericidal effect of sodium hypochlorite (100 mg/L), leading to a reduction of 1.46 log cycles in relation to the non-sanitized samples, whereas sodium hypochlorite itself provided a 0.85 log cycle reduction. This synergism is due to the ability of ultrasound-induced cavitation to form oxidizing free radicals (e.g., ·OH and ·Cl), in addition to its mechanical energy input that facilitates the permeation of hypochlorous acid molecules into microbial cells. It is noteworthy that this mechanical action also favors the removal of microbial biofilms and cell disintegration. The residual chlorine content was lower than that recommended by the current legislation for public water supply. The combined action did not significantly alter the physicochemical and colorimetric properties of the arugulas. Therefore, this sanitization protocol denotes a promising alternative for the decontamination of fruits and vegetables in the food industry and in food processing facilities. Currently, there has been an increase in the demand for fresh food as well as an increase in the number of food outbreaks involving these products. In this context, to reduce microbial contamination, this research presents an alternative sanitization method that can be easily used in food processing units for decontamination of vegetables, increasing the microbiological safety of the final product to the consumer.
... However, the preservation of fresh-cut apples is difficult work, because the fresh-cut fruit undergoes rapid deteriorative processes which can promote the decay of the fruit. Meanwhile, because of enzymatic browning, tissue softening, and the microbial growth of the sliced fruits, they generally have a short shelf-life [3]. In order to extend the shelf-life of the fresh-cut apple, a range of treatments have been applied, such as the use of natural browning inhibitors [4], salt and chemical treatments [5], coating agents and reduced oxygen atmospheres [6,7]. ...
Article
Full-text available
A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (ε) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce.
... However, pathogenic microbes on the surface of carrots after washing and bacterial biofilm formation on the surface may pose a food safety risk [4]. Non-thermal treatments including gamma ray exposure [5], UV-C exposure and immersion in ozone water [6], electrolyzed water [7], and aqueous chlorine [8] have been applied to freshly cut carrots. Among those treatments, chlorine is the most commonly used sanitizer for reducing pathogens on fresh produce. ...
Article
This study aimed to evaluate the effectiveness of aerosolized chlorine dioxide (ClO2) in reducing Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on washed carrots at various time durations and conditions. Populations of the bacteria on carrots were reduced by 1.5, 1.5, and 1.3 log CFU/g, respectively, in each inoculum after exposure to 300 ppm of aerosolized ClO2 for 30 min. Populations were further reduced by 2.4, 2.3, and 2.1 log CFU/g, respectively, at 400 ppm, showing a positive correlation between the concentrations of ClO2 and microbial control. The D-value was 13, 14, and 15 min for E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. ClO2 residues were 1 ppm or less in all treated carrots, showing no appearance or discoloration defects. As a result, effectiveness of aerosolized ClO2 in reducing bacterial pathogens and maintaining the quality of fresh carrots is signifying the prospects of aqueous ClO2 as a non-thermal disinfectant.
... Findings in this study clearly showed that the conventional washing treatment by using tap water was insufficient to achieve a high log reduction of foodborne pathogens. Similar studies by Park andBeuchat (1999), Saul, Evelia, Martha, Maria, andGustavo (2007), and Uyttendaele, Neyts, Vanderswalmen, Notebaert, and Debevere (2004) also found that washing vegetables by using tap water only was not effective in reducing pathogens on inoculated vegetables. Also, Chai et al. (2008) reported that soaking fresh vegetables in a bucket of tap water achieved only a 0.4-log reduction of Campylobacter jejuni (in MPN per gram). ...
Article
Epidemiological data indicates that a large number of foodborne illnesses are attributed to cross-contamination during food preparation in the domestic kitchen. The objectives of this study were to evaluate the efficiency of household washing practices in removing Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Enteritidis on artificially contaminated lettuce and to determine the transfer rate of these three foodborne pathogens from contaminated lettuce to wash water, tomato, cabbage, and cutting boards during washing and cutting processes. Washing under the running tap water with scrubbing for 60 s was the most effective method in reducing pathogen populations by 1.86 to 2.60 log10 CFU/g. Also, final rinsing and scrubbing practices were found to enhance the efficiency of washing treatment. In this study, the transfer rates of S. Enteritidis, E. coli O157:H7, and L. monocytogenes from cutting board to cabbage and tomato via cutting process (17.5 to 31.7%) were higher (P<0.05) than from wash water to cabbage and tomato (0.8 to 23.0%) during washing treatment. Overall, our findings suggest that wash water and cutting board can be potential vehicles in the dissemination of foodborne pathogens. Therefore, there is a need to promote consumer awareness for proper handling practices in the kitchen to minimise the risk of foodborne infection.
... reductions of 2-3 log CFU g ?1 were reported in apples and melons treated with 70 ppm of PAA [9,10]. Similarly, E. coli O157:H7, Salmonella spp., and Listeria monocytogenes inoculated on FC carrot shreds were reduced after PAA washing at 40 ppm for 2 min [11]. Mesophilic and psychrotrophic loads of FC Galia melon were reduced by 1 and 2 log CFU g ?1 , respectively, using PAA (68 ppm) [12]. ...
Chapter
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The current high demand of minimally processed or fresh-cut fruit and vegetables results from the consumer’s desire for healthy, convenient, fresh, and ready-to-eat plant food-derived commodities. Fresh-cut fruits and vegetables are usually packaged under active- or passive-modified atmosphere packaging, while its shelf life must be under refrigerated conditions. The most important goal to preserve quality and safety focuses on releasing the microbial spoilage flora, since every unit operation involved will influence the final load. Sanitation in the washing step is the only unit operation able to reduce microbial load throughout the production chain. Chlorine is widely used as an efficient sanitation agent, but some disadvantages force to find eco-friendly emerging alternatives. It is necessary to deal with aspects related to sustainability because it could positively contribute to the net carbon balance besides reducing its use. Several innovative techniques seem to reach that target. However, industrial changes for replacing conventional techniques request a fine knowledge of the benefits and restrictions as well as a practical outlook. This chapter reviews the principles of emerging eco-friendly techniques for preserving quality and safety of fresh-cut products in order to meet the expected market’s demand.
... Thus, a number of food scientists have tried to find alternatives to chlorine. The bactericidal efficacy of commercially available food sanitizers, including peroxyacetic acid and ASC, has been frequently examined.Ruiz-Cruz, Acedo-Félix, Díaz-Cinco, Islas-Osuna, and Gonz alez-Aguilar (2007)reported that ASC was more effective than peroxyacetic acid againstPeroxyacetic acid 40 ppm, 1e2 min EHEC (O157:H7) Shredded carrots 1.2 log CFU/g RuizCruz et al. (2007)80 ppm, 15 s EHEC (O157:H7) Spinach 1.1 log CFU/gNeal et al. (2012)80 ppm, 10e25 C, 5 min EHEC (O157:H7) Rock salad leaves 0.3e1.2 log CFU/g AlNabulsi et al. (2014)70 ppm, 90e180 s EHEC (O157:H7) Mung bean sprouts 2.3 log CFU/gNeoHydrosols of Lamiaceae spices mixture, 20 min EHEC (O157:H7) Cucumber >6 log CFU/gSagdic et al. (2013)1.3 ...
Chapter
This review examined scientific reports and articles published from 2007 to 2016 regarding the major environmental sources of pathogenic Escherichia coli and the routes by which they enter the human gastrointestinal tract. The literature describes novel techniques used to combat pathogenic E. coli transmitted to humans from livestock and agricultural products, food-contact surfaces in processing environments, and food products themselves. Although prevention before contamination is always the best “intervention,” many studies aim to identify novel chemical, physical, and biological techniques that inactivate or eliminate pathogenic E. coli cells from breeding livestock, growing crops, and manufactured food products. Such intervention strategies target each stage of the food chain from the perspective of “Farm to Table food safety” and aim to manage major reservoirs of pathogenic E. coli throughout the entire process. Issues related to, and recent trends in, food production must address not only the safety of the food itself but also the safety of those who consume it. Thus, research aims to discover new “natural” antimicrobial agents and to develop “multiple hurdle technology” or other novel technologies that preserve food quality. In addition, this review examines the practical application of recent technologies from the perspective of product quality and safety. It provides comprehensive insight into intervention measures used to ensure food safety, specifically those aimed at pathogenic E. coli.
... The possible reasons for such wider application despite developments in alternative less toxic disinfection processes are: (a) ready availability, (b) easy application, (c) less hassle, and (d) cost effectiveness. However, the inadequate efficiency due to adaptation of pathogens to such chemical agents (Ruiz-Cruz et al., 2007) have necessitated the search for other new strategies. In this regard a very simple solution was evinced where, sonic waves were projected into a cleaning solution, which resulted in cavitation and carryout the microbial inactivation for surface decontamination. ...
Article
Full-text available
Ultrasonic is one of the promising technological innovation to modify structure, inactivate enzymes and/or neutralize microorganisms in food products for enhancement of their quality and safety. Apart from pasteurization, sanitation, disinfection and cleaning procedures, in the area of food microbiology, ultrasound can facilitate recovery of microorganisms and their identification through cell lysis or detachment of microbe from food surface. Hence, study of effect of sound waves on microbial cells in suspended condition and food matrices has opened a new horizon of its application in the area of food microbiology. Use of ultrasound in microbial analysis is already in practice and expanding, but the physics of interaction of acoustic waves with microbial cells in presence of actual food matrices need further attention. Ultrasonic reactor (UR) design needs interdisciplinary approach to further exploit the promise of ultra sound in food microbiology. Substantial demand in recent years for bench-top ultrasound reactors for cleaning of food contact surfaces in common households has increased. This review deals with the state of art of the ultrasound technology, process development, and further scope of the technology specific for its applications in cleaning and sanitization, microbial inactivation and in microbiological analysis in food processing industries.
... Antimicrobial treatment is applied extensively in the food industry due to mounting concerns over food microbial contamination and human infection risk Vandekinderen et al., 2009). Different washing agents have been studied to determine their efficacy in the inactivation of pathogenic bacteria on fruits and vegetables (Alvarado-Casillas et al., 2009;Ruiz-Cruz et al., 2007). Although, chlorine which is still considered the most commonly used sanitizer due to its simple use, cost effectiveness and its efficacy, future regulatory restrictions will require the development of functional alternatives. ...
Article
Full-text available
Due to increasing demand of fresh-cut fruits and vegetables or minimally processed foods that are convenient with fewer preservatives, high nutritive value, and fresh sensory attributes, the fresh-cut produce industry is one of the fastest growing food industries worldwide. This study was conducted to determine the antimicrobial efficacy of calcium ascorbate and calcium lactate on fresh-cut pineapple and evaluate the physicochemical and sensory qualities of the treated and untreated produce. Freshly harvested ripe 'Queen' pineapple fruits (25-60% of the eyes yellow) were obtained from a local plantation, peeled, and sliced as commercially practiced. Calcium ascorbate and calcium lactate were applied at 1.5-2.5% as 2-min dip. Control treatments included 150 ppm chlorine and distilled water as 2-min dip. The product samples were packed in sterile resealable 50 μm-thick polyethylene bag and stored at 7-10 °C for 5 days. Calcium ascorbate and calcium lactate were effective in reducing aerobic and coliform bacteria as well as yeasts and molds at 2.5% concentration. The antimicrobial activities of these organic salts were comparable to chlorine after 3 hours from treatment but were much better than chlorine after 5 days of storage. Meanwhile, the physicochemical properties (color evaluation, titratable acidity, and pH) and sensory attributes (color, aroma, taste, texture, and general acceptability) of fresh-cut pineapple after 5 days of cold storage were not adversely affected using calcium ascorbate.
... 0.1 ml sample from each dilution was taken and spread plated into prepared media plates (PCA and PDA). The plates were then kept in incubator at 25°C [19] for fungal count and 37°C [20] for bacterial count. Colonies were counted after 48 h of incubation. ...
Article
Aims: To reduce the microbial load on cut-carrot surface using 390 nm Light Emiting Diode ( LED) illumination Place and Duration of Study: Agro-Produce Processing Division, ICAR Central Institute of Agricultural Engineering, India between August, 2017 to November, 2019 Methodology: Samples were collected from local market from India and LED treatment was given to samples and microbial analysis was conducted using spread plate method. Results: The effect of 390 nm LEDs on cut-carrot surface has been evaluated in this study. The effect of dosage was found significant (p<0.05) for reducing bacterial and fungal load. Significant bacterial and fungal reduction was observed from 20 min of treatment till 3 h. Maximum inactivation of 28.4 % of bacteria and 24.1 % of fungus were detected at 3 h of exposure. These results demonstrated the potential of 390 nm LEDs as surface decontamination technology for cut-fruits and vegetables. Conclusion: 390 nm LED illumination can be a suitable and eco-friendly novel technology for surface decontamination of cut fruits and vegetables in the food industry.
... Melon-associated L. monocytogenes outbreaks have also been reported in previous years [7,8]. In addition, the prevalence of L. monocytogenes in fresh produce including lettuce [9], mushrooms [10], cabbage [11], carrots [12,13], radishes [14,15], corn [16], parsley [17], strawberries [10], watercress [18], celery [19], red peppers [20], cucumbers [21], and several other salad vegetables [22] has been reported through microbiological risk assessment surveys from various countries. ...
Article
Full-text available
Contamination by Listeria monocytogenes in packaged produce is a major concern. The purpose of this study was to find natural and affordable sanitizers to reduce L. monocytogenes contamination in agricultural products. Organic acids, ultraviolet-C (UV-C), and ethanol were analyzed either alone or in combination to assess their ability to reduce L. monocytogenes population in radish, oriental melon, and carrot samples. In radish samples, 3% malic acid combined with UV-C at a dosage of 144 mj/cm2 significantly reduced (>4 log CFU/g) the population of L. monocytogenes (1.44 ± 0.5) compared to the control sample (5.14 ± 0.09). In the case of the melon samples, exposure to UV-C at a dosage of 144 mj/cm2 combined with 3% lactic acid (2.73 ± 0.75) or 50% ethanol (2.30 ± 0.01) was effective against L. monocytogenes compared to the control sample (5.10 ± 0.19). In carrot samples, 3% lactic acid combined with 144 mj/cm2 dosage UV-C reduced L. monocytogenes population (4.48 ± 0.25) more than in the control sample (5.85 ± 0.08). These results reveal that sanitizers that are effective for one crop are less effective for another crop indicating that effective prevention methods should be customized for each crop to prevent pathogen cross contamination during postharvest washing.
... Dip inoculation was applied to simulate the immersion process which is a suspected point of contamination in food production (Ruiz--Cruz et al., 2007). Specifically, each pea sprouts sample (10 g) was submerged in the 100 mL of prepared E. coli suspension for 10 min, followed by air-dried for 30 min in a laminar flow biosafety cabinet (Chen et al., 2019Liu, Tan, et al., 2017;Zhao, Zhao, Phey, & Yang, 2019). ...
Article
The antimicrobial effects of low concentration electrolysed water (LcEW) on common foodborne pathogens have been well documented; however, the effects on six emerging Escherichia coli serotypes (the “big six”) remained unknown. Using pea sprouts as the food matrix, this in vivo study examined the sanitising efficacy of a 10-min LcEW treatment against eight E. coli strains (non-pathogenic E. coli ATCC 25922, pathogenic E. coli O26:H11, O45:H2, O103:H11, O111, O121:H19, O145 and O157:H7). The metabolic responses of the strains were further analysed using nuclear magnetic resonance (NMR) spectroscopy. An overall negative correlation between the resistance to LcEW and the magnitude of metabolic variation was observed. The metabolic status and pathways of the most resistant O103:H11 and O45:H2 strains were the least affected. The O26:H11 and O145 strains which demonstrated the highest sensitivity to LcEW had an array of metabolites depleted and had multiple pathways involved in amino acid metabolism, energy metabolism as well as osmotic and oxidative protection perturbed. Distinctive metabolic responses were detected in ATCC 25922, suggesting that alternative stress defence mechanisms may be present in the non-pathogenic E. coli strain. Amongst the pathogenic strains, the most unique metabolic responses were illustrated by O121:H19. Overall, the study showed that the NMR-based metabolomics is promising in elucidating the metabolic changes of various E. coli strains in pea sprouts during an antimicrobial process. It also provides clue for controlling “big six” contamination in fresh produce.
... Washing with chemical sanitizers, such as chlorine, is the most commonly postharvest method for minimizing cross-contamination and risk of pathogens on fresh produce. However, washing with sanitizers has limited effectiveness in alleviating the problem of pathogen contamination in produce (Balaguero et al., 2015;Gil et al., 2009;Ruiz-Cruz et al., 2007;Singh et al., 2002). Other technologies across a range of methods have been identified and evaluated. ...
Article
Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by <0.6 log CFU/fruit on both the smooth surface and the stem scar area, and aerosolized hydrogen peroxide alone reduced the populations by up to 2.1 log CFU/fruit on the smooth surface and 0.8 log CFU/fruit on stem scar area. However, the combination treatments reduced the populations by up to 5.2 log CFU/fruit on smooth surface and 4.2 log CFU/fruit on the stem scar. Overall, our results demonstrate that gaseous ozone and aerosolized hydrogen peroxide have synergistic effects on the reduction of Salmonella populations on tomatoes.
... Others studies demonstrated the possibility of growth of Salmonella spp. and Listeria monocytogenes on carrots [19]. The fungal strains of Alternaria, Rhizopus, Aspergillus, Stemphylium and Botrytis were also found to contaminate carrots [20,21]. ...
Article
Full-text available
The antimicrobial activity of natural antimicrobials (fruit extracts, essential oils and derivates), was assessed against six bacteria species (E. coli O157:H7, L. monocytogenes, S. Typhimurium, B. subtilis, E. faecium and S. aureus), two molds (A. flavus and P. chrysogenum) and a yeast (C. albicans) using disk diffusion method. Then, the antimicrobial compounds having high inhibitory capacity were evaluated for the determination of their minimum inhibitory, bactericidal and fungicidal concentration (MIC, MBC and MFC respectively). Total phenols and flavonoids content, radical scavenging activity and ferric reducing antioxidant power of selected compounds were also evaluated. Based on in vitro assays, five antimicrobial compounds were selected for their lowest effective concentration. Results showed that, most of these antimicrobial compounds had a high concentration of total phenols and flavonoids and a good anti-oxidant and anti-radical activity. In situ study showed that natural antimicrobials mix, applied on the carrot surface, reduced significantly the count of the initial mesophilic total flora (TMF), molds and yeasts and allowed an extension of the shelf-life of carrots by two days as compared to the control. However, the chemical treatment (mix of peroxyacetic acid and hydrogen peroxide) showed antifungal activity and a slight reduction of TMF.
... PAA. is an effective antimicrobial that loses effectiveness slowly in the presence of organic matter [149][150][151]. Therefore, in comparison to chlorine sanitation, PAA. is more suited for the nut industry due to its antimicrobial stability under varying conditions such as dirt and debris that the introduction of inshell nuts imposes on the wash water [152]. The maximum residue of PAA. ...
... In particular, the inoculum of S. Thompson, S. Derby and S. Napoli was standardized in PBS at about 5 × 10 5 CFU mL −1 . The carrot samples were aseptically submerged into Salmonella suspension for 30 min at room temperature (Ruiz-Cruz et al., 2007) and stand to dry 30 min in a class II biological safety cabinet. CEO was diluted in sterile PBS as described in section Determination of Minimal Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) to reach the final concentration of 5 µL mL −1 . ...
Article
Full-text available
Chemical disinfectants represent one of the commonly used practice in minimally processed vegetables food-chain. However, the scarce safety and sustainability of these agents force food industry to move toward more sustainable “green washing solutions.” Among the latter, while the application of plant derivates for the control of several pathogens is already well-known, the potential anti-Salmonella activity of Coriandrum sativum seeds derivates is still unexplored and was therefore investigated in this study. In detail, Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of different coriander seed derivates (i.e., essential oil, hydrosol, and ethanolic extract) were determined by broth dilution against six Salmonella enterica strains isolated from fresh and minimally processed fruits and vegetables. Only the essential oil (EO) was effective in vitro with strain-dependent results. In addition, when mixed in co-culture, the strains were more sensitive to the essential oil treatment. Chemical investigations allowed to define (s)-(+)-linalool as major compound in the essential oil, and to underline interesting phenolic content with correlated antioxidant capacity. A cocktail of three strains of different serovars was selected and employed for a preliminary in situ trial on stick carrots. The obtained results allowed to establish that the application of coriander seed EO at concentrations of 5 μL mL−1 was able to reduce and contain the growth of the Salmonella cocktail up to 24 h at 10°C. Good sensory evaluation results were obtained by applying this EO concentration as washing treatment, especially in terms of color parameter. Further studies should be undertaken to emphasize the upstream activity, improving the formulation or exploiting a combined effect with other sanitizers or treatments (e.g., physical treatments). The present study contributes to the knowledge on coriander derivates activity against Salmonella spp. and on the potential application as sustainable washing treatment in removing this pathogen from fresh cut carrots.
... Dip inoculation was chosen to simulate such a process because immersion could be a suspected point that caused contamination in the food industry (Ruiz-Cruz, Acedo-Félix, Díaz-Cinco, Islas-Osuna, & González-Aguilar, 2007). All inocula were prepared by centrifugation (5000 g, 10 min), washed twice with saline and resuspended in peptone water to give bacterial suspensions with a cell density of about 10 7 CFU/mL. ...
Article
In the present study, the synergistic disinfection efficacy of low concentration electrolyzed water (LcEW) (free available chlorine, 4mg/L) combined with brief heat enhancement was evaluated and the bactericidal mechanism was investigated by atomic force microscopy (AFM). The inactivation kinetics of Escherichia coli O157:H7 and Salmonella Typhimurium on organic carrot were fitted with Weibull model to evaluate the synergistic effects. LcEW is effective at inactivating E. coli O157:H7 and S. Typhimurium on organic carrots, and the efficacy is dependent on the temperature. The combined treatment with LcEW at 80°C resulted in decimal reductiontime(TR)of7.42and3.27sforE.coliO157:H7andS.Typhimurium,respectively.Thereactiveoxygen species generated from LcEW were responsible for the microbial inactivation. In addition, AFM observation of E. coli O157:H7 and S. Typhimurium revealed morphological alterations in the bacterial cell structure, which illustrated the damage of cell membrane injury and intracellular component leakage. Quality attributes of carrot treated with LcEW and short-time heating (70°C, 1min) were not significantly different from controls. Compared to the control group, the combined treatment exhibited significantly (P < 0.05) greater inhibition of naturally occurring microbiota on organic carrots during storage at 4°C. Consequently, the application of LcEW combined with short-time heat improved safety of organic carrot, without negatively affecting the sensory properties, which can be explored by the organic industry.
... An increasing number of recent reports show contamination and prevalence of L. monocytogenes in fresh produce. L. monocytogenes bacteria have been isolated from market or restaurant produce such as cabbage [12], corn [13], carrots [14][15][16], lettuce [17][18][19][20][21][22][23], cucumbers [1,24,25], parsley [11,26,27] and salad vegetables [11,25,28,29]. Outbreaks of L. monocytogenes infections associated with fresh produce have been reported in various parts of the world [24]. ...
Article
Full-text available
Listeria monocytogenes, a member of the genus Listeria, is widely distributed in agricultural environments, such as soil, manure and water. This organism is a recognized foodborne pathogenic bacterium that causes many diseases, from mild gastroenteritis to severe blood and/or central nervous system infections, as well as abortion in pregnant women. Generally, processed ready-to-eat and cold-stored meat and dairy products are considered high-risk foods for L. monocytogenes infections that cause human illness (listeriosis). However, recently, several listeriosis outbreaks have been linked to fresh produce contamination around the world. Additionally, many studies have detected L. monocytogenes in fresh produce samples and even in some minimally processed vegetables. Thus L. monocytogenes may contaminate fresh produce if present in the growing environment (soil and water). Prevention of biofilm formation is an important control measure to reduce the prevalence and survival of L. monocytogenes in growing environments and on fresh produce. This article specifically focuses on fresh produce–associated listeriosis outbreaks, prevalence in growing environments, contamination levels of fresh produce, and associated fresh produce safety challenges.
... The internationally recommended concentration for chlorine-based compounds used for rinsing produce is between 50 and 100 ppm of free chlorine [21]. This range is reported to achieve a pathogen reduction of approximately 1-2 log CFU/g [22]. The effectiveness of chlorinebased sanitizers decreases in the presence of organic matter in produce wash-water [23]. ...
Article
Full-text available
Fruits and vegetables are high in nutrients that are essential for a healthy lifestyle. However, they also harbor an extensive array of microorganisms such as bacteria, which can be beneficial, neutral, or pathogenic. Foodborne pathogens can contaminate produce at any stage from the farm to the consumer’s table. Appropriate washing techniques using sanitizers can reduce the risk of pathogen contamination. Issues related to maintaining concentration, efficacy, and other problems have been a challenge for the food industry and, when left unresolved, have led to different outbreaks of foodborne illnesses. In this study, the efficacy of a lytic bacteriophage cocktail was examined for its ability to infect and reduce the contamination of Escherichia coli O157:H7 (E. coli O157:H7), in media with a high organic load, using a microplate technique. The study was conducted for 3 h to determine if the bacteriophage cocktail could reduce the pathogen in the presence of a high organic load. A significant (p < 0.05) reduction in the population of E. coli O157:H7 was observed, representing a 99.99% pathogen reduction at the end of 3 h. Fresh spinach leaves were washed in sterile potable or organic water (~9000 ppm organic load) containing E. coli O157:H7 and a bacteriophage cocktail to study the effectiveness of bacteriophages against the foodborne pathogen. Results indicated that the bacteriophage significantly (p < 0.05) reduced the contamination of E. coli O157:H7 in both situations. The study also demonstrated the bacteriophages’ ability to infect and reduce the pathogen in an organic-rich environment. This characteristic differs from commercially available sanitizers that have demonstrated a tendency to bind with the available organic load. Thus, these studies highlight the advantage of employing bacteriophages during produce wash to eliminate foodborne pathogen contamination on fruits and vegetables.
... Knowledge about the microbial reduction with adherent pathogens is important, once the sanitizer efficiency can be impaired as a function of the surface characteristics (Ruíz-Cruz, Félix, Cinco, Osuna, & Aguilar, 2007). It is known that harvesting and post-harvesting of fruits and vegetables can cause significant tissue damage and promote the growth of pathogenic bacteria. ...
Article
The objective of this study was to evaluate the effect of the use of different chemical compounds combined with ultrasound bath on the sanitization of minimally processed carrots. The sanitizers sodium hypochlorite, peracetic acid, and sodium dichloroisocyanurate were investigated, all of them associated with the ultrasound bath, and the aerobic mesophiles and E. coli counts were evaluated. Sodium hypochlorite associated with ultrasound reduced the population of aerobic mesophiles and E. coli by 0.23 and 1.88 log cycles, respectively. For sodium dichloroisocyanurate associated with ultrasound, the reduction was 3.06 and 2.76 log cycles, while for the association with peracetic acid, this reduction was 2.72 and 2.35 log cycles. Thus, the effect of the ultrasound bath and sodium dichloroisocyanurate increased the decontamination efficiency of the minimally processed carrots. In addition, there is an alternative to the use of sodium hypochlorite, once they are not involved in reactions with organic compounds and the formation of trihalomethanes, which are harmful to health.
... For example, hypochlorous acid can react with organic matter present in the washing water and can create byproducts such as chlorine vapors and trihalomethanes, both of which are known to be highly toxic to humans (Christopher et al. 1980;Ivancev-Tumbas et al. 1999;Rico et al. 2007). The use of chlorinated compounds also raises environmental issues (Rico et al. 2007;Ru ız-Cruz et al. 2007a). Therefore, the industry is searching for alternative disinfectant treatments to chlorine-based compounds for fresh fruit and vegetables. ...
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Survival of a nontoxigenic isolate of Escherichia coli O157:H7 at low pH (pH 3.0) was examined over prolonged time periods for each of three population types: exponential-phase cells, stationary-phase cells, and acid-adapted exponential-phase cells. In each population, approximately 5 × 10 ⁴ CFU ml ⁻¹ were detected after a 24-h incubation at pH 3.0. Even after 3 days at pH 3.0, significant numbers of survivors from each of the three populations could be detected. The high level of acid tolerance exhibited by these survivors was found to be quickly lost once they were transferred to conditions which permitted growth to resume, indicating that they were not mutants. Proton flux measurements on the three populations of cells revealed that the initial rates of viability loss at pH 3.0 correlated well with net proton accumulation. Cells showing a high initial rate of viability loss (exponential-phase cells) accumulated protons at the highest rate, whereas resistant populations (adapted or stationary-phase cells) accumulated protons only slowly. Differences in the protein composition of the cell envelope between the three populations were studied by two-dimensional polyacrylamide gel electrophoresis. Complex differences in the pattern of proteins expressed by each population were uncovered. The implications of these findings are discussed in the context of a possible model accounting for acid tolerance in this important food-borne pathogen.
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The influence of modified-atmosphere packaging, storage temperature, and time on survival and growth of Escherichia coli O157:H7 inoculated onto shredded lettuce, sliced cucumber, and shredded carrot was determined. Growth of psychotrophic and mesophilic microorganisms and changes in pH and sensory qualities of vegetables, as judged by subjective evaluation, were also monitored. Packaging under an atmosphere containing 3% oxygen and 97% nitrogen had no apparent effect on populations of E. coli O157:H7, psychotrophs, or mesophiles. Populations of viable E. coli O157:H7 declined on vegetables stored at 5 degrees C and increased on vegetables stored at 12 and 21 degrees C for up to 14 days. The most rapid increases in populations of E. coli O157:H7 occurred on lettuce and cucumbers stored at 21 degrees C. These results suggest that an unknown factor(s) associated with carrots may inhibit the growth of E. coli O157:H7. The reduction in pH of vegetables was correlated with initial increases in populations of E. coli O157:H7 and naturally occurring microfloras. Eventual decreases in E. coli O157:H7 in some samples, e.g., those stored at 21 degrees C, are attributed to the toxic effect of accumulated acids. Changes in visual appearance of vegetables were not influenced substantially by growth of E. coli O157:H7. The ability of E. coli O157:H7 to growth on raw salad vegetables subjected to processing and storage conditions simulating those routinely used in commercial practice has been demonstrated.
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Listeria monocytogenes acquired increased acid tolerance during exponential growth upon exposure to sublethal acid stress, a response designated the acid tolerance response (ATR). Maximal acid resistance was seen when the organism was exposed to pH 5.0 for 1 h prior to challenge at pH 3.0, although intermediate levels of protection were afforded by exposure to pH values ranging from 4.0 to 6.0. A 60 min adaptive period was required for the development of maximal acid tolerance; during this period the level of acid tolerance increased gradually. Full expression of the ATR required de novo protein synthesis; chloramphenicol, a protein synthesis inhibitor, prevented full induction of acid tolerance. Analysis of protein expression during the adaptive period by two-dimensional gel electrophoresis revealed a change in the expression of at least 23 proteins compared to the non-adapted culture. Eleven proteins showed induced expression while 12 were repressed, implying that the ATR is a complex response involving a modulation in the expression of a large number of genes. In addition to the exponential phase ATR, L.monocytogenes also developed increased acid resistance upon entry into the stationary phase; this response appeared to be independent of the pH-dependent ATR seen during exponential growth.
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The efficacy of sanitizers in killing human pathogenic microorganisms on a wide range of whole and fresh-cut fruits and vegetables has been studied extensively. Numerous challenge studies to determine the effects of storage conditions on survival and growth of pathogens on raw produce have also been reported. Results of these studies are often difficult to assess because of the lack of sufficient reporting of methods or, comparatively, because of variations in procedures for preparing and applying inocula to produce, conditions for treatment and storage, and procedures for enumerating pathogens. There is a need for a standard method to accurately determine the presence and populations of pathogenic microorganisms on produce. The adoption of standard, well-characterized reference strains would benefit a comparative assessment of a basic method among laboratories. A single protocol will not be suitable for all fruits and vegetables. Modifications of a basic method will be necessary to achieve maximum recovery of pathogens on various types of produce subjected to different sanitizer or storage treatments. This article discusses parameters that must be considered in the course of developing a basic standard method against which these modifications could be made.
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Chlorine is widely used as a sanitizer to maintain the microbial quality and safety of fresh-cut produce; however, chlorine treatment lacks efficacy on pathogen reduction, especially when the fresh-cut processing water contains heavy organic loads. A more efficacious sanitizer that can tolerate the commercial processing conditions is needed to maintain microbial safety of fresh-cut produce. This study evaluated the efficacy of Escherichia coli O157:H7 reduction on fresh-cut carrots using new and traditional sanitizers with tap water and fresh-cut processing water scenarios. Fresh-cut carrot shreds inoculated with E. coli O157:H7 were washed in sanitizer solutions including 200 ppm chlorine, citric acid-based sanitizer (Pro-San), 80 ppm peroxyacetic acid-based sanitizer (Tsunami 100), and 1,000 ppm acidified sodium chlorite (SANOVA) prepared in fresh tap water or simulated processing water with a chemical oxygen demand level of approximately 3,500 mg/liter. Samples were packaged and stored at 5 degrees C. Microbial analyses performed at days 0, 7, and 14 indicate that the organic load in the process water significantly affected the efficacy of chlorine on pathogen removal and was especially evident on samples tested during storage. Acidified sodium chlorite provided a strong pathogen reduction even under process water conditions with up to a 5.25-log reduction when compared with the no-wash control. E. coli O157:H7 was not recovered on acidified sodium chlorite-treated samples during the entire 14 days of storage, even following an enrichment step. These results suggest that acidified sodium chlorite holds considerable promise as an alternative sanitizer of fresh-cut produce.
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Quality and safety of fresh produce depend on their microbiological flora. Every step from production through consumption will influence the microbiology of fresh produce. Improper handling and unsanitary equipment lead to increased populations of microorganisms on fresh fruits and vegetables and can compromise quality and safety. Processing steps such as cutting and peeling usually increase the population of microorganisms and shorten shelf life. Using techniques to extend shelf life can increase the risk of safety problems developing and therefore need to be carefully evaluated. Proper use of disinfectants can complement an effective sanitation program but should not be relied upon to eliminate pathogenic microorganisms from contaminated produce. Copyright ©, International Association of Milk, Food and Environmental Sanitarians.
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Surveys were made of commercial processing lines used to prepare fresh-cut vegetables such as chopped salad ingredients, carrot sticks, and cauliflower florets. Washing and chlorinated water dips only partially removed the microorganisms that were intrinsic to the vegetables. Major sources of in-plant contamination were the shredders used to prepare chopped lettuce and coleslaw. Gram-negative rods were the predominant microflora with species of Pseudomonas being most numerous; many were psychrotrophic. Only low numbers of lactic acid bacteria and fungi were recovered. Copyright © International Association of Milk, Food and Environmental Sanitarians.
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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.
Article
Fresh-cut cantalcupe has been recalled due to the possible presence of Listeria monocytogenes. Several studies have reported that naturally occurring microflora of vegetable surfaces may be antagonistic to pathogen attachment, growth or survival. To test this possibility for L. monocytogenes and cantaloupes, whole melon were treated with water, ethanol (70%) or chlorine (200 ppm) to reduce the native microflora on the melon surfaces. Treated or untreated melons were immersed in a six strain cocktail of L. monocytogenes (107 CFU/mL) for 10 min and then allowed to dry for 1 h inside a biosafety cabinet followed by storage at 5, 10 and 20C for 15 days. Fresh-cut pieces prepared from the treated or untreated melons and directly inoculated with L. monocytogenes (3.48 log CFU/g) were stored under the same conditions listed above. Populations of L. monocytogenes and five classes of native microflora were investigated. Growth of L. monocytogenes in sterile or nonsterile rind and fresh-cut homogenates was also studied. The population of L. monocytogenes recovered from inoculated (103 to 108 CFU/mL) whole melons given no disinfection treatment or washed with water was significantly less (P < 0.05) than that recovered from melons treated with chlorine or EtOH. In general, populations of L. monocytogenes declined on the surface of treated and untreated whole melons and on fresh-cut pieces over the 15 days storage period at the temperatures tested. However, the decline in pathogen populations was less rapid in the presence of reduced populations of native microflora. Higher populations of L. monocytogenes were attained in sterile tissue homogenates than in nonsterile homogenates. Addition of yeast and mold to sterile rind homogenates was highly inhibitory to growth and survival of the pathogen. The results of this study indicate that native microflora of whole cantaloupe inhibited attachment to rind surfaces as well as survival and growth of L. monocytogenes on cantaloupe surfaces and homogenized fresh-cut pieces. Thus, L. monocytogenes recontamination of melons having a reduced level of native microflora following application of a disinfection treatment may be a food safety concern.
Article
The primary method to eliminate, or significantly reduce, pathogens on produce is strict adherence to Good Agricultural Practices (GAPs), Good Manufacturing Practices (GMPs), Hazard Analysis Critical Control Points (HACCP), and other relevant strategies that prevent contamination from occurring. This includes the concept of "good management practices" as described in the Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables (FDA 1998). Although the frequency of produce contamination by pathogens is thought to be very small, there are no known mitigation strategies that will completely remove pathogens after contamination has occurred while maintaining produce freshness. A variety of mitigation regimens and sanitizers are available to reduce microbial populations depending upon the type of produce involved. Washing and sanitizing efficiencies depend on several factors, including characteristics of the produce surface, water quality, cleaner/sanitizer used, contact time, and presence and type of scrubbing action. Based on reported data, it is likely that different sanitation mitigation strategies are needed for different produce items.
Article
Shredded carrots are particularly susceptible to microbial growth and quality deterioration as a result of a large cut surface area to mass ratio. Acidified sodium chlorite (ASC) in the concentration range 500–1200 µL L−1 has been shown to have stronger efficacy against pathogens and spoilage bacteria than chlorine and does not form carcinogenic products. However, ASC in this concentration range aggravates tissue damage. The objective of this study was to optimize ASC treatment parameters to balance antimicrobial activity with quality retention of shredded carrots. Shredded carrots were immersed for either 1 min in 100, 250 or 500 µL L−1 ASC solutions or 2 min in 200 µL L−1 chlorine or water (control). Treated samples were spin-dried and packaged in polypropylene bags and stored at 5 °C for up to 21 days. Carrots were evaluated at 7-day intervals for visual appearance, package atmosphere composition (O2 and CO2), product firmness, tissue electrolyte leakage and pH. The microbial growth, including total aerobic bacterial counts, total coliforms/Escherichia coli, yeast and mold counts and lactic acid bacterial counts on the products was also determined. Treatments with all concentrations of ASC reduced the aerobic bacterial counts, coliform/E. coli counts, yeast mold and counts and lactic acid bacterial populations by 1.2–2.0 log cfu g−1 when compared with the water-washed and unwashed samples. During storage, unwashed samples had a sharp increase in lactic acid bacterial populations accompanied by a sharp decline in pH readings and rapid loss in firmness and tissue integrity; samples washed with 100 µL L−1 ASC maintained the best overall visual quality, accompanied by the retention of tissue integrity and firmness. Therefore, 100 µL L−1 was determined as the optimum concentration of ASC for maintaining overall quality and firmness, inhibiting microbial growth and prolonging the shelf-life of shredded carrots. Copyright © 2006 Society of Chemical Industry
Article
Cut lettuce salads and shredded carrots were prepared according to four different procedures in order to determine the influence of various operations on the shelf-life of these ‘minimally processed’ foods. In particular, the level of active chlorine used or its residue after washing as well as the processing time were considered. The results emphasize the role of free chlorine in reduction of the contamination level and its effectiveness toward Pseudomonadaceae and Enterobacteriaceae. Moreover a 12-h delay without refrigeration, after pre-washing or removal of ends, caused a lengthening of the processing time, enough to allow microbial proliferation and subsequent shortening of shelf-life. Shelf-life extension and the improvement of safety and quality of these products can be obtained by means of adequate processing operations.
Article
The influence of dipping shredded lettuce in carrot juice or adding carrot juice to Brie cheese and frankfurter homogenates on survival and growth of Listeria monocytogenes was studied. Viable populations were monitored over 14 days of incubation at 5, 12 or 20° C. Aerobic mesophilic micro-organisms were also enumerated. L. monocytogenes grew at all incubation temperatures on lettuce not treated with carrot juice. Treatment with 20 or 50% carrot juice resulted in significantly (P ≤ 0·05) lower populations of viable L. monocytogenes throughout the 14-day incubation period at 5° C. Treatment retarded the growth of L. monocytogenes on lettuce incubated at 12° C but was without affect at 20° C. Increased amounts of carrot juice, from 0 to 2, 5 or 10%, resulted in significant reductions in viable cells of L. monocytogenes in Brie cheese incubated at 5° C but not at 12 or 20° C. Carrot juice, when added at levels up to 10%, was ineffective in controlling the growth of L. monocytogenes in frankfurter homogenate, regardless of the incubation temperature. Treatment with carrot juice failed to influence growth of aerobic mesophilic micro-organisms in lettuce, cheese and frankfurter, indicating that microflora naturally present in these foods or in the carrot juice used to supplement them are resistant to antilisterial components in the juice.
Article
A micro sample digestion technique for the determination of chemical oxygen demand (COD) is described. An automated spectrophotometric measurement of the appearance of chromium(III) after sample digestion completes the method. Adequate sensitivity at 600 nm is achieved by using a 50 mm flowcell to measure COD values in the range of 3-900 mg/l. The semi-automated method is compared to the standard method with respect to precision, accuracy, ease of analysis, and comparability of data.
Article
Carrot slices immersed in a potassium phosphate buffer (0.1 mol/l, pH 7.0) or carrot tissue macerated in the buffer had a lethal effect on Listeria monocytogenes. This antilisterial activity was suppressed by anaerobiosis, thiol compounds (1 mmol/l) and bovine serum albumin (0.05%) but was not affected by sodium ascorbate (200 mmol/l), propyl gallate (25 mmol/l), catalase (1100 U/ml), superoxide dismutase (357 U/ml), or chelating agents (10 mmol/l). Free-radical scavengers had no effect at 10 mmol or 50 mmol/l but histidine and diazabenzocyclooctane at 100 mmol/l reduced the antilisterial activity. The addition of Tween 20, 0.05% (v/v), to carrot macerates improved the recovery of the activity in the supernatant liquid after centrifugation at 10,000 g for 2 min. The addition of higher concentrations of the detergent to the macerate reduced the antilisterial activity.
Article
When shredded or sliced carrots were inoculated with Listeria monocytogenes the number of viable listerias decreased rapidly. On carrot slices stored at 8 degrees C there was a decrease after 3d followed by an increase, after 7d, to numbers similar to those present initially. The numbers of spoilage micro-organisms increased throughout storage at 8 degrees C. Carrots macerated in a Stomacher Lab Blender also showed an antilisterial activity which resulted in a decrease in number of viable bacteria and in sublethal damage. The effect was shown by five carrot cultivars and acted on nine strains of L. monocytogenes and single strains of L. innocua, L. ivanovii, L. seeligeri, L. melshimeri. This antilisterial effect was heat-labile, was inactivated after a few hours at 4 degrees C or at 30 degrees C and was active over the pH range 5.8 to 7.0. Maceration of carrots in an Atomix blender for 1 min or in liquid nitrogen destroyed the antilisterial activity.
Article
Environmental factors such as temperature, pH and nutrient level affect enterobacterial acid sensitivity, as do the presence of phosphate and Na+ and the extent of aeration. The mechanisms governing these effects are partially understood and the involvement of phoE, fur and atp in acid tolerance, of phoE, envZ, tonB, (p)ppGpp and cAMP in salt-induced acid sensitivity and of rpoS in stationary-phase acid tolerance are of particular interest. It should be noted that surface attachment enhances acid resistance.
Article
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.
Article
Purified ethanolic extracts of peeled and shredded carrots showed an antimicrobial effect against a range of food-borne micro-organisms. The minimum inhibitory concentration, expressed as mg ml-1 dried carrot material used for the extraction were: Leuconostoc mesenteroides, 27; Listeria monocytogenes, > 27 < 55; Staphylococcus aureus, > 27 < 55; Pseudomonas fluorescens, > 55 < 110; Candida lambica, > 55 < 110; Escherichia coli, > 110 < 220. The antimicrobial activity was not linked to phenolic compounds but was presumably due to apolar components. Free saturated fatty acid (dodecanoic acid) and methyl esters of saturated fatty acids (of dodecanoic and pentadecanoic acids) were identified in purified active extracts of carrots by gas chromatography coupled to mass spectrometry and could be responsible for the antimicrobial activity. This effect did not seem to play a role in the resistance of shredded carrots to microbial spoilage, although the antimicrobial activity was present in fresh carrots at concentrations sufficient to inhibit spoilage bacteria.
Article
A variety of wholesale and retail packaged vegetables and salads were inoculated with a mixture of strains of Listeria monocytogenes and incubated at 4 and 10°C. Whole rutabagas, butternut squash, and onions, as well as packaged Caesar salad, carrots, coleslaw mix, and stir-fry vegetables were purchased from local supermarkets in the Ottawa area. L. monocytogenes population levels remained constant on all fresh-cut vegetables stored at 4°C for 9 days, except for carrots and butternut squash: counts of cell numbers declined on carrots and increased on the butternut squash. Fresh-cut vegetables stored at 10°C, however, supported good growth of L. monocytogenes on all vegetables tested, except for chopped carrots, where the population decreased approximately 2 log units over a 9-day storage period. As in the situation with the produce stored at 4°C, butternut squash supported the highest rate of cell growth. In addition, Caesar salad and coleslaw mix were kept at 25°C for 1 or 2 days before subsequent storage at 4 or 10°C to simulate extreme temperature-abuse conditions. In Caesar salad stored at 4°C, by day 6 an initial 24- and 48-h temperature abuse at 25°C led to a 1.21- and 2.55-log-unit population increase, respectively, over the control. Similar increases were observed on Caesar salads stored at 10°C. Compared to Caesar salad, coleslaw mix temperature-abused at 25°C and then stored at 4°C supported slightly greater increases in the population of L. monocytogenes, i.e., a 3.22- and 3.83-log-unit increase over the control for the 1- and 2-day abused samples, respectively. Coleslaw mix samples temperature-abused and then stored at 10°C, however, only showed log unit increases of 1.75 and 1.94, respectively, compared to the controls. These results point to the importance of strict temperature control to prevent or reduce the growth of L. monocytogenes cells on fresh-cut vegetables.
Article
The focus of this study was to determine the efficacy of various chemicals in eliminating 2.04 to 3.23 log10 CFU/g of Escherichia coli O157:H7 from alfalfa seeds and to determine the survivability of the pathogen on seeds stored for prolonged periods at three temperatures. Significant (P < or = 0.05) reductions in populations of E. coli O157:H7 on inoculated seeds were observed after treatments with 500 and 1,000 ppm of active chlorine (as Ca[OCl]2) for 3 but not 10 min and with > or =2,000 ppm of Ca(OCl)2 regardless of pretreatment with a surfactant. Treatment with 20,000 ppm of active chlorine failed to kill 2.68 log10 CFU/g of seeds. Acidified NaClO2 (500 ppm) was effective in reducing populations of the pathogen by >2 logs per g. Acidified ClO2 significantly reduced populations of E. coli O157:H7 on seeds at concentrations > or =100 ppm, and 500 ppm of ClO2 reduced the pathogen from 2.7 log10 CFU/g to <0.5 CFU/g. Chlorine (as NaOCl) was not effective at concentrations < or =1,000 ppm; significant reduction was achieved only after treatment with 2,000 ppm for 3 or 10 min. Notable reduction in populations was observed after treatment with 30 or 70% C2H3OH, but there was a dramatic decrease in germination percentage. Treatment with 0.2% H2O2 significantly reduced populations, and the organism was not detected by direct plating after treatment with > or =1% H2O2. Significant reduction in population of E. coli O157:H7 occurred after treatment with 1% trisodium phosphate, 40 ppm of Tsunami and Vortexx, and 1% Vegi-Clean. A significant decrease in the number of E. coli O157:H7 on dry seeds was observed within 1 week of storage at 25 and 37 degrees C, but not at 5 degrees C. Between 1 and 38 weeks, populations on seeds stored at 5 degrees C remained relatively constant. The pathogen was recovered from alfalfa seeds initially containing 3.04 log 10 CFU/g after storage at 25 or 37 degrees C for 38 weeks but not 54 weeks.
Article
The behavior of Escherichia coli O157:H7 on alfalfa seeds subjected to conditions similar to those used commercially to grow and market sprouts as it is affected by applications of NaOCl, Ca(OCl)2, acidified NaClO2, acidified ClO2, Na3PO4, Vegi-Clean, Tsunami, Vortexx, or H2O2 at various stages of the sprouting process was determined. Application of 2,000 ppm of NaOCl, 200 and 2,000 ppm of Ca(OCl)2, 500 ppm of acidified ClO2, 10,000 ppm of Vegi-Clean, 80 ppm of Tsunami, or 40 and 80 ppm of Vortexx to germinated seeds significantly reduced the population of E. coli O157:H7. With the exception of acidified NaOCl2 at 1,200 ppm, spray applications of these chemicals did not significantly reduce populations or control the growth of E. coli O157:H7 on alfalfa sprouts during the sprouting process. Populations of E. coli on alfalfa sprouts peaked at 6 to 7 log10 CFU/g 48 h after initiation of the sprouting process and remained stable despite further spraying with chemicals. The population of E. coli O157:H7 on sprouts as they entered cold storage at 9 +/- 2 degrees C remained essentially unchanged for up to 6 days. None of the chemical treatments evaluated was able to eliminate or satisfactorily reduce E. coli O157:H7 on alfalfa seeds and sprouts. Observations on the ability of E. coli O157:H7 to grow during production of alfalfa sprouts not subjected to chemical treatments are similar to those from a previous study in our laboratory on the behavior of Salmonella Stanley. Our results do not reveal a chemical treatment method to eliminate the pathogen from alfalfa sprouts. We have demonstrated that currently recommended procedures for sanitizing alfalfa seeds fail to eliminate E. coli O157:H7 and that the pathogen can grow to populations exceeding 7 1og10 CFU/g of sprouts produced using techniques not dissimilar to those used in the sprout industry.
Article
Several outbreaks of salmonellosis associated with alfalfa sprouts have been documented in the United States since 1995. This study was undertaken to evaluate various chemical treatments for their effectiveness in killing Salmonella on alfalfa seeds. Immersing inoculated seeds in solutions containing 20,000 ppm free chlorine (Ca[OCl]2), 5% Na3PO4, 8% H2O2, 1% Ca(OH)2, 1% calcinated calcium, 5% lactic acid, or 5% citric acid for 10 min resulted in reductions of 2.0 to 3.2 log10 CFU/ g. Treatment with 1,060 ppm Tsunami or Vortex, 1,200 ppm acidified NaClO2, or 5% acetic acid were less effective in reducing Salmonella populations. With the exceptions of 8% H2O2, 1% Ca(OH)2, and 1% calcinated calcium that reduced populations by 3.2, 2.8, and 2.9 log10 CFU/g, respectively, none of treatments reduced the number of Salmonella by more than 2.2 log10 CFU/g without significantly reducing the seed germination percentage. Treatment with 5% acetic, lactic, or citric acids substantially reduced the ability of seeds to germinate. Treatment with 1% Ca(OH)2 in combination with 1% Tween 80, a surfactant, enhanced inactivation by 1.3 log10 CFU/g compared to treatment with 1% Ca(OH)2 alone. Presoaking seeds in water, 0.1% EDTA, 1% Tween 80, or 1% Tween 80 plus 0.1% EDTA for 30 min before treatment with water, 2,000 ppm NaOCl, or 2% lactic acid had a minimal effect on reducing populations of Salmonella. Results indicate that, although several chemical treatments cause reductions in Salmonella populations of up to 3.2 log10 CFU/g initially on alfalfa seeds when analyzed by direct plating, no treatment eliminated the pathogen, as evidenced by detection in enriched samples.
Article
The adaptation of Escherichia coli O157:H7 cells to acid conditions has been reported. This study showed the behavior of three strains of E. coli O157:H7 in two different physiological stages (acid shocked and control cells), inoculated in five fruit pulps stored at 4 degrees C for up to 30 days. The three strains of E. coli O157:H7 inoculated in grape pulp could be recovered up to day 30. E. coli O157:H7 strains survived for 4 days in all fruit pulps tested with different pH values (2.51 to 3.26), with the exception of acid-shocked cells of E. coli O157:H7 strain 933, which did not survive in "cajá" (Spodias lutea L.) pulp. The results clearly indicated that acid resistance can persist for long periods during storage at 4 degrees C. The protection conferred by acid adaptation suggests that acid-resistant organisms will be better equipped to outlast these acid challenges. The survival of E. coli O157:H7 in fruit pulps with a low pH, stored under refrigeration, is of extreme importance due to the high virulence of this microorganism. The viability of microorganisms was dependent on the viscosity index of fruit pulps. Less viscous pulps supported the bacteria survival longer than more viscous fruit pulps.
Article
The microbial quality of five types of fresh produce obtained at the retail level was determined by standard quantitative techniques. These techniques included aerobic plate count (APC), total coliform counts, Escherichia coli counts, and yeast and mold counts. Three different methods were used to determine total coliform counts, which consisted of MacConkey agar plate counts, Colicomplete most probable number counts, and Petrifilm E. coli (EC) plate counts. The mean APCs for sprouts, lettuce, celery, cauliflower, and broccoli were 8.7, 8.6, 7.5, 7.4. and 6.3 log10 CFU/g, respectively. MacConkey agar counts indicated that 89 to 96% of the APCs consisted of gram-negative bacteria. Yeast and mold counts were in a range expected of fresh produce. Fresh produce was also analyzed for human pathogens. Samples were analyzed for Staphylococcus spp., Bacillus spp., Salmonella spp., Listeria spp., and Campylobacter spp. One isolate of Staphylococcus was found to be enterotoxigenic, and one species of Bacillus was also toxigenic. Neither Salmonella spp. nor Campylobacter spp. were detected in any of the produce samples. A variety of Listeria spp., including Listeria monocytogenes, were found in fresh produce.
Article
To evaluate the microbial spoilage, formation of biogenic amines and shelf life of chilled fresh and frozen/thawed salmon packed in a modified atmosphere and stored at 2 degrees C. The dominating microflora, formation of biogenic amines and shelf life were studied in two series of storage trials with naturally contaminated fresh and thawed modified atmosphere-packed (MAP) salmon at 2 degrees C. Photobacterium phosphoreum dominated the spoilage microflora of fresh MAP salmon at more than 10(6) cfu g(-1) and the activity of this specific spoilage organism (SSO) limited the shelf life of the product to ca 14 and 21 d in the two experiments. Despite the high levels of P. phosphoreum, less than 20 mg kg(-1) histamine was observed in fresh MAP salmon prior to sensory spoilage. Freezing eliminated P. phosphoreum and extended the shelf life of MAP salmon at 2 degrees C by 1-2 weeks. Carnobacterium piscicola dominated the spoilage microflora of thawed MAP salmon and probably produced the ca 40 mg kg(-1) tyramine detected in this product at the end of its shelf life. Photobacterium phosphoreum dominated the spoilage microflora of fresh MAP salmon but produced only small amounts of biogenic amines in this product. The elimination of P. phosphoreum by freezing allowed this bacteria to be identified as the SSO in fresh MAP salmon. The identification of P. phosphoreum as the SSO in fresh MAP salmon facilitates the development of methods to determine and predict the shelf life of this product, as previously shown with fresh MAP cod.
Article
Microorganisms are the major cause of spoilage of most seafood products. However, only a few members of the microbial community, the specific spoilage organisms (SSOs), give rise to the offensive off-flavours associated with seafood spoilage. Combining microbial ecology, molecular techniques, analytical chemistry, sensory analysis and mathematical modelling allows us to characterise the SSOs and to develop methods to determine, predict and extend the shelf life of products.