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Bacteria of the cryptic lineage of genus Escherichia, or Escherichia cryptic clades (cryptic clades), are phenotypically indistinguishable from Escherichia coli (E. coli) using standard biochemical tests. Except for clade I (C-I), cryptic clades were hypothetically believed to be environmental but not enteric. If so, they would hinder the interpretation of current E. coli-based water quality (fecal pollution) monitoring in the United States because environmental bacteria do not indicate the presence of harmful fecal material. This study was performed to develop a rapid method for the detection of cryptic clades and to investigate their potential impact on water quality monitoring. By whole-genome comparison, one gene, named ecc (Escherichiacryptic clades), was identified to be unique to C-II through C-VIII. An end-point polymerase chain reaction (PCR) method, eccPCR, was developed by targeting the ecc. The results of in-silico and wet tests demonstrated 100 % sensitivity and specificity of the eccPCR to detect C-II through C-VIII. Based on the EPA Method 1603, 519 presumptive E. coli isolates were obtained from the fecal samples of 13 different host species and 192 isolates from surface water samples taken at four locations in a watershed of mid-Missouri. As indicated by the eccPCR amplification, the overall prevalence of C-II through C-VIII in the presumptive E. coli isolates was estimated to be about 0.6 % in the fecal samples and about 1.6 % in the water samples. Therefore, the potential impact of cryptic clades on water quality monitoring may be limited if EPA Method 1603 is used. Furthermore, clades C-II through C-VIII in stream water samples were found repeatedly only at a single sampling site, but neither at the upstream sites nor five kilometers downstream of the site. The data do not support nor reject the environmental hypothesis about cryptic clades. Further study is needed to determine the implication of the observation.

Recognizing the importance of food safety education toward students and stakeholders, the Food Safety and Microbiology program at Virginia State University (VSU) works continually to improve the safety and quality of our nation’s food supply through research, teaching and outreach. The program’s research is designed to increase knowledge of microbial ecology with regard to the routes of contamination from on-farm investigations to food distribution.The program also evaluates methods and approaches to better prevent, intervene and verify the presence of foodborne pathogens from farm to fork.

Buckwheat has been grown in Virginia since late 1700s; however, today the crop is almost non-existent in Virginia. Since buckwheat flowers profusely in a few weeks after planting, it has potential to support honeybees but there is a lack of information about quality of buckwheat honey produced in Virginia. Our objective was to characterize composition of honey produced by honeybees foraging on buckwheat (Buckwheat honey), compared to that produced by honeybees foraging on wild plants (Wild plant honey). Buckwheat honey differed in composition, antioxidant concentrations, and microbial activities from wild plant honey. Concentrations of fructose, glucose, and melezitos in buckwheat honey were quantitatively lower than that in wild plant honey whereas concentrations of sucrose and maltose exhibited an opposite trend—concentration of maltose being statistical significant. Fructose was the dominant sugar (42 and 52 percent in buckwheat honey and wild plant honey, respectively). Buckwheat honey had significant higher concentrations of K and Cu in comparison to wild plant honey (0.17 and 0.04 percent, and 5.0 and 3.33 ppm, respectively). Concentrations of Trolox and TPC were significantly higher in buckwheat honey than wild plant honey (1.01 and 0.32, and 0.39 and 0.17, respectively). Both types of honeys exhibited anti-microbial activity against gram-positive and gram-negative bacteria. The buckwheat honey was darker in color than the honey from wild plants. We concluded that production of buckwheat as a grain or cover crop can also support honeybees and buckwheat honey might be superior to wild plant honey.

Improper food processing is one of the major causes of foodborne illness. Accurate prediction of the thermal destruction rate of foodborne pathogens is therefore vital to ensure proper processing and food safety. When bacteria are subjected to pH and thermal stresses during growth, sublethal stresses can occur that may lead to differences in their subsequent tolerance to thermal treatment. As a preliminary study to test this concept, the current study evaluated the effect of prior pH and thermal stresses on thermal tolerance of Salmonella and Staphylococcus using a tryptic soy broth supplemented with yeast extract. Bacteria incubated at three pH values (6.0, 7.4, and 9.0) and four temperatures (15, 25, 35, and 45°C) for 24 hr were subjected to thermal treatments at 55, 60, and 65°C. At the end of each treatment time, bacterial suspensions were surface‐plated on standard method agar for quantification of bacterial survival and further calculation of the thermal death decimal reduction time (D‐value) and thermal destruction temperature (z‐value). The effect of pH stress alone during the incubation on the thermal tolerance of both bacteria was generally insignificant. An increasing pattern of D‐value was observed with the increment of thermal stress (incubation temperature). The bacteria incubated at 35°C required the highest z‐value to reduce the 90% in D‐values. Staphylococcus mostly displayed higher tolerance to thermal treatment than Salmonella. Although further research is needed to validate the current findings on food matrices, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation procedures applied during later stage of food processing and storage.

Background Little is known on significance, diversity and characteristics of gut E. coli in goats despite their importance as food animals globally. We characterized the temporal dynamics in diversity of E. coli in fecal samples from a cohort of goat kids and adult meat goats on pasture over a one-year period. Isolates were characterized based on phylogenetic grouping, virulence genes; shiga toxins 1 and 2 (Stx1&Stx2) (STEC), intimin (eaeA), hemolysin (hly) and select important sero-groups (026, 045, 0103, 0126 and 0146) using molecular methods. Results A total of 516 E. coli isolates were screened. Prevalence of virulence genes and STEC was 65 and 56% respectively. Prevalence of virulence genes and STEC was significantly higher in goat kids less than six months (76% /66%) than adults (48% /28%). Isolates with virulence profiles of two or more genes were also higher in young goat kids (50%) than adults (20%). Entero-pathogenic E. coli (EPEC-eaeA gene only) were mostly from pre-weaned goat kids while hly gene only isolates were significantly higher in adults. The stx1, stx2 and hly genes peaked around weaning (60, 63 and 52%) respectively. Goats kids were mostly hosts to group D (59%) while adults older than one year had B1 (75%) isolates. Group D isolates were most abundant at weaning (64%) and diarrhea samples (74%). Group B2 isolates overall (6%) were mostly detected around weaning (63%) while A isolates were 4% overall. Twenty-four isolates belonged to sero-groups 026, 0103 and 0146 with 70% of the isolates detected around weaning. Nineteen of these isolates were STEC with most harboring the stx1/stx2/hly/eae (25%) profile. Most belonged to O26 sero-group (75%) and phylogroup D (75%). Conclusion To our knowledge this is the first study to highlight longitudinal age related differences in E. coli phylogenetic diversity, abundance of virulence genes and select important sero-groups in goats. Differences detected suggest a possible role of age and weaning stress in influencing E. coli diversity in the gut of goats. The findings are relevant to both animal and public health to advise on further studies on caprine E. coli isolates as animal and human pathogens.

Accurate prediction of the thermal destruction rate of foodborne pathogens is important for food processors to ensure proper food safety. When bacteria are subjected to thermal stress during storage, sublethal stresses and/or thermal acclimation may lead to differences in their subsequent tolerance to thermal treatment. The aim of the current study was to evaluate the thermal tolerance of Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Staphylococcus aureus that are incubated during overnight growth in tryptic soy broth at four temperatures (15, 25, 35, and 45°C). Following incubation, the bacteria were subjected to thermal treatments at 55, 60, and 65°C. At the end of each treatment time, bacterial survival was quantified and further calculated for the thermal death decimal reduction time (D‐value) and thermal destruction temperature (z‐value) using a linear model for thermal treatment time (min) vs. microbial population (Log CFU/ml) and thermal treatment temperature (°C) vs. D‐value, respectively, for each bacterium. Among the four bacterial species, E. coli generally had longer D‐values and lower z‐values than did other bacteria. Increasing patterns of D‐ and z‐values in Listeria were obtained with the increment of incubation temperatures from 15 to 45°C. The z‐values of Staphylococcus (6.19°C), Salmonella (6.73°C), Listeria (7.10°C), and Listeria (7.26°C) were the highest at 15, 25, 35, and 45°C, respectively. Although further research is needed to validate the findings on food matrix, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation hurdles applied during later stages of food processing and storage., When bacteria are subjected to thermal shock during storage, sublethal stresses and/or thermal acclimation may lead to differences in their subsequent tolerance to thermal treatment. We found that increasing pattern of bacterial thermal tolerance was observed with the increment of thermal stress. Although further research is needed to validate the current findings on food matrices, findings in this study clearly affirm that adaptation of bacteria to certain stresses may reduce the effectiveness of preservation procedures applied during later stage of food processing and storage.

Tapioca starch active nanocomposite films were prepared by incorporating cellulose nanocrystal and two grape pomace extracts (Cabernet Franc (red variety) and Viognier (white variety) using a solvent casting method. Their physical properties and antibacterial activities were characterized. Incorporating cellulose nanocrystal significantly (P

There is a scarcity of information on antibiotic resistance in goats. To understand shedding of resistant Escherichia coli in pastured goats, we collected fecal samples from a mixed age cohort over a one-year period. No antibiotic had been used on the study animals one year prior to and during the study period. Resistant isolates were detected in all age groups and prevalence in goat kids was significantly higher than adults; 43–48% vs. 8–25% respectively. The proportion of resistant isolates was higher when animals were congregated near handling facility than on pasture. Most isolates were resistant to tetracycline (51%) and streptomycin (30%), but also to antibiotics that had never been used on the farm; ampicillin (19%). TetB, bla-TEM, (aadA and strpA/strpB) genes were detected in 70%, 43%, (44% and 24%) of tetracycline, ampicillin, and streptomycin resistant isolates respectively. Resistant isolates also harbored virulent genes and some belonged to D and B2 phylogenetic groups. Thus, pastured goats, despite minimal exposure to antibiotics, are reservoirs of resistant E. coli that may contaminate the environment and food chain and spread resistant genes to pathogenic bacteria and some that are potential animal and human pathogens. Environmental sources may play a role in acquisition of resistant bacteria in pastured goats.

This study was conducted to evaluate the microbial quality of lamb and goat meat sold through local (Virginia) and Internet (U. S.) retail markets. A total of 134 frozen meat products consisting of locally purchased lamb ground (LLG) and lamb chops and Internet-procured lamb ground, goat ground, lamb chops (ILC), goat chops (IGC), lamb stew, and goat stew were tested. Significantly higher levels of aerobic mesophiles, psychrotrophs, and coliforms were found in the meat locally acquired than in the meat procured from the Internet. Similar average prevalence (27%) of Escherichia coli was observed regardless of market source. Ground meat had significantly high levels and prevalence of mesophiles, psychrotrophs, coliforms, and Listeria spp. One sample of LLG contained Campylobacter, and one sample of IGC contained Salmonella. Listeria spp. were present in 23 to 40% and 17 to 80% of samples from local and Internet markets, respectively. Pulsed-field gel electrophoresis (PFGE) of isolated E. coli strains revealed brand specificity and genomic diversity. No isolate from different brands and market sources had matching PFGE profiles. The average price of Internet meat ($23.4/kg) was about 1.2 times higher than the price of local meat, except for ILC, whose price was 2.7 times higher. This study revealed differences in microbial quality of lamb and goat meat based on market source; thus, meat products should be handled carefully regardless of market source because of the presence of high microbial levels and the high prevalence of pathogens.

Small fruits are a multi-billion dollar industry in the US, and are economically important in many other countries. However, they are perishable and susceptible to physiological disorders and biological damage. Food safety and fruit quality are the major concerns of the food chain from farm to consumer, especially with increasing regulations in recent years. At present, the industry depends on pesticides and fungicides to control food spoilage organisms. However, due to consumer concerns and increasing demand for safer produce, efforts are being made to identify eco-friendly compounds that can extend the shelf life of small fruits. Most volatiles and essential oils produced by plants are safe for humans and the environment, and lots of research has been conducted to test the in vitro efficacy of single-compound volatiles or multi-compound essential oils on various microorganisms. However, there are not many reports on their in vivo (in storage) and In situ (in the field) applications. In this review, we discuss the efficacy, minimum inhibitory concentrations, and mechanisms of action of volatiles and essential oils that control microorganisms (bacteria and fungi) on small fruits such as strawberries, raspberries, blueberries, blackberries, and grapes under the three conditions.

Grape pomace is a potential source of natural antioxidant and antimicrobial agents. Phenolic compounds, antioxidant, and antibacterial properties of pomace extracts from four Virginia‐grown grape varieties were investigated. White grape pomaces had higher (P

A total of 689 co-grazing small ruminants along with 446 wild-living birds were tested during two springs and autumns (2007–2009) under two management systems at two Mid-Atlantic locations (~187 km in aerial distance) of the U.S. Fecal shedding of Campylobacter jejuni and Salmonella spp. were, respectively, detected in 9.3% and 3.5% of small ruminants and in 7.4% and 0.2% of wild-living birds. Sheep had a significantly higher prevalence of C. jejuni and Salmonella than goats, but there were no differences due to season, location, or management. Pulsed field gel electrophoresis (PFGE) of isolated strains revealed geographic specificity and genomic diversity of both pathogens from small ruminants. However, C. jejuni strains with indistinguishable PFGE profiles were isolated from one Rock Dove and two European Starlings caught at separate locations. Matching C. jejuni or Salmonella strain profiles were not found between small ruminants and wild-living birds. This study found that sheep pose a greater risk than goats in C. jejuni and Salmonella contamination at co-grazing small ruminant farms. Wild-living birds also are potential carriers of C. jejuni and Salmonella although no evidence of cross-contamination with small ruminants was established.

Salmonella enterica serovar Newport pattern JJPX01.0061 has been identified as causing several multistate outbreaks in the last 10 years, primarily due to contamination of tomatoes grown in Virginia. The goal of this study was to evaluate gulls as a potential vehicle of S . Newport pattern 61 contamination for tomatoes grown on the Eastern Shore of Virginia. Gull fecal samples were collected at four sites in eastern Virginia for 3 months (May to July) in 2012, resulting in 360 samples, among which Salmonella was isolated from 62 samples. Twenty-two serotypes and 26 pulsed-field gel electrophoresis DNA fingerprint patterns, including S . Newport pattern 61, were identified. All of the patterns that were isolated multiple times, with the exception of S . Newport patterns JJPX01.0030 and JJPX01.0061, were clustered in time and geographical location. These results strongly suggest that both patterns of S . Newport are endemic to sites on the Eastern Shore where gulls were sampled. This study provides additional information regarding the epidemiology of S . Newport pattern 61 in Virginia and how tomatoes sold interstate may become contaminated in the field.

The objectives of this study were to prepare starch nanocomposite films incorporating grape pomace extract (GPE) and cellulose nanocrystal (CNC) using a solvent-casting method, and to characterize the mechanical properties, color, water vapor transmission rate (WVTR), crystalline structure, morphology, thermal stability, phenolic compound release profile and antibacterial activity of the films. Incorporating CNC and GPE significantly (P

Increased interest in blueberries due to their nutritional and health benefits has led to an increase in consumption. However, blueberries are consumed mostly raw or minimally processed and are susceptible to microbial contamination like other type of fresh produce. This study was, therefore, undertaken to evaluate the efficacy of electrostatic spray of electrolyzed oxidizing (EO) water, UV light, ozone, and a combination of ozone and UV light in killing Escherichia coli O157:H7 on blueberries. A 5-strain mixture of E. coli O157:H7 were inoculated on the calyx and skin of blueberries and then subjected to the treatments. Electrostatic EO water spray reduced initial populations of E. coli O157:H7 by only 0.13 to 0.24 log CFU/g and 0.88 to 1.10 log CFU/g on calyx and skin of blueberries, respectively. Ozone treatment with 4000 mg/L reduced E. coli O157:H7 by only 0.66 and 0.72 log CFU/g on calyx and skin of blueberries, respectively. UV light at 20 mW/cm2 for 10 min was the most promising single technology and achieved 2.14 and greater than 4.05 log reductions of E. coli O157:H7 on the calyx and skin of blueberries, respectively. The combination treatment of 1 min ozone and followed by a 2 min UV achieved more than 1 and 2 log additional reductions on blueberry calyx than UV or ozone alone, respectively. Practical Application: Outbreaks of foodborne illnesses have been associated with consumption of fresh produce. Many methods for removing pathogens as well as minimizing their effect on quality of treated produce have been investigated. UV technology and its combination with ozone used in this study to inactive E. coli O157:H7 on blueberries was found effective. Results from this study may help producers and processors in developing hurdle technologies for the delivery of safer blueberries to consumers.

Strawberries and broccoli were treated for 5 min with 4C tap water, chlorinated water or electrolyzed oxidizing water (55 and 100 mg/L chlorine, respectively) with or without ultrasonication. Several quality parameters (weight loss, shear force, color, pH, titratable acidity, soluble solids and decay) were evaluated to estimate the effect of treatments on consumer acceptability during storage at 4C. Strawberries were examined on the initial day of experiments and at 3, 6, 9 and 13 days of storage, and broccoli on the initial day as well as at 5, 10, 14 and 21 days of storage. On each day of analysis, weight loss, decay and color (L*a*b* values, chroma, hue angle, total color difference) were evaluated. On the last day of storage, texture was measured as force (Newton) needed to shear each sample. For strawberry, samples were also tested for pH, titratable acidity (%) and soluble solids content. No significant differences in quality were detected among strawberries and broccoli subjected to different treatments, and between treated samples and control at any of the sampling times. However, quality of strawberries treated with chlorinated water was significantly affected with respect to weight loss and decay, whereas only decay was significantly affected when broccoli was treated with chlorinated water. PRACTICAL APPLICATIONS Electrolyzed oxidizing (EO) water has been demonstrated to inactivate Escherichia coli O157:H7 on strawberries and broccoli during a washing treatment. This study found no significant differences in quality among strawberries and broccoli subjected to EO water treatments when compared with the tap water washing treatment or the control (no washing).

Inoculated strawberries were treated with deionized water (control), electrolyzed oxidizing (EO) water (23 and 55 mg/L of residual chlorine), and chlorinated water (55 mg/L of residual chlorine), either with or without ultrasonication. Inoculated broccoli was treated with EO water containing 55 and 100 mg/L of residual chlorine and chlorinated water with 100 mg/L of residual chlorine. Treatments were conducted for 1 and 5 min at temperatures of 4 and 24C, respectively. Dipping strawberries and broccoli into EO water or chlorinated water significantly (P

Electrostatic forces have been applied during the spraying of a target to enhance energy efficiency, reduce resource input and environmental pollutant output, and improve overall product quality and economic competitiveness. This study was therefore undertaken to develop a prediction response surface methodology (RSM) model of an electrostatic spray system to maximize solution attachment on the target. A ball with a surface area of 77.3 cm2 was used as a model to simulate a spherical food sample. Results indicated that the cross-products of height decrement and distance from the target to the sprayer nozzle were the most significant contributing factors for solution attachment to the front and back sides of the target, respectively. Multiple regression yielded models to predict solution attachment as functions of the contributing factors studied (air pressure from 138 to 276 kPa, distance from 80 to 120 cm, and height decrement from 10 to 20 cm) with coefficients of determination (R2) of 0.69 and 0.75 for the front and back sides of the target, respectively. Within the range of parameters tested, the response predictive model suggested that 7 s of electrostatic spraying with parameter values of 276 kPa air pressure, 100 cm distance, and 10 cm height decrement using a 1.50 mm disk orifice would achieve the most efficient solution attachment to the target. Verification studies on tomatoes and apples supported the findings that electrostatic charge enhanced spray efficiency and uniformity. This study may hence provide guidelines for the development of effective spray applications, such as sanitizing or watering target food materials.

The effectiveness of electrolyzed (EO) water at killing Enterobacter aerogenes and Staphylococcus aureus in pure culture was evaluated. One milliliter (approximately 10(9) CFU/ml) of each bacterium was subjected to 9 ml of EO water or control water (EO water containing 10% neutralizing buffer) at room temperature for 30 s. Inactivation (reduction of9 log10 CFU/ ml) of both pathogens occurred within 30 s after exposure to EO water containing approximately 25 or 50 mg of residual chlorine per liter. The effectiveness of EO water in reducing E. aerogenes and S. aureus on different surfaces (glass, stainless steel, glazed ceramic tile, unglazed ceramic tile, and vitreous china) was also evaluated. After immersion of the tested surfaces in EO water for 5 min without agitation, populations of E. aerogenes and S. aureus were reduced by 2.2 to 2.4 log10 CFU/ cm2 and by 1.7 to 1.9 log10 CFU/cm2, respectively, whereas washing with control water resulted in a reduction of only 0.1 to 0.3 log10 CFU/cm2. The washing of tested surfaces in EO water with agitation (50 rpm) reduced populations of viable cells on the tested surfaces to1 CFU/cm2. For the control water treatment with agitation, the surviving numbers of both strains on the tested surfaces were approximately 3 log10 CFU/cm2. No viable cells of either strain were observed in the EO water after treatment, regardless of agitation. However, large populations of both pathogens were recovered from control wash solution after treatment.

Nonlinear flexural deflection behavior of foam core sandwich beams hasbeen experimentally investigated. The experimental data were compared with the predicted results obtained from a proposed analytical method and the finite element analysis. Sandwich beams with thermoplastic foam core and carbon/epoxy fabric faces were manufactured using the vacuum bagging process. To investigate the effect of the face thickness on the nonlinear flexural deflection, three types of specimens with different face thickness were prepared and tested using the four-point bending test method. Basic engineering data and nonlinear mechanical properties of the face sheet and the foam core were obtained from the tensile and shear tests. An analytical model wasproposed to predict the global nonlinear flexural deformation of the foam core sandwich beams. In the model, measured material nonlinear behavior of the foam core wasimplemented. The predicted global nonlinear deflection of the foam core sandwich beam using the proposed analytical model and the finite element analysis agreed well with the experimental data up to the local indentation failure point within some scattered range.

The efficacy of electrolyzed oxidizing (EO) and acidified chlorinated water (45 ppm residual chlorine) was evaluated in killing Escherichin coli O157:H7 and Listeria monorytogenes on lettuce. After surface fooculation, each leaf was immersed in 1.5 L of EO or acidified chlotinated water for 1 or 3 min at 22 °C. Compared to a water wash only, the EO water washes significantly decreased mean populations of E. coli O157:H7 and L. monocytogenes by 2.41 and 2.65 log 1 0 CFU per lettuce leaf for 3 min treatments, respectively (p = 0.05), However, the difference between the bactericidal activity of EO and acidified chlorinated waters was not significant (p ≥ 0.05). Change in the quality of lettuce subjected to the different wash treatments was not significant at the end of 2 wk of storage.

This study investigates the resistance of Listeria monocytogenes biofilms on stainless steel surfaces to electrolyzed oxidizing (EO) water. A direct agar overlay method was used to estimate the attached bacteria on stainless steel coupons after an EO water treatment. A scraping method was also used to quantify the adherent cell populations after the EO water treatment. The stainless steel surface allowed 10 to 15% of the surface area to be covered by Listeria biofilm when the inoculated stainless steel coupon was incubated in 10% tryptic soy broth (TSB) at 23C for 48 h. When the stainless steel coupons containing adherent cells were treated with EO water (56 mg/L of residual chlorine) for 10, 30, 60, 180, and 300 s, adherent cell populations (10.3 log 10 CFU/coupon) were reduced with increasing treatment time. Although the direct agar overlay methods do not quantify survival of single bacteria, only one to five cell clumps per coupon survived after 300 s of the EO water treatment. Using the scraping method, the adherent cell population on the stainless steel coupons was reduced by about 9 log cycles after 300 s of EO water treatment.

This study was undertaken to evaluate the efficacy of electrolyzed oxidizing (EO) and chemically modified water with properties similar to the EO water for inactivation of different types of foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes and Bacillus cereus). A five-strain cocktail of each microorganism was exposed to deionized water (control), EO water and chemically modified water. To evaluate the effect of individual properties (pH, oxidation-reduction potential (ORP) and residual chlorine) of treatment solutions on microbial inactivation, iron was added to reduce ORP readings and neutralizing buffer was added to neutralize chlorine. Inactivation of E. coli O157:H7 occurred within 30 s after application of JAW EO water with 10 mg/l residual chlorine and chemically modified solutions containing 13 mg/l residual chlorine. Inactivation of Gram-positive and -negative microorganisms occurred within 10 s after application of ROX EO water with 56 mg/l residual chlorine and chemically modified solutions containing 60 mg/l residual chlorine. B. cereus was more resistant to the treatments than E. coli O157:H7 and L. monocytogenes and only 3 log10 reductions were achieved after 10 s of ROX EO water treatment. B. cereus spores were the most resistant pathogen. However, more than 3 log10 reductions were achieved with 120-s EO water treatment.

The potential of Salmonella population to rebound on non-washed and washed roma tomatoes and jalapeño peppers in humid storage at 4°C, 10°C, 15°C, 21°C, or 35°C for ≤12 days was investigated. The initial inoculation levels of Salmonella on peppers and tomatoes were 5.6 and 5.2 log CFU/cm(2), respectively. Air-drying of fruit surfaces resulted in contamination levels of 3.9 and 3.7 log CFU/cm(2) on inoculated peppers and tomatoes, respectively. At 21°C and 35°C, the levels of air-dried Salmonella inoculums on produce surfaces increased ≥2 log cycles, with the most rapid growth in the first 3 days. Mechanical washing on rollers (rinsing; R-treatment) or revolving brushes (rinsing and brushing; RB-treatment) with water decreased Salmonella counts by ≥2.5 log CFU/cm(2) on both peppers and tomatoes. After R- or RB-treatment, peppers stored at 21°C and 35°C permitted residual Salmonella (≤1.4 log CFU/cm(2)) to grow to 2.6-3.9 log CFU/cm(2). During storage, residual Salmonella (≤1.0 log CFU/cm(2)) on washed tomatoes increased to 3.1 log CFU/cm(2) at 35°C following R-treatment and 3.8 log CFU/cm(2) at 21°C following RB-treatment. Cold storage at 4°C and 10°C effectively prevented the proliferation of Salmonella on both washed and non-washed produce. The current study on jalapeño peppers and roma tomatoes demonstrated that Salmonella population can rebound on produce in humid storage before or after washing. The finding highlights the benefit of uninterrupted cold storage for safer produce operations.

A convenient bread making method involving prolonged fermentation of no-knead (nonkneaded) dough has become popular in recent years. In the present study, the microbial safety of no-knead dough made with a 375:325:5:1 weight ratio of flour, water, salt, and bread yeast was investigated. Three brands of dehydrated yeast were used for this study. The growth of inoculated Salmonella enterica and Staphylococcus aureus in no-knead dough during fermentation was significant (P

Probiotic supplements have received worldwide attention due to their health benefits. One of the most commonly used probiotics is Lactobacillus reuteri, which has known to help prevent and treat both viral and bacterial diarrhea enhancing the body’s resistance to gastrointestinal disease. In order to survive and colonize in the gastrointestinal tract, L. reuteri should express high tolerance to bile salt. This study was therefore undertaken to determine the effect of bile salt on the growth and s-galactosidase activities of L. reuteri. The effect of Tween 80 on the promotion of L. reuteri tolerance against bile salt was also determined. Five strains (CF2F, DSM20016, MM2-3, and MM7) of L. reuteri used for this study were subjected to MRS broth supplemented with various concentrations (0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 2.0, and 4.0%) of bile salt. Bacterial growth was then monitored using a spectrophotometer (610 nm) for 10 h at 37°C. Results showed that 0.3% bile salt significantly (P

Apple skins generally are not used in food products and often are discarded as waste. Apple skin contains several useful nutrients particularly sugars and more complex carbohydrates. This study was undertaken to determine the feasibility of apple skin waste as a media source for the production of lactic acid (LA) using Lactobacillus reuteri. One to nine ratios (10%) of apple skin to water was boiled for 5 min and its filtrate was then added with each of following supplements, respectively; ammonium phosphate, manganese sulfate, peptone, yeast extract, and potassium phosphate monobasic and dibasic. The efficacy of apple skin filtrates with and without supplements was determined by measuring pH, glucose and lactic acid after 2, 4 and 8 h fermentation at 37°C. Moreover, apple skin filtrate was also compared with MRS broth and G-M17 broth for the efficacy of glucose utilization and LA production. At the end of 8 h incubation, pH of apple skin filtrates with peptone and yeast extract reduced from 7 to ∼4. The LA concentrations produced from the filtrates with either peptone or yeast extract supplement were the greatest ranging from 0.9 g/L to 1.9 g/L. The efficacy of LA production using apple skin filtrate was about the same as G-M17 broth. Higher amount of LA was yielded with media inoculated with immobilized (encapsulated) cells than free cell. Results also indicated that immobilized L. reuteri MM2-3 produced 40% higher amount of LA than free cell. The results obtained from this study indicate that apple skins as a carbohydrate source and immobilization of lactic acid bacteria (LAB) could be a promising method for the production of LA. Further study is necessary to identify ways to increase glucose availability and promote LAB growth and LA production.

Lactic acid (LA) is the most widely used multifunctional organic acid and approximately 50% of it is produced by biotechnological process. Immobilizing microbial cells not only improves cell retention but also protects cells from harsh environmental conditions during LA production. The objectives of this research were therefore to develop a simple method to encapsulate (immobilize) Lactobacillus reuteri for the continuous production of LA and to evaluate LA production in three different types of media using free and immobilized L. reuteri.Five strains of L. reuteri grown in lactobacillusMRS broth at 37°C for 24 h were washed in peptone water and suspended in 2% sodium alginate solution. Encapsulation of cells was performed by dripping the mixture of sodium alginate and culture into ice-cold (2°C) 0.4 M calcium chloride solution using a separator funnel. The beads were then subjected to each of 500 ml MRS, modified MRS and whey-based broth and then incubated at 37°C for 12 h. Samples were withdrawn at 2-hour intervals during incubation period and analyzed for LA as represented in pH. Results show that the developed method is a rapid and simple microbial encapsulation procedure for the continuous production of LA. The efficacy of LA production as measured in pH was not significantly different in all tested media. At the end of fermentation process, pH of whey medium containing conventional (free) and encapsulated cells reached to 4.20 and 3.85, respectively. This indicates that higher amount of acid is yielded with encapsulated cells than free cells. In addition, immobilized cell strain MM2-3 produced the highest pH (3.5) while free cell strain SD2112 produced the lowest pH (4.05). Hence, results from this study suggest that we were able to develop a simple and rapid method for the encapsulation of L. reuteri.

The ability of electrolyzed (EO) water to inactivate Listeria monocytogenes in suspension and biofilms on stainless steel in the presence of organic matter (sterile filtered chicken serum) was investigated. A five-strain mixture of L. monocytogenes was treated with deionized, alkaline EO, and acidic EO water containing chicken serum (0, 5, and 10 ml/liter) for 1 and 5 min. Coupons containing L. monocytogenes biofilms were also overlaid with chicken serum (0, 2.5, 5.0, and 7.5 ml/liter) and then treated with deionized water, alkaline EO water, acidic EO water, alkaline EO water followed by acidic EO water, and a sodium hypochlorite solution for 30 and 60 s. Chicken serum decreased the oxidation-reduction potential and chlorine concentration of acidic EO water but did not significantly affect its pH. In the absence of serum, acidic EO water containing chlorine at a concentration of 44 mg/liter produced a6-log reduction in L. monocytogenes in suspension, but its bactericidal activity decreased with increasing serum concentration. Acidic EO water and acidified sodium hypochlorite solution inactivated L. monocytogenes biofilms to similar levels, and their bactericidal effect decreased with increasing serum concentration and increased with increasing time of exposure. The sequential 30-s treatment of alkaline EO water followed by acidic EO water produced 4- to 5-log reductions in L. monocytogenes biofilms, even in the presence of organic matter.

Studies have demonstrated that electrolyzed oxidizing (EO) water is effective in reducing foodborne pathogens on fresh produce. This study was undertaken to determine the efficacy of EO water and two different forms of chlorinated water (chlorine water from Cl2 and Ca(OCl)2 as sources of chlorine) in inactivating Salmonella on alfalfa seeds and sprouts. Tengram sets of alfalfa seeds inoculated with a five-strain cocktail of Salmonella (6.3 x 10(4) CFU/g) were subjected to 90 ml of deionized water (control), EO water (84 mg/liter of active chlorine), chlorine water (84 mg/liter of active chlorine), and Ca(OCl)2 solutions at 90 and 20,000 mg/liter of active chlorine for 10 min at 24 +/- 2 degrees C. The application of EO water, chlorinated water, and 90 mg/liter of Ca(OCl)2 to alfalfa seeds for 10 min reduced initial populations of Salmonella by at least 1.5 log10 CFU/g. For seed sprouting, alfalfa seeds were soaked in the different treatment solutions described above for 3 h. Ca(OCl)2 (20,000 mg/liter of active chlorine) was the most effective treatment in reducing the populations of Salmonella and non-Salmonella microflora (4.6 and 7.0 log10 CFU/g, respectively). However, the use of high concentrations of chlorine generates worker safety concerns. Also, the Ca(OCl)2 treatment significantly reduced seed germination rates (70% versus 90 to 96%). For alfalfa sprouts, higher bacterial populations were recovered from treated sprouts containing seed coats than from sprouts with seed coats removed. The effectiveness of EO water improved when soaking treatments were applied to sprouts in conjunction with sonication and seed coat removal. The combined treatment achieved 2.3- and 1.5-log10 CFU/g greater reductions than EO water alone in populations of Salmonella and non-Salmonella microflora, respectively. This combination treatment resulted in a 3.3-log10 CFU/g greater reduction in Salmonella populations than the control (deionized water) treatment.

Three-factor three-by-three-by-two-level factorial designs were adopted for studying the effects of air pressure, sprayer orifice size and electrostatic charge of a spray gun on pH, oxidation-reduction potential (ORP), electric conductivity and residual chlorine of electrolyzed oxidizing (EO) waters with either low ( 72 ppm) of chlorine. Results indicated that small orifice reduced more ORP and chlorine than large orifices. Electrostatic charge, in general, did not have significant effect. High air pressure spray retained more chlorine and yielded higher OPR than at low air pressure. High-chlorine EO water achieved at least 3 to 4 log10 CFU/mL reduction on Listeria monocytogenes populations when sprayed with the spray gun while sprayed with a commercial backpack sprayer or a poly-tank sprayer eliminated Listeria completely. These results demonstrated that although spraying reduced 20 to 97% of the chlorine in EO water, application of EO water through spraying still has good potential for reducing bacteria in food-processing operations.

To identify the primary component responsible in electrolyzed oxidizing (EO) water for inactivation, this study determined the concentrations of hypochlorous acid (HOCl) and hypochlorite ions (OCl-) and related those concentrations to the microbicidal activity of the water. The ultraviolet absorption spectra were used to determine the concentrations of HOCl and OCl- in EO water and the chemical equilibrium of these species with change in pH and amperage. EO water generated at higher amperage contained a higher chlorine concentration. The maximum concentration of HOCl was observed around pH 4 where the maximum log reduction (2.3 log10 CFU/ml) of Bacillus cereus F4431/73 vegetative cells also occurred. The high correlation (r = 0.95) between HOCl concentrations and bactericidal effectiveness of EO water supports HOCl's role as the primary inactivation agent. Caution should be taken with standard titrimetric methods for measurement of chlorine as they cannot differentiate the levels of HOCl present in EO water of varying pHs.

This study investigates the properties of electrolyzed oxidizing (EO) water for the inactivation of pathogen and to evaluate the chemically modified solutions possessing properties similar to EO water in killing Escherichia coli O157:H7. A five-strain cocktail (10(10) CFU/ml) of E. coli O157:H7 was subjected to deionized water (control), EO water with 10 mg/liter residual chlorine (J.A.W-EO water), EO water with 56 mg/liter residual chlorine (ROX-EO water), and chemically modified solutions. Inactivation (8.88 log10 CFU/ml reduction) of E. coli O157:H7 occurred within 30 s after application of EO water and chemically modified solutions containing chlorine and 1% bromine. Iron was added to EO or chemically modified solutions to reduce oxidation-reduction potential (ORP) readings and neutralizing buffer was added to neutralize chlorine. J.A.W-EO water with 100 mg/liter iron, acetic acid solution, and chemically modified solutions containing neutralizing buffer or 100 mg/liter iron were ineffective in reducing the bacteria population. ROX-EO water with 100 mg/liter iron was the only solution still effective in inactivation of E. coli O157:H7 and having high ORP readings regardless of residual chlorine. These results suggest that it is possible to simulate EO water by chemically modifying deionized water and ORP of the solution may be the primary factor affecting microbial inactivation.