Article

Effect of chemical sanitizer combined with modified atmosphere packaging on inhibiting Escherichia coli O157:H7 in commercial spinach

July 2008
Food Microbiology 25(4):582-7

July 2008
25(4):582-7

DOI:10.1016/j.fm.2008.02.003

Source
PubMed

Authors:

Sun-Young Lee

Chung-Ang University

Escherichia coli O157:H7 contaminated spinach has recently caused several outbreaks of human illness in the USA and Canada. However, to date, there has been no study demonstrating an effective way to eliminate E. coli O157:H7 in spinach. Therefore, this study was conducted to investigate the effect of chemical sanitizers alone or in combination with packaging methods such as vacuum and modified atmosphere packaging (MAP) on inactivating E. coli O157:H7 in spinach during storage time. Spinach inoculated with E. coli O157:H7 was packaged in four different methods (air, vacuum, N(2) gas, and CO(2) gas packaging) following treatment with water, 100 ppm chlorine dioxide, or 100 ppm sodium hypochlorite for 5 min at room temperature and stored at 7+/-2 degrees C. Treatment with water did not significantly reduce levels of E. coli O157:H7 in spinach. However, treatment with chlorine dioxide and sodium hypochlorite significantly decreased levels of E. coli O157:H7 by 2.6 and 1.1 log(10)CFU/g, respectively. Levels of E. coli O157:H7 in samples packaged in air following treatments grew during storage time, whereas levels were maintained in samples packaged in other packaging methods (vacuum, N(2) gas, and CO(2) gas packaging). Therefore there were significant differences (about 3-4 log) of E. coli O157:H7 populations between samples packed in air and other packaging methods following treatment with chemical sanitizers after 7 days storage. These results suggest that the combination of treatment with chlorine dioxide and packaging methods such as vacuum and MAP may be useful for improving the microbial safety of spinach against E. coli O157:H7 during storage.

Effect of modified atmosphere packaging on preserving various types of fresh produce: HYUN and LEE

Article

Full-text available

Jul 2017

Modified atmosphere packaging (MAP) is an effective preservation method for extending the shelf‐life of various foods. This study was conducted to investigate the applicability of MAP for improving the food quality and safety of various fresh produce during refrigeration storage. Thirteen kinds of fresh produce were washed with 100 ppm chlorine and then packaged in three different types of packaging film using two different methods (air and 100% CO 2 gas). Changes of the headspace gas composition, visual quality, microbial populations, and electrolyte leakage of the packaged samples were measured during storage at 4 ± 2 °C. MAP using CO 2 gas resulted in lower levels of total mesophilic bacteria, Escherichia coli /coliform, and yeast/mold in the fresh produce compared than the air packaging. In particular, MAP using CO 2 gas was effective at maintaining low levels of yeast and mold on grapes, soybean sprouts, and lotus roots during storage ( p ≤ .05). However, the visual quality of some of the fresh produce (e.g., green vegetables) during storage was affected by MAP. Higher levels of electrolyte leakage were observed in fresh produce packaged under CO 2 gas than that under air, except for grapes and lotus roots. Practical applications These results suggest that although MAP may be useful for improving the shelf‐life of some root vegetables and fruits during storage, its application would be limited for certain types of fresh produce because of quality deterioration. The result of this study could be used for developing the effective preservation method for fresh produce.

Inhibition of Listeria monocytogenes growth on fresh-cut produce with thyme essential oil and essential oil compound verbenone

Article

Oct 2016
POSTHARVEST BIOL TEC

The anti-listerial effectiveness of thyme essential oil (EO) and EO compounds camphor and verbenone was examined on fresh-cut lettuce, cantaloupe melon and pineapple with modified atmospheres and air in model packages at 4 and 8 °C. Listeria monocytogenes was found to be able to survive and grow in all atmospheres on melon and lettuce. However, on pineapple lowest survival was identified, presumably due to product pH. Thyme EO demonstrated the best anti-listerial effect, although direct application of the EO compromised product appearance. While camphor showed no anti-listerial effects, verbenone was found to have anti-listerial properties and maintained high sensory acceptance in fresh-cut fruit. The high growth rates of L. monocytogenes on melon were significantly reduced with the application of verbenone while being completely eliminated on pineapple. The use of thyme EO and verbenone as an antimicrobial dip was successfully applied to reduce growth of Listeria on fresh-cut melon and eliminate growth on pineapple; however growth-reduction was less pronounced in melon when compared to a conventional chlorine dip. Further research will be necessary to optimise conditions in fresh-cut produce treatments with natural products including verbenone and thyme EO to replace current chlorine treatments for improved food safety.

Efficacy of the combined application of oregano and rosemary essential oils for the control of Escherichia coli, Listeria monocytogenes and Salmonella Enteritidis in leafy vegetables

Article

Jan 2016
FOOD CONTROL

This study assessed the effect of the combined application of essential oils (EOs) from Origanum vulgare L. – oregano (OVEO) and Rosmarinus officinalis L. – rosemary (ROEO), alone or in combination at subinhibitory concentrations, against three pathogenic bacteria that are associated with fresh leafy vegetables: Listeria monocytogenes (L. monocytogenes), Escherichia coli (E. coli) and Salmonella enterica Serovar Enteritidis (S. Enteritidis). The inhibitory effects were evaluated by determining the minimum inhibitory concentration (MIC) and the fractional inhibitory concentration index (FICI) and assessing the viable cell counts in vegetable broth and artificially infected vegetables over time. Still, the effects of the EOs on native spoilage native flora were assessed. The MIC of OVEO was 0.6 μL/mL against the test strains either in single and mixed inoculum. The MIC of ROEO was 5 μL/mL against L. monocytogenes and E. coli and 10 μL/mL against S. Enteritidis in single inocula, whereas it was 10 μL/mL against the mixed inoculum. The FICI of the combined EOs was 0.5 against the mixed bacterial inoculum, which suggested a synergic interaction. The incorporation of OVEO and ROEO alone (MIC) or combined at different subinhibitory concentrations in vegetable broth resulted in a decrease in the viable cell counts of all test strains over 24 h. Similarly, the EOs alone or in the tested combinations reduced the viable cell counts of all test strains in experimentally infected fresh vegetables, besides to decrease the counts of spoiling native flora (mesophilic bacteria, enterobacteria and fungi). These findings reinforce the rational for the use of OVEO and ROEO in combination at subinhibitory concentrations to guarantee the safety and extend the shelf life of fresh vegetables.

Application of chlorine dioxide-based hurdle technology to improve microbial food safety–A review

Article

Jul 2022
INT J FOOD MICROBIOL

Zhao Chen

In recent years, a variety of conventional and novel food sanitation technologies have been developed, among which some may adversely affect the organoleptic properties and the nutrients of foods. The increasing demand for fresh-like foods has promoted efforts for developing innovative technologies. The detrimental effects of some technologies on the sensorial and nutritional values of foods could be overcome by using the hurdle technology that has become a promising approach. The interest in using chlorine dioxide for food sanitation has increased due to its many advantages over chlorine such as its powerful antimicrobial activity and less formation of harmful disinfection by-products. However, using chlorine dioxide to achieve a complete pathogen elimination from foods is still hard. In this context, chlorine dioxide has been combined with other technologies to enhance microbial food safety. This review, therefore, aims to present the application of chlorine dioxide-based hurdle technology through sequential or simultaneous treatments to control foodborne pathogens. The antimicrobial effects of chlorine dioxide combined with thermal and non-thermal physical, chemical, and biological technologies on various foodborne pathogens in a wide range of food commodities are critically reviewed.

Fresh Produce Safety and Quality: Chlorine Dioxide’s Role

Article

Full-text available

Jan 2022

Maintaining microbial safety and quality of fresh fruits and vegetables are a global concern. Harmful microbes can contaminate fresh produce at any stage from farm to fork. Microbial contamination can affect the quality and shelf-life of fresh produce, and the consumption of contaminated food can cause foodborne illnesses. Additionally, there has been an increased emphasis on the freshness and appearance of fresh produce by modern consumers. Hence, disinfection methods that not only reduce microbial load but also preserve the quality of fresh produce are required. Chlorine dioxide (ClO2) has emerged as a better alternative to chlorine-based disinfectants. In this review, we discuss the efficacy of gaseous and aqueous ClO2 in inhibiting microbial growth immediately after treatment (short-term effect) versus regulating microbial growth during storage of fresh produce (long-term effect). We further elaborate upon the effects of ClO2 application on retaining or enhancing the quality of fresh produce and discuss the current understanding of the mode of action of ClO2 against microbes affecting fresh produce.

Impact of Plant Pathogen Infection on Salmonella enterica subsp. enterica Serotype Typhimurium Persistence in Tomato Plants

Article

Full-text available

Nov 2020

We investigated whether the co-occurrence of phytopathogens (Clavibacter michiganensis subsp. michiganensis [Cmm] and Xanthomonas gardneri [Xg]) frequently encountered in tomato production and Salmonella enterica subsp. enterica serotype Typhimurium (strain JSG626) affects the persistence of these pathogens in tomato plant tissues during the early stages of plant growth. Cmm increased the recovery of Salmonella Typhimurium (up to 1.8 log CFU per plant at 21 days postinoculation [DPI]) from coinoculated tomato plants compared with plants inoculated with Salmonella Typhimurium alone (P < 0.05). Xg had no effect on Salmonella Typhimurium persistence in the plants. Increased persistence of Salmonella Typhimurium was also observed when it was inoculated 7 days after Cmm inoculation of the same plant (P < 0.05). In contrast, Salmonella Typhimurium reduced the population of both Cmm and Xg (up to 1.5 log CFU per plant at 21 DPI; P < 0.05) in coinoculated plants compared with plants inoculated with Cmm or Xg alone. The Xg population increased (1.16 log CFU per plant at 21 DPI; P < 0.05) when Salmonella Typhimurium was inoculated 7 days after Xg inoculation compared with plants inoculated with Xg alone. Our findings indicate that the type of phytopathogen present in the phyllosphere and inoculation time influence the persistence of Salmonella Typhimurium JSG626 and its interactions with phytopathogens cocolonized in tomato plants. Salmonella reduced the phytopathogen load in plant tissues, and Cmm enhanced the recovery of Salmonella from the coinoculated plant tissues. However, further investigations are needed to understand the mechanisms behind these interactions. HIGHLIGHTS

Effect of Cold Atmospheric Plasma Processing on Quality and Shelf-Life of Ready-to-Eat Rocket Leafy Salad

Article

Aug 2020
INNOV FOOD SCI EMERG

The effect of Cold Atmospheric Plasma (CAP) on ready-to-eat (RTE), fresh cut, leafy rocket salad (ready-to-eat arugula leaves packed in pouches of 125 g) was investigated, aiming at quality retention and shelf-life extension. CAP was generated via a surface dielectric barrier discharge source and its efficiency on rocket leaves was evaluated at different processing times through microbial, texture, pH value and colour analyses. A reduction of 0.57 to 1.02 log CFU/g was observed for the total microbial load after processing times ranging from 5 to 20 min, respectively. A CAP processing time of 10 min was considered as optimum, for a sufficient reduction of the microbial load while maintaining colour and texture. The shelf-life of the optimum CAP-processed rocket stored at 2-9 °C was estimated through analysis of specific quality parameters. Pseudomonas spp. growth (higher count of approximately 7.0 log CFU/g) was considered to be the dominant deterioration factor. The shelf-life of the CAP-treated leafy rocket salad was estimated as 116, 84 and 55 h compared to 63, 57 and 37 h for the control samples after storage at 2, 5 and 9 °C, respectively. Industrial relevance Spoilage of fresh-cut vegetables due to microbial growth has a significant economic impact causing food waste by reducing the shelf-life of the products and posing a risk for the public health through possible foodborne illnesses. As a result, there is a real need to seek for alternative methods for preservation of fresh produce. Cold Atmospheric Plasma technology could potentially be applied for microbial load reduction of leafy salads. The proposed protocol along with the device used for Surface Dielectric Barrier Discharge treatment, could be a potential solution for extending the shelf-life of significantly perishable fresh produce.

Imidazole and Methoxybenzylamine Growth Inhibitors Reduce Salmonella Persistence in Tomato Plant Tissues

Article

Jun 2019

Highlights: Small molecules (SMs) 1, 3, 4, and 5 are novel growth inhibitors of Salmonella enterica. These SMs are not toxic to tomato plant tissues including fruits. Combining biocontrol agents and SMs enhanced the control of Salmonella in infected plants. These SMs may be safe bactericides against Salmonella and phytopathogens in produce.

Optimization of Process Variables for Retention of Functional Properties of Bitter Melon (Momordica Charantia L.) and its Shelf-Life Extension

Article

Full-text available

Apr 2019

This study was carried out to investigate the effect of sodium hypochlorite (NaClO), hydrogen peroxide (H2O2) and soaking time on vitamin C, carotenoid, antioxidant activity and total phenolic content for optimizing the pre - treatment for minimal processing of bitter melon slices and to evaluate its shelf life at different storage conditions. Fresh - cut bitter melon slices were given post-cutting treatment of wash solution containing NaClO (25 - 500ppm) and H2O2 (1 - 5%) solution for different time intervals (10 - 120 minutes). The treated samples were analyzed for Vitamin C content, carotenoid, DPPH inhibition activity, ABTS inhibition activity and total phenolic content (TPC) using Central Composite Rotatable Design (CCRD). The optimum condition for soaking achieved by CCRD was NaClO (25 ppm), H2O2 (1 %) and soaking time (56.32 min). The minimally processed bitter melon at optimized wash water treatment was packed in LDPE pouch of 0.1 mm thickness and were evaluated for shelf-life under modified atmospheric packaging, MAP 1 (5 % O2, 25 % CO2 & 70 % N2) and MAP 2 (10 % O2, 20 % CO2 & 70 % N2) stored at temperature of 5, 20 and 35 °C, respectively. Based on microbiological, colour and textural analysis, MAP 1 was found to be better compared to MAP 2 and the shelf - life of fresh - cut bitter melon slices was prolonged up to twenty-eight days of storage.

Effects of Package Atmosphere and Storage Conditions on Minimizing Risk of Escherichia coli O157:H7 in Packaged Fresh Baby Spinach

Article

Full-text available

May 2019

Packaged fresh spinach has been associated with outbreaks of illness caused by Escherichia coli O157:H7. The purpose of this study was to assess the behavior of E. coli O157:H7 in packaged baby spinach in response to storage conditions of temperature and package atmosphere and including effects of inoculation level, spinach leaf damage (cut leaves), internalized or leaf surface contamination, exposure to hypochlorite sanitizer, and package size. Behavior of E. coli O157:H7 inoculated at 2 and 4 log CFU/g on spinach packaged in polymer bags composed of a two-layer laminate (polypropylene and polyethylene) and stored under atmospheres of 20% O2–3% CO2 and 0% O2–15% CO2 (aerobic and anaerobic, respectively) was assessed at 5, 7, 12, and 15°C for up to 14 days. Growth kinetics were calculated using DMFit software. Temperature decreases progressively diminished growth or survival of the pathogen, and an aerobic package atmosphere resulted in longer lag times (4 to 6 days) and lower population levels (0.2 to 1.4 log CFU/g) compared with the anaerobic atmosphere at 15°C. Internalized contamination, leaf cuts, or exposure to 100 ppm of hypochlorite did not result in changes in pathogen behavior compared with controls; however, a growth minimization trend consisting of longer lag times and lower population levels was repeatedly observed in the aerobic compared with the anaerobic package atmospheres. In contrast, growth of indigenous mesophiles and Enterobacteriaceae was unaffected by package atmosphere. Spinach stored at 5 to 7°C in two sizes (5 and 16 oz) of polyethylene terephthalate clamshell packages with ambient air atmospheres was more likely to progress to lower-oxygen conditions in 16-oz compared with 5-oz packages after 7 days of storage (P < 0.05). Practices to maintain aerobic conditions within the package, as well as storage of the package at low temperature, are ways to limit growth of E. coli O157:H7 in packaged spinach. HIGHLIGHTS Cold aerobic conditions limited survival of E. coli O157:H7 in packaged spinach. Low-oxygen atmosphere increased pathogen risk in temperature-abused packages. Internalization, leaf cuts, and hypochlorite stress did not increase pathogen risk. Large spinach packages trended toward lower-oxygen conditions more than small packages. Maintaining cold aerobic conditions can limit pathogen risk in packaged spinach.

Trends in Minimal Processing of Lettuce

Article

May 2018

Lettuce is an expanding salad vegetable for supermarket in India and abroad. It has been emerged as a valued salad alternative in minimally processed food products. Minimal processing gives an additional value to lettuce in terms of convenience and time saving. Mechanical damage to the cells during processing, however, is a major limitation to shelf life of minimally processed lettuce which enhances the microbial growth, enzymatic browning and moisture loss. Different minimal processing techniques such as use of post harvest chemicals, irradiations and modified atmosphere packagings (MAP) have been employed for different category of lettuce. These techniques can be adopted either individually or in combination which extends the shelf life of the products through suppression of respiration, ripening and subsequent senescence and microbial activity. MAP inhibits the ethylene induced effects, balances the O2 and CO2 concentrations and reduces the moisture loss due to the moisture barrier properties of the packaging. This review paper aims to supply information about different approaches being employed to extend shelf-life and quality of minimally processed lettuce. A brief description of the MAP technology is also given.

Effectiveness of different antimicrobial washes combined with freezing against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes inoculated on blueberries

Article

Feb 2018

To ensure the safety of produce, including blueberries, elimination of potential pathogens is critical. This study evaluated the efficacy of antimicrobial washes when coupled with frozen storage against Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes on wild blueberries. Inoculated blueberries were sprayed with antimicrobial solutions at different concentrations for various contact times (chlorine dioxide -2.5, 5, 10, and 15 ppm for 10 s, 1, 5, and 10 min; chlorine -100, 150, and 200 ppm for 10s, 1, 5, and 10 min; lactic acid 1 and 2% for 5, 10 and 20 min) and following treatment, stored at −12 °C for 1 week. Compared to antimicrobial washing alone, the additional freezing significantly reduced pathogens (P < 0.05). Concentrations of all three antimicrobials combined with freezing reduced L. monocytogenes to undetectable levels (detection limit < 1 log CFU/g). The greatest reduction of E. coli O157:H7 (4.4 log CFU/g) and Salmonella (5.4 log CFU/g) was achieved by 2% lactic acid or 200 ppm Cl2 followed with frozen storage. These antimicrobials maintained the visual quality of blueberries and did not leave detectable residues. In conclusion, antimicrobial washes, when combined with frozen storage, effectively reduce the risk of pathogen contamination on blueberries.

Postharvest Quality and Safety of Fresh-Cut Vegetables

Chapter

May 2017

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.

Combination treatment of ohmic heating with various essential oil components for inactivation of food-borne pathogens in buffered peptone water and salsa

Article

Apr 2017
FOOD CONTROL

Consumer preference for minimally processed foods has steadily increased for several years, while foodborne outbreaks from under-processed foods continue to be reported worldwide. We investigated the combination effect of ohmic heating with various essential oil components for inactivation of foodborne pathogens in buffered peptone water and salsa. We choose carvone, eugenol, thymol, and citral to combine with ohmic heating, which are registered for use as flavorings in foodstuffs. Combination treatment of ohmic heating with citral showed the most synergistic bactericidal effect against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in buffered peptone water followed by thymol, eugenol, and carvone. When enumerated on selective media, the reductions were 4.8, 5.7, and 4.3 log CFU/ml for E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. Cell membrane destruction by combination treatment and the loss of cell membrane potential by essential oil components were proposed as the bactericidal mechanism. When applied in salsa, inactivation of bacterial pathogens was the greatest with the ohmic and thymol combination treatment followed by citral, eugenol, and carvone. A synergistic virucidal effect was observed for MS -2 bacteriophage, which was used as a norovirus surrogate. Color (b* values) of salsa were improved by combination treatment of ohmic heating and thymol compared to ohmic treated samples. Therefore, the combination treatment of ohmic heating and thymol could be used effectively to pasteurize salsa.

35. NOVEL APPROACH TO DECONTAMINATE FRUITS AND VEGETABLES: COMBINED TREATMENT OF PULSED LIGHT AND PHOTOSENSITIZATION

Conference Paper

Jan 2014

Taking into account that in post-modern society the consumption of ready to eat meals is increasing all over the world, development of novel, more effective non-thermal technologies to increase food microbial control and reduce the risk of foodborne disease outbreaks becomes issue with global dimension. This study is concerned with the development of novel approach to decontaminate fruits and vegetables from pathogenic and harmful microorganisms. To decontaminate surface of vegetables from inoculated pathogen in non-thermal conditions 5.4 J cm-2 broad spectrum UV (which UV light? A, B or C?) light dose was used and 1.3 log inactivation was achieved. For photosensitization experiments the vegetables inoculated with pathogen were submerged in chlorophyll salt solution (1.5×10-4 or 5×10-3 M) for 5 min and afterwards illuminated with 20 mW cm-2 (λ=400 nm) light up to the total dose 36 J cm-2. Inactivation of 2.4 log was achieved in this case. Combined treatment of photosensitization and pulsed light reduced the level of inoculated pathogen by more than 4 log, the natural contamination (mesophyls)-by 3.8 log. No effects on inactivation of antioxidant enzymes were detected. Moreover, the significant increase of shelf-life of treated vegetables was observed. In conclusion, fast and effective non-thermal technology might be developed for decontamination of fruits and vegetables for freshly cut or ready to eat meals.

Modified atmosphere packaging as a method to extend postharvest life of tulip flowers

Article

Mar 2017

Tulip is one of the most important cut flowers in the world market and abscission of the tepals is this species’ most common symptom during vase life. To prevent these symptoms and extend postharvest life, passive and active modified atmosphere packaging (MAP) was applied at 0°C. Respiratory rate (CO2 Kg⁻¹h⁻¹), ethylene production (µL kg⁻¹h⁻¹) and concentration of CO2 and O2 (%) inside the packaging were evaluated during storage, while fresh weight loss (FWL) (%) and vase life (days) were assessed. Flowers stored using MAP performed significantly better than conventional packaging. A lower FWL (only up to 0.3%) was observed on MAP while FWL was as high as 18 to 21% for conventional packaging after 20 and 31 days, respectively. Vase life was 5.7 and 6.0 days for active and passive MAP, respectively compared to 3.3 days for conventional packing. Thus, MAP successfully extended postharvest life of tulip flowers.

PCR Assay for Detection of Staphylococcus aureus in Fresh Lettuce (Lactuca sativa)

Chapter

Full-text available

Mar 2017

Effect of alternatives to chlorine washing for sanitizing fresh coriander

Article

Full-text available

Jan 2017

Fresh coriander leaves are highly perishable in nature and their sensory quality and nutritional value decreases without proper processing or preservation. In the present study, three aqueous solutions of sodium hypochlorite (SH, 100 mg/L), chlorine dioxide (CD, 10 mg/L), and sodium butyl p-hydroxybenzoate (SBPH, 12 mg/L), and tap water, were used to treat fresh coriander for 15 min. The treated samples were packed in PVC boxes with ambient air under packaged under passive modified atmosphere packaging conditions and stored at 4 °C for 10 days. Effects of washing treatments on color, total chlorophyll contents, ascorbic acid contents, total contents of phenolic compounds, and total aerobic bacterial counts (APC) were investigated. CD treatment has the least detrimental effects on color, total chlorophyll contents and ascorbic acid contents of fresh coriander, followed by SH treatment. In addition, CD treatment showed a greater reduction in APC and maintained the microbial load at lower levels than other treatments during the 10-day storage period.

Application of Modified Atmosphere Packaging as a safety approach to fresh-cut fruits and vegetables – A review

Article

Jul 2015
TRENDS FOOD SCI TECH

This review provides an overview of the effect of modified atmosphere packaging (MAP) on the survival and growth of foodborne pathogens on fresh-cut fruits and vegetables. Substantial technological advances have been made in this area, mainly in improving the quality and shelf-life of minimally processed products. Nevertheless, attention must be paid on the survival and growth of pathogenic microorganisms that may be present in fruits and vegetables. Modified atmosphere packaging (MAP) in combination with refrigeration temperatures could be used as a mild preservation technique for safety of minimally processed fruits and vegetables. However, the effect of MAP on microorganisms can vary, depending mainly on the storage conditions and the type of packaged product.

Biopreservative methods to control the growth of foodborne pathogens on fresh-cut lettuce

Article

Jul 2015

Fruits and vegetables can become contaminated by foodborne pathogens such as Escherichia coli O157:H7, Salmonella and Listeria monocytogenes, and it has been demonstrated that current industrial sanitizing treatments do not eliminate the pathogens when present. Chemical control is widely used, but biological control appears to be a better solution, mainly using the native microbiota present on fresh produce. The first objective of this study was to isolate native microbiota from whole and fresh-cut produce and to determine whether these bacteria were antagonistic toward foodborne pathogens. A total of 112 putative antagonist isolates were screened for their ability to inhibit the growth of Salmonella enterica on lettuce disks. Five different genera reduced S. enterica growth more than 1-log unit at 20°C at the end of 3days. When tested against L. monocytogenes 230/3, only Pseudomonas sp. strain M309 (M309) was able to reduce pathogen counts by more than 1-log unit. Therefore, M309 strain was selected to be tested on lettuce disks at 10°C against S. enterica, E. coli O157:H7 and L. monocytogenes. M309 strain was only able to reduce S. enterica and E. coli O157:H7 populations. The second objective was to test different biopreservative methods including M309 strain, Pseudomonas graminis CPA-7 (CPA-7), bacteriophages (Listex P100 and Salmonelex) and nisin at conditions simulating commercial applications against Salmonella and L. monocytogenes on fresh-cut lettuce. The addition of the biopreservative agents did not result in a significant reduction of Salmonella population. However, CPA-7 strain together with nisin reduced L. monocytogenes numbers after 6days of storage at 10°C. The cocktail of Salmonella and L. monocytogenes was not markedly inactivated by their respective bacteriophage solutions. This study highlighted the potential of biocontrol, but the combination with other technologies may be required to improve their application on fresh-cut lettuce.

Sanitizantes emergentes: Una alternativa en la postcosecha de la rúcula

Article

Full-text available

Jun 2015

The aim of this work was to evaluate the effect of chlorine dioxide (3 and 5 mg L-1; ClO2 3 and ClO2 5), peroxide hydrogen (30 and 50 mg L-1; H2O2 30 and H2O2 50) and UV-C radiation (4 and 5 KJ m-2; UV 4 and UV 5) on the respiration rate, color and microbiological load of arugula leaves (Eruca vesicaria), stored eight days under a passive modified atmosphere at 5 °C; and to compare them with sodium hypoclorite 100 mg L-1; (NaClO 100). After the harvest, the leaves of arugula were transported from the field and stored for 24 h in a chamber at 5°C. The processing was carried out at 8 °C, where the leaves were washed by immersion for 3 min in potable water, before being subjected to different treatments. The microbiological quality was clearly influenced by the sanitizers evaluated. ClO2 5 and H2O2 50 decreased the enterobacteria counts in 1.3 log CFU g-1 compared to the raw material, while NaClO, ClO2 5 and H2O2 50 were the most effective delaying the aerobic mesophilic bacteria, decreasing the counting between 1.0 and 1.4 log CFU g-1. Unlike NaClO, ClO2 also reduced the load of psychrophile microcoorganisms. All treatments preserved the color of the leaves. These results suggest that ClO2 and H2O2 can be used as an alternative to NaClO in the postharvest washing of arugula leaves considering microbiological quality and green color during refrigerated storage.

Novel techniques for the in situ detection of bacteria on salad leaf surfaces

Article

Sep 2009

Jennifer Warner

Bacteria such as Escherichia coli and Salmonella are capable of causing gastrointestinal illness if ingested with food. There is an urgent need within the food processing industry to improve the efficiency of both the sanitising processes used on fresh produce and the microbiological methods used to ensure its safety. The aims of this study were to develop novel microscopic methods to detect and quantify both indigenous leaf bacteria and viable human pathogens on salad leaves, without the need for recovery and culture, which may reduce the accuracy of quantification. The methods developed could then be used to quantify the number of indigenous and inoculated bacteria in situ on salad leaves as well as to identify factors affecting the quantity and spatial patterning of attachment. In addition, the efficacy of chemical biocides for the reduction of viable Salmonella on salad leaves was considered. Episcopic Differential Interference Contrast (EDIC) microscopy coupled with epifluorescence was used to rapidly and non-destructively view the natural microflora in situ on spinach leaves. Salmonella enterica serovar Thompson was inoculated onto spinach leaves in order to observe spatial and temporal patterning of colonisation under differing conditions. Salmonella enterica serovar Typhimurium mutants defective in curli fimbriae production were used to assess the role of curli in attachment to abiotic surfaces and leaves. Viability determination of potential viable but non-culturable (VNC), sub-lethally stressed cells was performed to assess the effect of chemical wash treatments on Salmonella attached to fresh spinach. The results obtained indicate that salad leaves are densely populated with naturally occurring bacteria; these are found predominantly in the margins between leaf epidermal cells as well as around leaf veins and stomata. Cells were present in complex three-dimensional aggregations, suggesting the presence of biofilms. Curli fimbriae were shown to be key in the attachment of Salmonella typhimurium to polystyrene but not to leaf surfaces. When Salmonella thompson was inoculated onto spinach leaves and then subjected to chemical washing in chlorine or Citrox, neither chemical was an effective biocide against the pathogen. Under-reporting of viable cell numbers by plate counting methods indicated that chlorine induced a viable but nonculturable (VNC) state amongst Salmonella. These findings have important implications for the sanitisation of salads; both stomatal penetration and the formation of biofilms could protect enteric bacteria on leaves from chemical and mechanical disinfection strategies. If human pathogens are able to spread to salad leaves from contaminated soil, irrigation water or directly from animal faeces, and actively penetrate the interior of the leaves, then the microbiological safety of ready-to-eat salads cannot be guaranteed. This study also suggests that current methods for detection of pathogenic bacteria in foods following processing may be under-reporting the threat to consumers due to the induction of the VNC state amongst pathogenic bacteria.

Reduction of Salmonella enterica on the surface of eggshells by sequential treatment with aqueous chlorine dioxide and drying

Article

Jun 2015

The synergistic effects of sequential treatments with chlorine dioxide (ClO2) and drying in killing Salmonella enterica on the surface of chicken eggshells were investigated. Initial experiments were focused on comparing lethalities of sodium hypochlorite (NaOCl) and ClO2. Eggs surface-inoculated with S. enterica in chicken feces as a carrier were immersed in water, NaOCl (50 or 200μg/mL), or ClO2 (50 or 200μg/mL) for 1 or 5min. For 1-min treatments, lethal activities of sanitizers were not significantly different (P>0.05). However, after treatment with ClO2 for 5min, reductions of S. enterica were significantly greater (P≤0.05) than reductions after treatment with water or NaOCl. The effect of treatment of eggs with ClO2 or NaOCl, followed by drying at 43% relative humidity and 25°C for 24 and 48h, were determined. Populations of S. enterica decreased during drying, regardless of the type of sanitizer treatment. ClO2 treatment, compared to water or NaOCl treatments, resulted in additional reductions of ca. >1.3logCFU/egg during drying. This indicates that sequential treatments with ClO2 and drying induced synergistic lethal effects against S. enterica on the surface of eggshells. These observations will be useful when selecting a sanitizer to control S. enterica on the surface of eggshells and designing an effective egg sanitization system exploiting the synergistic lethal effects of sanitizer and drying. Copyright © 2015 Elsevier B.V. All rights reserved.

Minimal Processing

Chapter

Feb 2012

The minimal processing to which minimally processed fruits and vegetables (MPFV) are subjected makes products highly perishable, requiring refrigerated conditions during storage to guarantee a reasonable shelf life. The processing steps included in minimal processing steps such as peeling or cutting remove the natural protection of fruits and vegetables, promoting microbial growth as well as physical and physiological changes which reduce both the quality and shelf life of the product. Additionally, the processing steps included in the minimal processing can represent a source of spoilage and pathogenic contamination. In fact, one of the major concerns of MPFV is that none of the steps included in the processing chain will guarantee the inactivation of pathogenic bacteria. Unless numerous studies have been carried out to evaluate the capacity of different sanitizing agents or disinfection techniques for inactivating pathogenic bacteria, their efficacy is still much reduced. Therefore, prevention is the only way to avoid contamination of the product. On the other hand, the optimization of the processing steps to minimize the negative consequences of wounding in MPFV will increase shelf life and maintain the appearance and the nutritional and flavor quality of these products.

In-package cold plasma treatment for microbial inactivation in plastic-pouch packaged steamed rice cakes

Article

Mar 2023
INT J FOOD MICROBIOL

In-package atmospheric cold plasma (ICP) treatment was investigated as a method to inactivate microorganisms in Korean steamed rice cakes (SRCs) packaged in plastic pouches. The effect against Escherichia coli O157:H7 increased with increasing ICP treatment power and time and using nylon-containing pouches. Moreover, E. coli O157:H7 growth was effectively inhibited at 4 and 25 °C when SRCs were in a pouch filled with an O2-CO2 (70 % and 30 %) gas. Under optimal treatment power (30 W), treatment time (4 min), and headspace-to-SRC volume ratio (7:1) conditions, ICP effectively inactivated E. coli O157:H7, Bacillus cereus spores, Penicillium chrysogenum, and indigenous aerobic bacteria, as well as yeast and molds in SRCs packaged with air in the nylon/low density polyethylene pouch by 2.2 ± 0.2 log CFU/g, 1.4 ± 0.2 log spores/g, 2.2 ± 0.3 log spores/g, 1.1 ± 0.2 log CFU/g, and 1.0 ± 0.1 log CFU/g, respectively. Furthermore, post-treatment storage was effective in preventing the growth of E. coli O157:H7 in SRCs at 4 °C and 25 °C when the pouch was filled with N2-CO2 (50 % and 50 %) or O2-CO2 (70 % and 30 %). Collectively, these findings indicate that ICP treatment effectively decontaminates SRCs and represents a potential non-thermal microbial decontamination technology for SRCs in pouch packaging.

Combined effects of NaClO, calcium chloride dipping and MA packaging on shelf life of fresh-cut strawberries

Article

Aug 2021

Efecto de atmósferas modificadas activas y sanitizantes alternativos al cloro sobre la calidad microbiológica y funcional en hojas de rúcula (Eruca vesicaria)

Thesis

Full-text available

Aug 2011

Carlos Inestroza-Lizardo

This work aimed to study the effect of a high concentration of He, Ar, O2, N2 and N2O on the microbiological and sensory quality of rocket leaves preserved for 11 days at 5 °C. After the harvest, the samples were transported from the field and stored for 24 h at 5 °C. The processing was carried out at a temperature of 8 °C, where the leaves were immersed for 3 min in potable water and then in a NaClO solution (100 mg L-1) for another 3 min. The samples were centrifuged in order to eliminate the excess of water and packed in plastic bags (O2 permeability: 3084 mL m2 d-1). Prior to bag sealing, the gases previously mentioned were injected until the O2 level was 9-10%. On the other hand, when O2 was injected, the concentration level reached 80-90%. At day 4 of storage, the aerobic mesophilic bacteria counting were lower than 2,3 log CFU g-1, for He and N2, compared to control. These values are inside the limits established by Chilean legislation, even for 7 days. The another treatments showed differences in about 1,2-2,0 log CFU g-1. On the same way, the enterobacteria counting for N2O, He and N2 treatments were 3,1, 3,8 and 3,4 log CFU g-1 respectively during the day 11, while the control had levels of 5,6 log CFU g-1. According to the sensory analysis, all the treatments were considered acceptable and different from the control at day 11, which experienced a decreasing in the appearance. During the experiment, no differences were found in colour for all treatments. These results suggest the use of Ar, He, N2 and O2 as highly recommended. In addition, the use of low gases permeability in plastic bags is highly recommended in order to retain gases for a longer time and thus increase the effect on rocket leaves.

CA/MA requirements for spoilage microorganisms and human pathogens

Chapter

Jan 2020

Hidemi Izumi

Quantitative Transfer and Sanitizer Inactivation of Salmonella during Simulated Commercial Dicing and Conveying of Tomatoes

Article

Jul 2019
FOOD CONTROL

Diced tomatoes have been linked to outbreaks of salmonellosis in the United States. Compared to slicing, commercial production of diced tomatoes is more complex and includes mechanical dicing as well as washing, dewatering, conveying, and packing. Consequently, this study aimed to 1) quantify Salmonella transfer during pilot-scale dicing of tomatoes, 2) assess the efficacy of three sanitizer treatments against Salmonella during flume tank washing, and 3) assess the efficacy of four sanitizers against Salmonella during conveyance of diced tomatoes. One 0.9 kg batch of Salmonella Typhimurium LT2-inoculated Roma tomatoes (∼5 log CFU/g) was mechanically diced, followed by ten batches of uninoculated tomatoes. All uninoculated tomatoes yielded Salmonella with populations decreasing from 3.3 to 1.1 log CFU/g during dicing. Flume tank washing in sanitizer-free water or water containing 80 ppm of peroxyacetic acid, mixed peracid, or total chlorine decreased Salmonella populations in diced tomatoes 1.3 ± 0.2, 2.3 ± 0.4, 2.35 ± 0.4, and 2.4 ± 0.1 log CFU/g, respectively. After processing, Salmonella populations in flume water containing a sanitizer were always below the limit of detection (−1.0 log CFU/ml) and were significantly lower (P ≤ 0.05) than for the sanitizer-free control (1.5 ± 0.3 log CFU/ml). When the same three sanitizer treatments as well as electrolyzed water (80 ppm chlorine) were applied to smooth and interlocking belts on a dual track conveyor, Salmonella reductions were greater using mixed peracid (6.49 and 6.76 log) and peroxyacetic acid (5.95 and 6.10 log) as compared to chlorine (3.72 and 5.70 log) and electrolyzed water (3.50 and 4.53 log), respectively. All four sanitizer treatments were more effective than water alone in reducing Salmonella on conveyor belt surfaces. These findings should help provide some practical guidelines for the industry and aide in the development of improved risk assessments.

Resistance of Escherichia coli O157:H7 ATCC 35150 to ohmic heating as influenced by growth temperature and sodium chloride concentration in salsa

Article

Apr 2019
FOOD CONTROL

Salsa is a liquid-solid food containing jalapeño and serrano peppers, which result in multistate outbreak in 2008. Storage temperature and sodium chloride (NaCl) concentration of salsa vary depending on the climate, season, and type of product. In this regard, effect of growth conditions, namely, low temperature (15 °C) or NaCl concentration (4.5%) on the resistance of Escherichia coli O157:H7 ATCC 35150 to ohmic heating was identified in this study. Cells of E. coli O157:H7 ATCC 35150 grown under different growth conditions was inoculated into prepared salsa sample, and then subjected to ohmic heating. Mechanisms of resistance acquisition were identified by transcriptional responses, membrane fatty acid changes and confirmed with propidium iodide (PI) uptake values. Resistance of the pathogen to ohmic heating decreased when growth temperature decreased from 37 °C to 15 °C while increased resistance was observed for this pathogen when grown with 4.5% NaCl. Several heat stress related genes such as dnaK, rpoH, grpE, groES, htpG, and htpX were up-regulated (≥5 fold change) as growth temperature decreasedwhile groEL, dnaK, rpoH were up-regulated when grown with high NaCl concentration in the present study. The ratio of unsaturated fatty acids (USFA) to saturated fatty acids (SFA) of pathogen increased slightly (+0.16) or significantly (+0.79) with increasing NaCl concentration or decreasing temperature, respectively. These results indicate that the cell membrane of the pathogen grown at low temperature was more susceptible to heat than when grown under optimal conditions or high NaCl concentration. Cell membrane damage measured by PI uptake values of the pathogen grown with high NaCl concentration were not significantly different from those of the control (p > 0.05), while the values were significantly higher for the pathogen grown at low temperature and subjected to ohmic heating (p < 0.05). Based on these results we suggest that resistance of the pathogen grown at low temperature to ohmic heating decreased because of dominant cell membrane damage compared to induced heat stress related genes. The cell membrane damage was dominant by means of an increased ratio of USFA to SFA. On the other hand, pathogen resistance increased when grown in medium of high NaCl concentration because of induced heat stress related genes.

Synergistic effect of ohmic heating and UV-C irradiation for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in buffered peptone water and tomato juice

Article

Mar 2019
FOOD CONTROL

Hurdle technology, in which preservation techniques are combined, has been of interest to scientists aiming to ensure microbiological food safety. We investigated the synergistic effect of UV-C irradiation and ohmic heating on the inactivation of foodborne pathogens. UV-C irradiation and ohmic heating were applied to buffered peptone water and tomato juice inoculated with pathogens simultaneously or sequentially. A synergistic bactericidal effect of the simultaneous treatment was observed against Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes. For example, the reductions (log CFU/ml) in E. coli O157:H7 by UV-C irradiation, ohmic heating and simultaneous treatment in tomato juice were 0.48, 1.84 and 3.83, respectively. Additive effect was observed for cell membrane damage and lipid oxidation values with the simultaneous treatment Therefore, the proposed synergistic bactericidal mechanism by the simultaneous treatment consists of an acceleration of lipid oxidation, which results in an additive effect on cell membrane pore formation. Sequential treatment of UV-C irradiation after ohmic heating showed the least antibacterial effect in buffered peptone water. On the other hand, the reductions levels of all three pathogens in tomato juice were not significantly different between the two treatments regardless of the sequence. The color and lycopene content of tomato juice were not significantly deteriorated by either ohmic heating or the simultaneous treatment. Therefore, the combination treatment of UV-C irradiation and ohmic heating including simultaneous and sequential treatments, and regardless of treatment sequence, can be used as an effective hurdle technology ensuring microbiological safety in juice products.

Inactivation of Escherichia coli O157:H7, Salmonella typhimurium , and Listeria monocytogenes on cherry tomatoes and oranges by superheated steam

Article

May 2018
FOOD RES INT

This study was performed to compare the effectiveness of saturated steam and superheated steam for the inactivation of Escherichia coli O157:H7, Salmonella typhimurium, and Listeria monocytogenes on the surface of cherry tomatoes and oranges. It also determined the effect of the steam processes on the color, texture, Vitamin C content, and antioxidant capacity and changes in these parameters during chilled storage. Cherry tomatoes and oranges inoculated with the three foodborne pathogens were treated with saturated steam at 100 °C and superheated steam at 125, 150, 175, and 200 °C for various time intervals. After the cherry tomatoes and oranges were exposed to superheated steam at 200 °C for 3 or 20 s, all tested pathogens were reduced to below the detection limit (1 or 1.7 log, respectively) without significant changes in color, texture, vitamin C content, and antioxidant capacity (P >.05) at 4 °C for up to 9 days. Our results suggest that superheated steam treatment can be effective at decreasing pathogen populations when compared to saturated steam, without significant quality deterioration, and thus, this technique demonstrates great potential to improve the microbial safety of fresh produce.

Microbial Safety of Fresh and Processed Vegetables

Chapter

Feb 2018

Jaheon Koo

This chapter shows outbreaks and illnesses associated with fresh produce 2002-2011. Pathogenic microorganisms causing outbreaks can be found on or in fresh produce and are found throughout the natural environment. Microbial contamination of fresh produce can occur at any point along the farm-to-table continuum, including during growing, harvesting, processing, storing, shipping, or final preparation. To reduce potential contamination, the Food and Drug Administration (FDA) has published “Guidance for Industry: Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables”. This guidance provides recommendations for growers, packers, and shippers to use good agricultural practices (GAPs) and good manufacturing practices (GMPs) in preventing or minimizing microbial food safety hazards in fresh produce. Thermal processing is the most extensively used method of food preservation for thousands of years to destroy microorganisms and to extend its shelf-life. There are various degrees of thermal processing: sterilization; commercially sterile; pasteurization; and blanching.

Green Leafy Vegetables

Chapter

Feb 2018

This chapter reviews nutritional composition, harvesting, storage, packing, processing of spinach and lettuce. Spinach is a rich source of calcium, magnesium, phosphorus, potassium, and zinc. Flavonoids found in spinach act as antioxidants that may provide protection against oxidative stress. Spinach consumption is associated with decreased risk of age-related macular degeneration (AMD). Spinach is consumed as fresh or processed into different forms, including frozen, canned, or dried. Lettuce is the most popular salad vegetable and is usually eaten raw. Lettuce contains bioactive compounds, including vitamins, carotenoids, flavonoids, and phenolic acids that can improve nutritional status and benefit health. Lettuce is a good source of dietary fiber. A high fiber diet may reduce the risk of cardiovascular diseases by decreasing low-density lipoprotein (LDL) cholesterol and blood pressure. Consuming lettuce may play a role in blood sugar control for people with diabetes.

Inactivation of Cronobacter malonaticus cells and inhibition of its biofilm formation exposed to hydrogen peroxide stress

Article

Oct 2017
J DAIRY SCI

Presence of Cronobacter malonaticus in powdered infant formula (PIF) poses a high risk to infant and public health. Cronobacter malonaticus has been widely distributed in food and food processing environments, and the true origin of C. malonaticus in PIF is poorly understood. Control and prevention of C. malonaticus is necessary for achieving microbial safety of PIF. However, little information about decontamination of C. malonaticus is available. In this study, effects of hydrogen peroxide on inactivation and morphological changes of C. malonaticus cells were determined. Furthermore, inhibitory effects of H2O2 on biofilm formation in C. malonaticus were also performed. Results indicated that H2O2 could completely inactivate C. malonaticus in sterile water with 0.06% H2O2 for 25 min, 0.08% H2O2 for 15 min, and 0.10% for 10 min, respectively, whereas the survival rates of C. malonaticus in tryptic soy broth medium significantly increased with the same treatment time and concentration of H2O2. In addition, morphological changes of C. malonaticus cells, including cell shrinkage, disruption of cells, cell intercession, and leakage of intercellular material in sterile water after H2O2 treatment, were more predominant than those in tryptic soy broth. Finally, significant reduction in biofilm formation by H2O2 was found using crystal violet staining, scanning electron microscopy, and confocal laser scanning microscopy detection compared with control samples. This is the first report to determine the effects of H2O2 on C. malonaticus cells and biofilm formation. The findings provided valuable information for practical application of H2O2 for decontamination of C. malonaticus in dairy processing.

Review: Comparison of the Effectiveness of Decontaminating Strategies for Fresh Fruits and Vegetables and Related Limitations

Article

Aug 2017

Given that it should be aware of the nutritional benefits, resulting from the consumption of fresh fruits and vegetables consumed raw and/or minimally processed, comparing the efficacy of different individual sanitizing methods against the major food-borne pathogens localized in fresh commodities is of much importance; these products are easily vulnerable to the microbial contamination. In this review, the current propensity of alternative sanitizing methods was introduced, as well as principal elements for deteriorating the cleaning effects were also discussed. Chlorine-based-sanitizers exhibited the microbial reduction of <1.12 log10 CFU/g on fruits and vegetables. Most of aqueous disinfectants showed ≤3.01 log10-redcutions against a variety of microorganisms inoculated on fresh commodities. Similarly, several physical technologies such as hydrostatic pressure and ultraviolet light were effective for reducing surviving bacterial cells could recover and grow rapidly during the whole processing, posing a potential risk of causing food-borne outbreaks associated with the fresh products. The invasion and subsequent localization of the organisms into the inner parts of products, interactions between the microbial cell and food-contacting surfaces, as well as development of biofilms could restrict the antimicrobial activity of the currently used approaches.

Frontiers in Staphylococcus aureus

Book

Mar 2017

Shymaa Enany

35. NOVEL APPROACH TO DECONTAMINATE FRUITS AND VEGETABLES: COMBINED TREATMENT OF PULSED LIGHT AND PHOTOSENSITIZATION

Article

Jan 2011

Materials (Films), Gases, and Machinery (Techniques) for MAP

Chapter

Jun 2012

Minimally Processed Vegetables

Chapter

Jun 2012

Ready-to-eat vegetables: Current problems and potential solutions to reduce microbial risk in the production chain

Article

Nov 2016
LWT-FOOD SCI TECHNOL

The popularity of the consumption of fresh ready-to-eat (RTE) products has increased globally. Simultaneously, the number of outbreaks and cases of foodborne illness associated with the consumption of contaminated fresh produce continues to escalate. Thus, it becomes clear that fresh and fresh-cut vegetables are not processed in ways that effectively eliminate human pathogens. Processing of fresh vegetables involves the application of several unit operations that can provide opportunities for cross-contamination whereby a small proportion of contaminated product may cause the contamination of a large proportion of processed product. Some of these unit operations where contamination and cross-contamination may occur are selection, cleaning, washing, trimming, peeling, cutting and shredding, sanitizing and packing. It is recommended that processors ensure that their suppliers (growers, harvesters, packers and distributors) adopt the principles outlined in the Code of Hygienic Practice for Fresh Fruits and Vegetables. A variety of intervention methods may be used such as mild preservation and/or disinfection techniques to enhance safety of minimally processed produce. Traditional methods of reducing microbial populations on produce involve chemical and physical treatments. This review brings an overview of the main microbial risks faced by the producers and the available alternative strategies to reduce these risks. The information shown gives insights on microbial contamination throughout the processing operations involved in RTE vegetable production.

Effect of modified atmosphere packaging on microbial growth, quality and enzymatic defence of sanitiser washed fresh coriander

Article

Oct 2016
INT J FOOD SCI TECH

Fresh coriander samples were washed in an aqueous chlorine dioxide solution and stored in modified atmosphere packaging (MAP) with air (T0), 4%O2 + 3%CO2 + 93%N2 (T1); 10%O2 + 3%CO2 + 87%N2 (T2); 15%O2 + 3%CO2 + 82%N2 (T3); 20%O2 + 3%CO2 + 77%N2 (T4) at 4 °C for 14 days. After 14 days, the ascorbic acid contents in samples were 24.8 (T3), 22.4 (T4), 19.6 (T0), 18.2 (T2) and 8.8 (T1) mg/100 g; the total phenol contents were 59.9 (T3), 53.8 (T0), 50.1 (T4), 44.8 (T2) and 39.3 (T1) mg gallic acid/100 g; and the total chlorophyll contents were 1.60 (T3), 1.52 (T4), 1.05 (T2), 0.91 (T0) and 0.63 (T1) mg g−1 respectively. T3 treatment resulted in the best colour maintenance, the least bacterial growth, and the highest activities of superoxide dismutase and catalase throughout the storage period as compared to others. The data revealed that the T3 MAP condition in combination of aqueous chlorine dioxide washing significantly (P < 0.05) maintained the quality and extended the shelf life of fresh coriander.

Application of Ultrasound Associated with Chemical Sanitizers for Food Products

Chapter

Jan 2016

Jackline Freitas Brilhante São José

Ultrasound is a form of energy generated by sound waves at frequencies that are too high to be detected by the human ear. Cavitation promotes the removal of dirt and food residues from surfaces and the inactivation of microorganisms. This phenomenon consists of formation, growth, and collapse of bubbles that generate a localized mechanical and chemical energy. There are indications that this technology can be used in the food industry, alone or associated with chemical sanitizers. The chemical and physical energy generated by acoustic cavitation promotes severe damage to the cell wall, resulting in the inactivation of microorganisms. The ultrasound can provide powerful disinfection, but its use for large-scale microbiological decontamination should be further evaluated, and in combination with other technologies, it could even provide excellent results. The use of ultrasound has also been implemented in the disaggregation of biofilms and the inactivation of microorganisms, which can help in the preservation of foods. Studies evaluating the use of ultrasound associated with others treatments, such as organic acids, hydrogen peroxide, and peracetic acid, have been conducted to provide a better understanding of the process and promote its application. Some authors suggest that the combination of ultrasound with other sanitizers can produce a synergistic effect. This chapter will discuss the application of ultrasound associated with chemicals products.

Aqueous chlorine dioxide treatment of horticultural produce: Effects on microbial safety and produce quality - A review

Article

May 2016

Microbial load on fresh fruit and vegetables causes decay and losses after harvest and may lead to foodborne illness in case of contamination with human pathogens on raw consumed produces. Washing with tap water only marginally reduces microorganisms attached to produce surfaces. Chlorine is widely used for decontamination on fresh horticultural produces. However, due to harmful by-products and the questionable efficacy it has become increasingly challenged. During the last 20 years, the interest to study ClO2 treatments as an alternative sanitation agent for industrially prepared fresh produce has largely increased. For a wide range of commodities, the application of gaseous ClO2 has meanwhile been investigated. In addition, since several years, the interest in aqueous ClO2 treatments has further risen because of the better manageability in postharvest processing lines compared to gaseous application. This article critically evaluated the effects of postharvest application of aqueous ClO2, either alone or in combination with other treatments, on microbial loads for various horticultural produces. In laboratory investigations, application of aqueous ClO2 at concentrations between 3 and 100 ppm effectively reduced counts of natural or inoculated microorganisms (bacteria, yeasts and mold) in the range of 1 and 5 log. However, various effects of ClO2 treatments on produce quality have been described. These mainly comprise implication on sensory and visual attributes. In this context, there is increasing focus on the potential impacts of aqueous ClO2 on relevant nutritional components of produces such as organic acids or phenolic substances.

Effects of Washing Treatments with Different Components on Removal of Pesticide Residues and Microorganisms in 'Fuji' Apples

Article

Sep 2008
KOREAN J HORTIC SCI

The study was conducted to investigate the efficiency of different washing treatments which can remove pesticides and microorganism contaminations on apples (Malus domestica). Apples were washed with tap water, chlorinated water, electrolyzed water, ozonated water, and acetic acid solution, respectively as prestorage treatment and then changes in pesticide residue and microorganism activity were estimated. Although there were differences in effect according to the type of the pesticide, washing treatments were more effective than tap water treatments in pesticide removal. Especially, residues of rnyclobutanil was decreased from 0.39 to 010 mg.L-1 after electrolyzed water treatment (removal rate 74.4%). Population levels of total micro-organism were also reduced by chlorinated, electrolyzed and ozonated water, but increased or not affected by acetic acid solution and tap water washings. Chlorinated and electrolyzed (100 mg.L-1) water treatments were markedly reduced populations of total microorganism for 2 weeks at 0 degrees C. The effect of water treatments on quality attributes during storage at 0 degrees C was not significantly different from other water treatments. As a result, if pesticide and microbial reduction, and maintaining quality are taken into account together, the cleaning process using chlorinated and electrolyzed water were the most effective washing treatment methods.

Application of Ultrasound Associated with Chemical Sanitizers for Food Products

Chapter

Jan 2016

Jackline Freitas Brilhante São José

Fruits and Vegetables: Advances in Processing Technologies to Preserve and Enhance the Safety of Fresh and Fresh-Cut Fruits and Vegetables

Article

Full-text available

Dec 2014

The challenge of providing fruits and vegetables free from contamination with human pathogens has led to the development and optimization of a variety of postharvest-processing technologies. This chapter summarizes recent research related to chemical and physical treatments for fresh and fresh-cut produce. The technologies discussed range from optimizations and advances in conventional treatments, such as antimicrobial sanitizers and modified atmosphere packaging, to applications of established nonthermal processes, such as irradiation and ultraviolet light treatment. Novel tools such as cold plasma also are reviewed. Finally, the criteria for successful commercial adoption of new fresh produce processing tools are summarized.

Data

Oct 2015

Effect of abusive storage temperatures on growth and survival of E. coli O157:H7 onleafy salad vegetables in Egypt

Article

Sep 2015
LWT-FOOD SCI TECHNOL

Rowaida Khalil

The objective of this study was to determine the fate of Escherichia coli O157:H7 on damaged leafy green vegetables with greatest national sales in Egypt under abusive storage conditions that match those of retail, food service and consumer home settings. Damaged leaves inoculated with a four-strain cocktail of approximately 105 CFU E. coli O157:H7 per leaf, held at 8, 15, or 22 ± 2 °C (room temperature) for up to 3-4 days, were enumerated periodically for surviving populations of aerobic mesophilic bacteria and E. coli O157:H7. Storage of damaged leaves at 8 °C generated variable outcomes of pathogen populations due to interference of background microorganisms. Significantly (P < 0.05) low numbers of E. coli O157:H7 on damaged spinach were associated with high levels of total phenolics, flavonoids, anti-oxidant activity, and pH increase. At room temperature, damaged leek maintained acceptable visual qualities and moisture content despite the maximum loads of microbial populations. Attention of public health laboratories, and Food Safety Agency in Egypt should be directed to the significant findings of this study for raising consumer awareness, risk assessment and improving safety measures/interventions that remove or limit pathogen growth, should contamination inadvertently occur at any stage of leafy greens production chain.

SpringerBriefs in Food, Health, and Nutrition

Chapter

Sep 2014

The increasing demand for healthier and “safer” foods has led the food industry in pursuit of storage technologies that will serve the primary role of storage life prolongation but with no losses on nutritional value and in the absence of additives. Modified Atmosphere packaging (MAP) is a storage technique that has already proven to be effective in extending the shelf life of the product by reducing respiration rate and preserving all its quality characteristics. Due to many physiological factors that affect the shelf life of minimally processed vegetables (respiration rate, ethylene production, maturation and ripening) the selection of the ideal storage parameters (gas mixture, storage temperature, packaging film, and treatments prior to packaging) of MAP is a challenging procedure and must be planned carefully. This paper critically reviews the applied techniques in all studied vegetables and summarizes the effect of MAP on all quality parameters.

Escherichia coli O157:H7: Epidemiology, Pathogenesis, and Methods for Detection in Food

Article

Full-text available

Jul 1992

Escherichia coli O157:H7 is now recognized as an important human pathogen. Illnesses caused by E. coli O157:H7 infection can range from self-limited, watery diarrhea to life-threatening manifestations such as hemolytic uremic syndrome or thrombotic thrombocytopenic purpura. The mode of transmission is primarily through food; however, person-to-person transmission also has been identified in some day-care center and nursing home outbreaks. Studies to date indicate that cattle are an important reservoir of the organism. Although adhesion to intestinal epithelial cells and verotoxins are considered important virulence factors in the pathogenesis of the organism, more research is are necessary to determine the exact mechanism of pathogenicity. There is need for a rapid diagnostic test for the detection of E. coli O157:H7 in food and in clinical samples. Several useful research reagents have been developed for detecting E. coli O157:H7; however, they must be applied to a procedure that is specific, sensitive, rapid, easy to use, and commercially available so that microbiological laboratories can readily use them. Copyright ©, International Association of Milk, Food and Environmental Sanitarians.

Shelf Stability and Safety of Fresh Produce as Influenced by Sanitation and Disinfection

Article

Full-text available

Oct 1992

Robert Brackett

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.

Microbiological Control of Cucumber Hydrocooling Water with Chlorine Dioxide

Article

Full-text available

May 1995

The time required to cool size 2B (3.43 to 3.75-cm-diameter) pickling cucumbers by a commercial spray-type hydrocooler to less than 9°C was about 18 min at typical initial fruit temperatures of 25 to 29°C. During this period, the fruit was exposed to the recycled water, which reached relatively high populations of bacteria (106 to 107 colony forming unites [CFU]/g total aerobes and 106 to 106 CFU/g total Enterobacteriaceae) during a typical day's operation. These numbers exceeded those present on the unwashed fruit, depending upon the volume of fruit previously cooled. Residual chlorine dioxide at 1.3 ppm was found to optimally control (2 to 6 log-cycles reduction) the numbers of bacteria. At 0.95 ppm chlorine dioxide, the numbers of bacteria in the water were relatively static, while at 2.8 and 5.1 ppm the odor of chlorine dioxide became excessive. The bacterial populations in/on the cucumbers were not greatly influenced by chlorine dioxide, even at 5.1 ppm. Apparently, microorganisms on or in the fruit were protected from the chlorine dioxide. Thus, the use of chlorine dioxide in hydrocooling water of cucumbers seems to be an effective means of controlling microbial build-up in the water, but has little effect upon microorganisms on or in the fruit.

Pathogenic Microorganisms Associated with Fresh Produce

Article

Full-text available

Feb 1996

Larry R. Beuchat

The presence of numerous genera of spoilage bacteria, yeasts and molds, and an occasional pathogen on fresh produce has been recognized for many years. Several outbreaks of human gastroenteritis have been linked to the consumption of contaminated fresh vegetables and, to a lesser extent, fruits. Salads containing raw vegetables have been identified as vehicles of traveler's diarrhea, an illness sometimes experienced by visitors to developing countries. Enterotoxigenic Escherichia coli is the most common cause of this illness. Enterohemorrhagic E. coli, specifically serotype O157:H7, has been implicated as the causative agent in an outbreak of gastroenteritis resulting from the consumption of cantaloupes. Outbreaks of salmonellosis in humans have been attributed to consumption of contaminated tomatoes, mustard cress, bean sprouts, cantaloupe, and watermelon. An onion-associated outbreak of Shigella flexneri gastroenteritis has recently been reported in the United States. Outbreaks of human listeriosis have been epidemiologically linked to the consumption of fresh cabbage and lettuce. Gastrointestinal illness caused by the consumption of raw vegetable seed sprouts contaminated by Bacillus cereus has been documented. The ability of Aeromonas hydrophila and Aeromonas sobria to produce several virulence factors has been documented and their fairly common occurrence in water raises concern over public health risks that may be associated with the consumption of salad vegetables, although their role as agents in foodborne illness has not been fully confirmed. Viruses are not likely to grow on contaminated vegetables and fruits but can survive long enough to cause life-threatening illness in humans. An increased per capita consumption of fresh and lightly processed produce in the United States and other countries, coupled with an increase in importation of produce to these countries from regions where standards for growing and handling produce may be compromised, has resulted in heightened interest in outbreaks of human gastroenteritis that may be attributed to contaminated fresh produce, particularly salad vegetables. Likewise methods of handling, processing, packaging, and distribution of fresh produce on a regional or local scale within countries are receiving attention in terms of identifying and controlling microbiological hazards. Hazard analysis critical control point (HACCP) programs are being developed in an effort to minimize the risk of illness associated with consumption of fresh produce. Examples of pathogenic microorganisms associated with fresh produce as well as procedures that can be used to reduce their incidence at the point of consumption are discussed.

A Swimming-Associated Outbreak of Hemorrhagic Colitis Caused by Escherichia coli O157:H7 and Shigella Sonnei

Article

Full-text available

Sep 1994

In the summer of 1991, simultaneous outbreaks of bloody diarrhea and hemolytic-uremic syndrome caused by Escherichia coli O157:H7 and of bloody diarrhea caused by Shigella sonnei were traced to a lakeside park near Portland, Oregon. We identified cases primarily from routine surveillance reports. In case-control studies, the activities of persons with park-associated E. coli O157:H7 or S. sonnei infections were compared independently with those of three sets of controls. We also evaluated environmental conditions at the park and subtyped the bacterial isolates. We identified 21 persons with park-associated E. coli O157:H7 infections (all of them children; median age, six years) and 38 persons with S. sonnei infections (most of them children). These 59 people had visited the park over a 24-day period. Their illnesses were not associated with food or beverage consumption. All the case patients reported swimming, however, and in case-control studies swimming was strongly associated with both types of infection (P = 0.015 or less). The case patients were more likely than the controls to report having swallowed lake water, and they had spent more time in the lake. Numbers of enterococci indicative of substantial fecal contamination (geometric mean, > 50 per deciliter) were detected in the swimming area during some but not all of the outbreak period. Park-associated E. coli O157:H7 isolates were identical by pulsed-field gel electrophoresis and were distinguishable from other isolates in the Portland area. Lake water that was fecally contaminated by bathers was the most likely vehicle for the transmission of both the E. coli O157:H7 and the S. sonnei infections. The unusually prolonged outbreak suggests both the survival of these enteric organisms in lake water and a low infectious dose.

Acid resistence in enteric baceria

Article

Full-text available

Feb 1993

Shigella species require a uniquely small inoculum for causing dysentery. One explanation for the low infective dose is that Shigella species are better able to survive the acidic conditions encountered in the stomach than are other enteric pathogens. We have tested Shigella species, Escherichia coli, and Salmonella species for the ability to survive at pH 2.5 for at least 2 h. Most isolates of Shigella and E. coli survived this treatment, whereas none of the Salmonella isolates were able to do so. The ability of Shigella species to survive at low pHs does not require the presence of the large virulence plasmid or growth at 37 degrees C but is strikingly dependent on growth phase. We have also found that Shigella isolates exposed to acid lose the ability to invade epithelial cells.

Comparison of Chemical Treatments to Eliminate Enterohemorrhagic Escherichia coli O157:H7 on Alfalfa Seeds

Article

Full-text available

May 1999

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

Full-text available

Oct 1999
EMERG INFECT DIS

To better quantify the impact of foodborne diseases on health in the United States, we compiled and analyzed information from multiple surveillance systems and other sources. We estimate that foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Known pathogens account for an estimated 14 million illnesses, 60, 000 hospitalizations, and 1,800 deaths. Three pathogens, Salmonella, Listeria, and Toxoplasma, are responsible for 1,500 deaths each year, more than 75% of those caused by known pathogens, while unknown agents account for the remaining 62 million illnesses, 265,000 hospitalizations, and 3,200 deaths. Overall, foodborne diseases appear to cause more illnesses but fewer deaths than previously estimated.

Effects of vegetable type, package atmosphere and storage temperature on growth and survival of Escherichia coli O157:H7 and Listeria monocytogenes

Article

Full-text available

Aug 2001

The survival and growth of Escherichia coli O157:H7 (ATCC 43888 and NCTC 12900) and Listeria monocytogenes (ATCC 19114 and NCTC 11994) during storage (4 and 8 degrees C) on ready-to-use (RTU) packaged vegetables (lettuce, swedes (rutabaga), dry coleslaw mix, soybean sprouts) were studied. The vegetables were sealed within oriented polypropylene packaging film, and modified atmospheres developed in packs during storage due to produce respiration. Survival and growth patterns were dependent on vegetable type, package atmosphere, storage temperature and bacterial strain. Populations of L. monocytogenes and E. coli O157:H7 increased (P<0.05, by 1.5 to 2.5 log cycles, depending on strain) during a 12-day storage period on shredded lettuce (8 degrees C). L. monocytogenes populations also increased (by approximately 1 log cycle) on packaged swedes, did not change significantly (P>0.05) in packages of soybean sprouts and decreased by approximately 1.5 log cycles (P<0.05) on coleslaw mix (8 degrees C). E. coli O157:H7 populations on packaged coleslaw and soybean sprouts increased (by 1.5 to 2.5 log cycles) up to day 5, but declined during subsequent storage (8 degrees C). On packaged swedes (8 degrees C), populations of E. coli O157:H7 strain ATCC 43888 increased (by approximately 1 log cycle) during storage, whereas populations of strain 12900 increased between days 2 and 5, and declined during subsequent storage. Reducing the storage temperature from 8 to 4 degrees C reduced the growth of L. monocytogenes and E. coli O157:H7 on packaged RTU vegetables. However, viable populations remained at the end of the storage period at 4 degrees C.

Inhibition of Salmonella Typhimurium and Listeria monocytogenes in Mung Bean Sprouts by Chemical Treatment

Article

Full-text available

Aug 2002

This study was undertaken to compare the efficacies of chlorous acid (268 ppm), sodium hypochlorite (200 ppm), and lactic acid (2%) in eliminating total mesophilic microorganisms, Salmonella Typhimurium, and Listeria monocytogenes on commercial mung bean sprouts immediately after treatment and during posttreatment refrigerated storage. Treatment with sodium hypochlorite for 10 min did not reduce the total aerobic count. However, treatment with lactic acid and chlorous acid for 10 min initially reduced the total aerobic count by 0.6 and 0.8 log CFU/g, respectively, and maintained the same level or a lower level of the total aerobic count during the storage time. Treatment with chlorous acid reduced Salmonella Typhimurium from 5.0 log to undetectable levels (<0.48 log CFU/g), and the pathogen remained undetectable over a 9-day storage period. Treatment with lactic acid resulted in an initial 3-log reduction and further reduced the number of Salmonella Typhimurium cells to undetectable levels after 3 days. For L. monocytogenes, treatment with chlorous acid resulted in an initial 5-log reduction, and treatment with lactic acid resulted in a 2-log reduction at the beginning and undetectable levels after 9 days. When chemically injured cells were investigated by the selective overlay method, no statistical difference was observed (P < 0.05) between the number of injured cells recovered following treatment with chlorous acid and the number of bacteria counted on selective media, whereas sodium hypochlorite generated more injured cells than the other treatments did. These data suggest that treatment with chlorous acid may be useful in reducing total mesophilic microorganisms, Salmonella Typhimurium, and L. monocytogenes in commercial mung bean sprouts.

A Comparison of Different Chemical Sanitizers for Inactivating Escherichia coli O157:H7 and Listeria monocytogenes in Solution and on Apples, Lettuce, Strawberries, and Cantaloupe

Article

Full-text available

Apr 2004

Ozone (3 ppm), chlorine dioxide (3 and 5 ppm), chlorinated trisodium phosphate (100- and 200-ppm chlorine), and peroxyacetic acid (80 ppm) were assessed for reduction of Escherichia coli O157:H7 and Listeria monocytogenes in an aqueous model system and on inoculated produce. Initially, sanitizer solutions were inoculated to contain approximately 10(6) CFU/ml of either pathogen, after which aliquots were removed at 15-s intervals over a period of 5 min and approximately plated to determine log reduction times. Produce was dip inoculated to contain approximately 10(6) E. coli O157:H7 or L. monocytogenes CFU/g, held overnight, submerged in each sanitizer solution for up to 5 min, and then examined for survivors. In the model system study, both pathogens decreased > 5 log following 2 to 5 min of exposure, with ozone being most effective (15 s), followed by chlorine dioxide (19 to 21 s), chlorinated trisodium phosphate (25 to 27 s), and peroxyacetic acid (70 to 75 s). On produce, ozone and chlorine dioxide (5 ppm) were most effective, reducing populations approximately 5.6 log, with chlorine dioxide (3 ppm) and chlorinated trisodium phosphate (200 ppm chlorine) resulting in maximum reductions of approximately 4.9 log. Peroxyacetic acid was the least effective sanitizer (approximately 4.4-log reductions). After treatment, produce samples were stored at 4 degrees C for 9 days and quantitatively examined for E. coli O157:H7, L. monocytogenes, mesophilic aerobic bacteria, yeasts, and molds. Populations of both pathogens remained relatively unchanged, whereas numbers of mesophilic bacteria increased 2 to 3 log during storage. Final mold and yeast populations were significantly higher than initial counts for chlorine dioxide- and ozone-treated produce. Using the nonextended triangle test, whole apples exposed to chlorinated trisodium phosphate (200 ppm chlorine) and shredded lettuce exposed to peroxyacetic acid were statistically different from the other treated samples.

Efficacy of Sanitizers To Inactivate Escherichia coli O157:H7 on Fresh-Cut Carrot Shreds under Simulated Process Water Conditions

Article

Full-text available

Dec 2004

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.

Epidemiology of Escherichia coli O157:H7 Outbreaks, United States, 1982–2002

Article

Full-text available

Apr 2005
EMERG INFECT DIS

Escherichia coli O157:H7 causes 73,000 illnesses in the United States annually. We reviewed E. coli O157 outbreaks reported to Centers for Disease Control and Prevention (CDC) to better understand the epidemiology of E. coli O157. E. coli O157 outbreaks (>or=2 cases of E. coli O157 infection with a common epidemiologic exposure) reported to CDC from 1982 to 2002 were reviewed. In that period, 49 states reported 350 outbreaks, representing 8,598 cases, 1,493 (17%) hospitalizations, 354 (4%) hemolytic uremic syndrome cases, and 40 (0.5%) deaths. Transmission route for 183 (52%) was foodborne, 74 (21%) unknown, 50 (14%) person-to-person, 31 (9%) waterborne, 11 (3%) animal contact, and 1 (0.3%) laboratory-related. The food vehicle for 75 (41%) foodborne outbreaks was ground beef, and for 38 (21%) outbreaks, produce.

Evaluation of Consumer-Style Cooking Methods for Reduction of Escherichia coli O157:H7 in Ground Beef

Article

Full-text available

Jun 2003

The objective of this study was to evaluate the thermal inactivation of Escherichia coli O157:H7 in ground beef cooked to an internal temperature of 71.1 degrees C (160 degrees F) under conditions simulating consumer-style cooking methods. To compare a double-sided grill (DSG) with a single-sided grill (SSG), two different cooking methods were used for the SSG: for the one-turnover (OT-SSG) method, a patty was turned once when the internal temperature reached 40 degrees C, and for the multiturnover (MT-SSG) method, a patty was turned every 30 s. Patties (100 g, n = 9) inoculated with a five-strain mixture of E. coli O157: H7 at a concentration of 10(7) CFU/g were cooked until all three temperature readings (for two sides and the center) for a patty were 71.1 degrees C. The surviving E. coli O157:H7 cells were enumerated on sorbitol MacConkey (SMAC) agar and on phenol red agar base with 1% sorbitol (SPRAB). The order of the cooking methods with regard to the cooking time required for the patty to reach 71.1 degrees C was as follows: DSG (2.7 min) < MT-SSG (6.6 min) < OT-SSG (10.9 min). The more rapid, higher-temperature cooking method was more effective (P < 0.01) in destroying E. coli O157:H7 in ground beef. E. coli O157:H7 reduction levels were clearly differentiated among treatments as follows: OT-SSG (4.7 log10 CFU/g) < MT-SSG (5.6 log10 CFU/g) < DSG (6.9 log10 CFU/g). Significantly larger numbers of E. coil O157:H7 were observed on SPRAB than on SMAC agar. To confirm the safety of ground beef cooked to 71.1 degrees C, additional patties (100 g, n = 9) inoculated with lower concentrations of E. coli O157:H7 (10(3) to 10(4) CFU/g) were tested. The ground beef cooked by the OT-SSG method resulted in two (22%) of nine samples testing positive after enrichment, whereas no E. coli O157:H7 was found for samples cooked by the MT-SSG and DSG methods. Our findings suggest that consumers should be advised to either cook ground beef patties in a grill that cooks the top and the bottom of the patty at the same time or turn patties frequently (every 30 s) when cooking on a grill that cooks on only one side.

Behavior of Escherichia coli O157:H7 in Leafy Vegetables

Article

Full-text available

Sep 2007

Leafy vegetables, including lettuce and spinach, have been implicated in several outbreaks of foodborne disease caused by Escherichia coli O157:H7, a pathogen of increasing public health significance because of the severity of the gastrointestinal illness and long-term, chronic sequelae that can result from infection. A definitive association between the consumption of leafy vegetables and human disease provides implicit evidence of transfer from animal sources to field crops and retail commodities, including minimally processed or fresh-cut products. Understanding the behavior of E. coli O157:H7 in leafy vegetables during production, after harvest, in storage, during processing, and in packaged fresh-cut products is essential for the development of effective control measures. To this end, previous research on the fate of the species at each step in the production of market-ready leafy vegetables is reviewed in this study. Several critical gaps in knowledge are identified, notably uncertainty about the location of contaminating cells on or in plant tissues, behavior in packaged products stored at low temperatures, and the influence of environmental stresses on growth and infectivity.

Efficacy of Chlorine Dioxide Gas Sachets for Enhancing the Microbiological Quality and Safety of Blueberries

Article

Full-text available

Oct 2007

In response to increasingly stringent microbial specifications being imposed by purchasers of frozen blueberries, chlorine dioxide (ClO2) gas generated by a dry chemical sachet was assessed for inactivation of Listeria monocytogenes, Salmonella spp., and Escherichia coli O157:H7 as well as five yeasts and molds known for blueberry spoilage. Fresh blueberry samples (100 g) were separately inoculated with cocktails of L. monocytogenes, Salmonella, E. coli O157:H7 (three strains each), or yeasts and molds (five strains each) to contain approximately 10(6) CFU/g and exposed to ClO2 (4 mg/liter, 0.16 mg/g) for 12 h in a sealed 20-liter container (99.9% relative humidity) at approximately 22 degrees C. After gassing, 25 g of blueberries was added to 225 ml of neutralizing buffer, pulsified for 1 min, and plated using standard procedures to quantify survivors. This treatment yielded reductions of 3.94, 3.62, 4.25, 3.10, and 3.17 log CFU/g for L. monocytogenes, Salmonella, E. coli O157:H7, yeasts, and molds, respectively. Thereafter, 30 lugs of uninoculated blueberries (approximately 9.1 kg per lug) were stacked on 1.2 by 1.2-m pallets (5 lugs per level x six levels), tarped, and exposed to ClO2 (18 mg/liter, 0.13 mg/g) for 12 h. After gassing, significant (P < 0.05) reductions of 2.33, 1.47, 0.52, 1.63, and 0.48 log CFU/g were seen for mesophilic aerobic bacteria, coliforms, E. coli, yeasts, and molds, respectively, compared with non-gassed controls. No significant differences (P > 0.05) in microbial inactivation were seen between lug levels and, with one exception (mesophilic aerobic bacteria), between the bottom and top surface of individual lugs. Based on these findings, ClO2 sachets may provide a simple, economical, and effective means of enhancing the microbial shelf life and safety of blueberries.

Acid resistance in enteric bacteria

Article

Jan 1993

Determination of Chlorine Dioxide, Chlorine, Chlorite, and Chlorate in Water

Article

Jan 1984
J AM WATER WORKS ASS

This article describes a procedure for either amperometric or potentiometric determination of iodine formed by the oxidation of iodide by chlorine dioxide, chlorine, chlorite, and chlorate. Either phenylarsine oxide or sodium thiosulfate can be used as the titrant. Sample pretreatment and pH adjustment are used to differentiate among the various chlorine species.

Surface disinfection of raw produce

Article

Jan 1992

L.R. Beuchat

Guidance for industry: guide to minimize food safety hazards for fresh-cut fruits and vegetables

Article

Jan 2008

Comparative Growth ofEscherichia coli0157:H7, Spoilage Organisms and Shelf-Life of Shredded Iceberg Lettuce Stored under Modified Atmospheres

Article

Apr 1996
J SCI FOOD AGR

The objective of this work was to compare organoleptic and microbiological spoilage with the survival of Escherichia coli0157:H7 in modified atmosphere (MA) stored shredded lettuce. The rates of growth ofE coli0157:H7, increase in aerobic plate counts (APC g−1), and rates of visual spoilage of shredded lettuce held under air or MA at 13 and 22°C were compared. Samples were inoculated with nalidixic acid-resistantE coli0157:H7 (ATCC 35150) and placed in a chamber which was continuously flushed with gas mixtures of 0/10/90, 3/0/97, 5/30/65, 20/0/80 (O2/CO2/N2, v/v) and held at 13 or 22°C. APC growth was inhibited in 5/30/65 (O2/CO2/N2) at 13°C compared to all other atmospheres which were not significantly different from each other. The growth rates for bothE coli0157:H7 and APC were greatest in air at 22°C. Carbon dioxide concentration had no significant effect on the growth ofE coli0157:H7 at either temperature. The shelf-life of shredded lettuce, as judged by appearance, was extended in atmospheres containing 30% CO2 by approximately 300% compared to air. The APC were similar at the time when the shredded lettuce samples were judged unacceptable regardless of shelf-life. However, the extended shelf-life provided by the MA allowedE coli0157:H7 to grow to higher numbers compared to air-held shredded lettuce.

Vero-cytotoxin producing Escherichia coli O157:H7 in beef burgers linked to an outbreak of diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome in Britain

Article

Nov 1994
LETT APPL MICROBIOL

Vero cytotoxin (VT)-producing Escherichia coli O157 (0157 VTEC) were isolated from a raw beefburger obtained from a retail source linked to a small community outbreak of 0157 VTEC infection in Wales. Strains from the meat and from seven of eight patients belonged to phage type 49 and were indistinguishable by their VT-type, plasmid content and hybridization with DNA of a VT-encoding phage from an 0157 VTEC strain. This first report of the isolation of 0157 VTEC from a beef product in Britain supports the view that there is a bovine reservoir for this organism.

Inactivation of Escherichia coli O157:H7 on surface-uninjured and -injured green pepper (Capsicum annuum L.) by chlorine dioxide gas as demonstrated by confocal laser scanning microscopy

Article

Dec 2000

Cells of Escherichia coli O157:H7 on uninjured and injured surfaces of green pepper were inactivated by 0·15–1·2 mg l−1ClO2gas treatments. A membrane-surface-plating method was used for resuscitation and enumeration of E. coli O157:H7 treated with ClO2. The location and viability ofE. coli O157:H7 on uninjured and injured green pepper surfaces after ClO2gas treatments were visualized using confocal laser scanning microscopy (CLSM). Live and dead cells of E. coli O157:H7 on pepper surfaces were labeled with a fluorescein isothiocyanate-labeled antibody and propidium iodide, respectively. A 7·27 log reduction of E. coli O157:H7 on uninjured green pepper surfaces was obtained with a 0·60 mg l−1ClO2gas treatment for 30 min at 20°C under 90–95% relative humidity. For injured surfaces, a 6·45 log reduction was achieved with a 1·2 mg l−1ClO2gas treatment. Each ClO2gas treatment (0·15–1·2 mg l−1ClO2) for inoculated bacteria on uninjured surfaces showed significantly more reductions (1·23–4·24 log) than for those on injured surfaces (P<0·05). The microphotographs of CLSM showed that bacteria preferentially attached to injured surfaces and those bacteria could be protected from bacterial reduction by the injuries. This study indicates that ClO2gas treatment can be a potential effective method of pathogen reduction for fresh fruits and vegetables.

PH—Postharvest Technology: Modified Atmosphere Storage of Grains Meats Fruits and Vegetables

Article

Jul 2002

Consumer demand for more natural, minimally processed and fresh foods is increasing. Modified atmosphere storage is a well-proven technology for preserving natural quality of food products in addition to extending the storage life. Extensive research has been done in this research area around the globe for many decades. Modified atmosphere storage is one of the most successful preservation techniques suitable for wide varieties of agricultural and food products. Grain farmers are seeing advantage in using this method as strict regulations are enforced on the use of other chemical preservation methods. Success of modified atmosphere storage of grains depends on the airtightness of the grain bins and research is needed to find the techniques to improve the sealability of the existing grain bins. It is widely practiced in the meat industry for preserving primal and sub-primal cuts. Modified atmosphere packaging is also commercially successful for preserving certain fruits and vegetables. With the vast basic and fundamental knowledge available on this subject, the research in this area is taking a new dimension to suit the new consumer trends and demands. There are new interests in applying this technique to the consumer-ready products in the meat industry. This technique can be integrated with active or interactive packaging to improve the control over the package atmosphere to achieve superior product quality and safety. Time–temperature indicators on the packages to show the remaining storage life of the food product would improve food safety and inventory control. In this paper, published research on modified atmosphere storage specifically on grains, meats, fruits and vegetables is critically reviewed and opportunities for future research are explored.

The Epidemiology of Infections Caused by Escherichia coli O157:H7, Other Enterohemorrhagic E. coli, and the Associated Hemolytic Uremic Syndrome

Article

Feb 1991

Development of a selective plating technique for the recovery of Escherichia coli O157:H7 after heat stress

Article

Oct 1995

The use of Sorbitol MacConkey Agar supplemented with 4-methylumbelliferyl beta-D-glucuronide (MSMA), which is commonly used in the isolation of Escherichia coli O157:H7, has been shown to perform poorly when stressed cells of the pathogen are present. The incorporation of a resuscitation period (2 h at 25 degrees C) on Trypticase Soy Agar (TSA) before overlay with MSMA was found to significantly (P < or = 0.01) improve recovery of heat-stressed (52 degrees C/60 min) cells. Maximal recovery was, however, obtained by adding catalase (1000 U) to the TSA before overlaying with MSMA. This recovery protocol was shown not to result in the loss of the major known virulence factors of E. coli O157:H7 (genes encoding eae, VT1 and VT2).

Vero cytotoxin-producing Escherichia coli O157 in beefburgers linked to an outbreak of diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome in Britain

Article

Dec 1994

Vero cytotoxin (VT)-producing Escherichia coli O157 (O157 VTEC) were isolated from a raw beefburger obtained from a retail source linked to a small community outbreak of O157 VTEC infection in Wales. Strains from the meat and from seven of eight patients belonged to phage type 49 and were indistinguishable by their VT-type, plasmid content and hybridization with DNA of a VT-encoding phage from an O157 VTEC strain. This first report of the isolation of O157 VTEC from a beef product in Britain supports the view that there is a bovine reservoir for this organism.

Evaluation of a Polymerase Chain Reaction–Based System for Detection of Salmonella Enteritidis, Escherichia coli O157:H7, Listeria spp., and Listeria monocytogenes on Fresh Fruits and Vegetables

Article

Jul 2001

A polymerase chain reaction (PCR)-based detection system, BAX, was evaluated for its sensitivity in detecting Salmonella Enteritidis, Escherichia coli O157:H7, Listeria sp., and Listeria monocytogenes on fresh produce. Fifteen different types of produce (alfalfa sprouts, green peppers, parsley, white cabbage, radishes, onions, carrots, mushrooms, leaf lettuce, tomatoes, strawberries, cantaloupe, mango, apples, and oranges) were inoculated, in separate studies, with Salmonella Enteritidis, E. coli O157:H7, and L. monocytogenes down to the predicted level of 1 CFU per 25-g sample. Detection by BAX was compared to recovery of the inoculated bacteria by culture methods according to the Food and Drug Administration's (FDA) Bacteriological Analytical Manual (BAM). BAX was essentially as sensitive as the culture-based method in detecting Salmonella Enteritidis and L. monocytogenes and more sensitive than the culture-based method for the detection of E. coli O157:H7 on green pepper, carrot, radish, and sprout samples. Detection of the pathogenic bacteria in samples spiked with a predicted number of less than 10 CFU was possible for most produce samples, but both methods failed to detect L. monocytogenes on carrot samples and one of two mushroom and onion samples spiked with less than 100 CFU. Both BAX and the culture method were also unable to consistently recover low numbers of E. coli O157:H7 from alfalfa sprouts. The PCR method allowed detection of Salmonella Enteritidis, E. coli O157:H7, and L. monocytogenes at least 2 days earlier than the conventional culture methods.

Reduction of Listeria monocytogenes on Green Peppers (Capsicum annuum L.) by Gaseous and Aqueous Chlorine Dioxide and Water Washing and Its Growth at 7°C

Article

Dec 2001

Reduction of Listeria monocytogenes Scott A on uninjured and injured surfaces of green peppers after 0.3- and 3-mg/ liter gaseous and aqueous ClO2 treatment and water washing for 10 min at 20 degrees C was studied. Growth of the L. monocytogenes untreated or treated with 0.6 mg/liter ClO2 gas for 30 min at 20 degrees C on green peppers also was investigated. A membrane-surface-plating method was used for resuscitation and enumeration of L monocytogenes treated with ClO2. The bacterial viability on pepper surfaces was visualized using confocal laser scanning microscopy (CLSM). Live and dead cells of L. monocytogenes were labeled with a fluorescein isothiocyanate-labeled antibody and propidium iodide, respectively. More than 6 log CFU/5 g L. monocytogenes on uninjured surfaces and about 3.5 log CFU/5 g on injured surfaces were inactivated by both 3-mg/liter and 0.6-mg/liter ClO2 gas treatments. The 3-mg/liter aqueous ClO2 treatment achieved 3.7- and 0.4-log reductions on uninjured and injured surfaces, respectively; whereas, water washing alone showed 1.4- and 0.4-log reductions, respectively. ClO2 gas treatment was the most effective in reducing L. monocytogenes on both uninjured and injured green pepper surfaces, when compared with aqueous ClO2 treatment and water washing. The significant difference (P < 0.05) between log reductions on uninjured and injured surfaces and the results from CLSM analysis suggested that injured surfaces protected more bacteria from sanitation treatments than did uninjured surfaces. Not only could L. monocytogenes grow on green pepper surfaces at 7 degrees C, bacteria that survived the 0.6-mg/liter ClO2 gas treatment also could grow.

Differential efficacy of a chlorine dioxide-containing sanitizer against single species and binary biofilms of a dairy-associated Bacillus cereus and a Pseudomonas fluorescens isolate

Article

Feb 2002

Daily exposure to 100 p.p.m. chlorine dioxide of single species and binary biofilms of dairy-associated Bacillus cereus DL5 and Pseudomonas fluorescens M2, attached to stainless steel surfaces in a laboratory flow system, was studied. Surfaces were sampled daily before and after sanitizer treatment and cells and spores dislodged and enumerated by standard methods. Duplicate surfaces were prepared for confocal scanning laser microscopy (CSLM) and scanning electron microscopy. Higher counts of Ps. fluorescens M2 were obtained in single species biofilms, microcolonies stained green (viable) in CSLM images and were closely packed on attachment surfaces. By contrast, higher counts of B. cereus DL5 were obtained in binary biofilms, microcolonies stained green in CSLM images, but were more spread out. Lower spore counts were obtained for B. cereus DL5 in binary biofilms. The survival of Ps. fluorescens M2 cells after exposure to chlorine dioxide was apparently enhanced by the presence of B. cereus DL5 in binary biofilms. By contrast, B. cereus DL5 showed increased susceptibility to sanitizer treatment in the presence of Ps. fluorescens M2. Co-cultured bacteria in biofilms influence each other with respect to attachment capabilities and sanitizer resistance/susceptibility. Binary biofilms endemic in food-processing industries can survive sanitation regimes and may represent reservoirs of product contamination leading to subsequent spoilage and/or food safety risks.

The use of chlorine dioxide to control Alicyclobacillus acidoterrestris spores in aqueous suspension and on apples

Article

Apr 2004
INT J FOOD MICROBIOL

Alicyclobacillus acidoterrestris, a thermoacidophilic, spore-forming bacterium, has been identified as a spoilage organism in commercial, pasteurized fruit juices. This study was undertaken to evaluate chlorine dioxide for reducing numbers of A. acidoterrestris spores on laboratory media and on apples. A. acidoterrestris spores in aqueous suspension and on apple surfaces of four different cultivars were treated with several concentrations of chlorine dioxide. Spores in aqueous suspension treated with 40 ppm for 5 min were reduced by more than 4 log. Treatment with 80 ppm for 1 min and 120 ppm for 30 s resulted in about 1.8 log and 4.8 log reductions of spore viability, respectively, and treatment at 80 and 120 ppm for 5 min reduced spore viability to undetectable levels (<0.7 log CFU/ml). When applied to the surfaces of four different apple cultivars ('Red Delicious', 'Golden Delicious', 'Gala', and 'Fuji'), 40 ppm free chlorine dioxide reduced A. acidoterrestris spore numbers by 1.5, 3.2, 4.5, >4.8 log after 1-, 2-, 3-, and 4-min treatments, respectively. Spore numbers were reduced by >4.8 log with 120 ppm free chlorine dioxide after only 1-min treatment. However, there was no significant difference between apple cultivars (P>0.05) on spore reduction. These results show the great effectiveness of chlorine dioxide in controlling A. acidoterrestris spores both in aqueous suspension and on apple surfaces. There was no synergistic effect on spore reduction when chlorine dioxide treatment of aqueous suspension was followed by heat.

Efficacy of Chlorine Dioxide Gas as a Sanitizer of Lettuce Leaves

Article

Aug 2004

Aqueous solutions of sodium hypochlorite or hypochlorous acid are typically used to sanitize fresh fruits and vegetables. However, pathogenic organisms occasionally survive aqueous sanitization in sufficient numbers to cause disease outbreaks. Chlorine dioxide (ClO2) gas generated by a dry chemical sachet was tested against foodborne pathogens on lettuce leaves. Lettuce leaves were inoculated with cocktail of three strains each of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella Typhimurium and treated with CLO2 gas for 30 min, 1 h, and 3 h in a model gas cabinet at room temperature (22 +/- 2 degrees C). After treatment, surviving cells, including injured cells, were enumerated on appropriate selective agar or using the overlay agar method, respectively. Total ClO2, generated by the gas packs was 4.3, 6.7, and 8.7 mg after 30 min, 1 h, and 3 h of treatment, respectively. Inoculated lettuce leaves exposed to ClO2 gas for 30 min experienced a 3.4-log reduction in E. coli, a 4.3-log reduction in Salmonella Typhimurium, and a 5.0-log reduction in L. monocytogenes when compared with the control. After 1 h. the three pathogens were reduced in number of CFU by 4.4. 5.3, and 5.2 log, respectively. After 3 h, the reductions were 6.9, 5.4, and 5.4 log, respectively. A similar pattern emerged when injured cells were enumerated. The ClO2, gas sachet was effective at killing pathogens on lettuce without deteriorating visual quality. Therefore, this product can be used during storage and transport of lettuce to improve its microbial safety.

Efficacy of Chlorine Dioxide Gas Against Alicyclobacillus acidoterrestris Spores on Apple Surfaces

Article

Jun 2006
INT J FOOD MICROBIOL

Alicyclobacillus acidoterrestris is a thermophilic spore-forming bacterium that spoils acidic juices. In the orchard, apples may be contaminated with spores which can potentially grow in the resulting juice and cause spoilage. This study was undertaken to evaluate the efficacy of gaseous chlorine dioxide against A. acidoterrestris spores on apple surfaces. A. acidoterrestris spores were inoculated onto apple surfaces and were placed at room temperature, in a tightly sealed chamber containing a chlorine dioxide generating sachet, low, medium, or high release, for 30 min, 1, 2, and 3 h. After exposure, surviving spores were enumerated on K agar. Chlorine dioxide treated apples were stored at 4 degrees C for 7 days to assess the effect on visual quality. Inoculated, untreated apples served as the visual quality control. After exposure to high and medium release sachets for 1 h, spores were reduced to an undetectable level, a 5 log10 reduction; however, visual quality was compromised. After 1, 2, and 3 h of exposure to low release sachets, spore reductions were 2.7, 3.7, and 4.5 log10, respectively. And, after 7 days of storage, there were no significant visual quality differences between the apples exposed to low release sachet for all treatment times when compared to the control. Gaseous chlorine dioxide can effectively reduce viable A. acidoterrestris spores on apple surfaces. Due to the efficacy and easy of use, chlorine dioxide gas sachets may be useful to maintain apple quality during storage and shipping.

Don't Eat the Spinach — Controlling Foodborne Infectious Disease

Article

Dec 2006
NEW ENGL J MED

Dennis Maki

Between August 19 and September 5, symptomatic enteritis from Shiga toxin–producing E. coli O157:H7 infection was reported in 199 persons in 26 states in association with consumption of fresh spinach or spinach-containing products. Dr. Dennis Maki asks why outbreaks continue to occur in a country where food production and distribution are intensively regulated at every level.

H7 outbreak from fresh spinach

Nov 2006

Disease Control
E Prevention
O

Centers for Disease Control and Prevention. E. coli O157:H7 outbreak from fresh spinach. October 6, 2006 (Accessed October 10, 2007. Available at: /http://www.cdc.gov/foodborne/ecolispinach/S).

Effect of chemical sanitizer combined with modified atmosphere packaging on inhibiting Escherichia coli O157:H7 in commercial spinach

Abstract

No full-text available

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