Nanocoating and its application as antimicrobials in the food industry: A review.

Nanocoatings are ultra-thin layers on the nanoscale (<100 nm) that are deposited on the substrate to improve their properties and functionality. These nanocoatings provide significant advantages compared to traditional coating, including stain resistance, antimicrobial and antioxidant activities, odor control and delivery of active agents, and liquid repellence properties. In the food industry, nanocoating is widely used in the food packaging sector. In this regard, nanocoating offers antimicrobials and antioxidant properties to active food packaging by incorporating active bioactive compounds into materials used in already existing packaging. The application of nanocoating is applied to these kinds of food packaging with nano coating to improve shelf life, safety, and quality of food packaging. In smart/intelligent packaging, the active packaging coating is promising food packaging, which is designed by releasing preservatives and nanocoating as an antimicrobial, antifungal, antioxidant, barrier coating, and self-cleaning food contact surfaces. In addition, nanocoating can be used for food contact surfaces, kitchen utensils, and food processing equipment to create antimicrobial, antireflective, and dirt-repellent properties. These are critical properties for food processing, especially for meat and dairy processing facilities, which can reduce biofilm formation and prevent cross-contamination. Recently, appreciable growth in the development of the application of nanocoating as edible films for coating food products has emerged to improve food safety issues. In this regard, much scientific research in the area of nanocoating fruits and vegetables, and other food products was performed to address food safety issues. Hence, this promising technology can be a great addition to the agricultural and food industries. Thus, this review addresses the most relevant information about this technology and the applications of nanocoating in the food industry.

Comparative microbial analyses of hydroponic versus in-soil grown Romaine lettuce obtained at retail.

The overarching goal of this study was to assess the microbiological profile of hydroponically grown Romaine lettuce and in-soil Romaine lettuce (organic and conventional). Thirty-six samples of hydroponic lettuce, seventy-two samples organic lettuce (thirty-six bagged lettuce and thirty-six non-bagged lettuce), and thirty-six conventionally grown lettuce was purchased from retail stores. A portion of each sample was analyzed for aerobic bacteria (APC), coliforms and E. coli, and yeasts and molds (YM). Another portion of each sample was enriched for Salmonella, E. coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus, and confirmed with RT-PCR. No statistical differences were found in the microbial profile (P > 0.05) between the different farming practices. The APC, coliforms, E. coli, and YM counts were similar across bagged samples. The results demonstrated that APC and E. coli were significantly higher (P<0.05) in organic non-bagged samples compared to other practices. Salmonella and L. monocytogenes were detected in some organically and conventionally grown lettuce samples but were only detected in 3 hydroponically grown lettuce samples. This study indicated that hydroponically grown lettuce obtained at retail may have food safety risks similar to organic and conventional systems. These findings highlight the need for food safety training and educational programs.

Safety and Quality of Romaine Lettuce Accessible to Low Socioeconomic Populations Living in Houston, TX.

ABSTRACT: Previous empirical evidence has demonstrated that low-socioeconomic status (SES) communities have higher rates of gastroenteritis; however, there is a paucity of literature on the safety and quality of food (fresh produce) accessible to these communities. The overarching goal of this study was to investigate the microbial safety and quality of romaine lettuce from low- and high-SES neighborhoods in the Houston, TX, area. Loose-leaf romaine lettuce was purchased from low- and high-SES neighborhood retailers, and aerobic plate count, coliform, Escherichia coli, yeast, and mold assays were conducted. In addition, enrichment was performed on all samples for Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., and E. coli O157:H7, and reverse transcriptase PCR analysis was carried out. The results showed that E. coli, coliform, yeast, and mold were present in significantly higher counts (P < 0.05) in produce obtained from low-SES neighborhoods compared with high-SES neighborhoods. The reverse transcriptase PCR results showed that 38% of samples from high-SES areas were positive for S. aureus versus 87% of samples from low-SES areas. None of the samples from high-SES areas were positive for the other pathogens. The samples from low-SES areas were positive for E. coli O157:H7 (4%), Salmonella spp. (53%), L. monocytogenes (13%), and S. aureus (87%). These results demonstrate a significant disparity in the quality and safety of romaine lettuce accessible to low- versus high-SES populations. Future studies can be designed to identify the specific cause of this challenge by investigating the food supply chain.

Persistence of Foodborne Pathogens on Farmers' Market Fomites.

ABSTRACT: The number of farmers' markets registered by the U.S. Department of Agriculture has seen a significant increase, jumping from 1,755 in 1994 to 8,771 in 2019. Although previous studies have investigated the microbial profile of produce obtained from farmers' markets, literature exploring microbial (bacteria and virus) persistence on a variety of different farmers' market fomites over a 2-month period is limited. The objective of the current study was to investigate the persistence of key foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus, and MS2 bacteriophage) on these fomites by using a microbiological viability assay. The MS2 bacteriophage was quantified by using a host E. coli strain, and PFU were identified. A repeated measures analysis of variance was used to compare the persistence rates of foodborne pathogens on cardboard, plastic, tablecloth, molded pulp fiber, and wicker baskets used to store, transport, and display produce at farmers' markets. In general, molded pulp fiber, plastic, and wicker surface materials supported the persistence of foodborne pathogens the most, with Salmonella and S. aureus demonstrating the highest log concentrations over the longest period of time. Additionally, E. coli strains also persisted for a significant period of time on all fomites, with the exception of tablecloth. The results suggest that foodborne pathogens on these fomites pose a high risk of cross-contamination, particularly if the fomites cannot be washed, rinsed, and sanitized effectively (e.g., cardboard). The results highlight the need to avoid using porous, single-use storage containers, such as cardboard, molded pulp fiber, and wicker containers for extended periods of time and suggest the use of easily cleanable materials, such as plastic containers.

Retraction

The online ahead of print article titled "Assessing Food Safety Practices Among Texas Small Growers" by Zahra H. Mohammad, Isabelle do Prado, Rene Nieto, Richard De Los Santos, and Sujata A. Sirsat has been retracted by the authors and the Scientific Editors. The retraction is necessary because the study and its survey were conducted prior to Institutional Review Board (IRB) approval.

Comparison between the Real-Time PCR and Crystal Diagnostic Xpress Immunoassay Methods for Detecting Salmonella and Shiga Toxin-Producing Escherichia coli in the Air of Beef Slaughter Establishments.

ABSTRACT: The aim of this study was to compare the effectiveness of a quantitative real-time PCR (qPCR) molecular method and the Crystal Diagnostic Xpress (CDx) immunoassay for detecting Salmonella and Shiga toxin-producing Escherichia coli (STEC) in air samples collected from abattoirs in Texas. The 70 air samples were collected from two small and two large meat processing plants in the spring and summer with a wetted wall cyclone air sampler. The samples were divided equally into two parts: one part was used for the qPCR assay, and the other part was enriched for 18 and 36 h and evaluated with the CDx immunoassay. All samples for which positive results were obtained were confirmed by plating and by biochemical and serological tests as recommended by AOAC International to verify results of rapid methods. With the qPCR and CDx assays and 36 h of enrichment, 37.5 and 57.1% of the samples, respectively, were positive for Salmonella (P < 0.05) and 65.0 and 60.7%, respectively, were positive for STEC (P > 0.05). Air samples required longer enrichment for the CDx immunoassay than recommended by the manufacturer for food samples. Recovery of Salmonella and STEC increased 16 and 47%, respectively, when enrichment was extended from 18 to 36 h. The prevalence of Salmonella and STEC obtained with both methods was affected by the size of the processing plant and the processing stage. Detection rates for samples from larger plants were higher for both pathogens. Significantly higher prevalence was obtained for samples from the stunning and dehiding areas than for those from the fabrication rooms and chillers. Salmonella detection was higher with the CDx assay than with the qPCR assay, but no differences were found for the detection of STEC by the qPCR and CDx assays. These results highlight the importance of method adjustments when testing matrices other than foods. More research is needed to understand the dynamics of pathogen dispersal in aerosols and how this affects the effectiveness of current rapid detection methods.

Inactivation of Salmonella and Shiga toxin-producing Escherichia coli (STEC) from the surface of alfalfa seeds and sprouts by combined antimicrobial treatments using ozone and electrolyzed water.

Individual chemical and non-chemical treatments have failed to disinfect alfalfa seeds and sprouts from pathogens thoroughly. This study investigated the disinfection of alfalfa seeds and sprouts using a procedure combining ozone with acidic (pH 3.0) electrolyzed water (AEW). Inoculated alfalfa seeds with a cocktail of 3 strains Salmonella and 3 strains of STEC were treated sequentially with aqueous ozone followed by AEW. Treatment started by immersing the samples into ozonated water (5 mg/L ozone) for 15 or 20 min with persistent oxygen feeding pressurized with 10 psi. The samples then were immersed in 1 L of AEW for 15 min. Salmonella and STEC were significantly (P < 0.05) reduced by 3.6 and 2.9 log CFU/g on seeds respectively, and by 3.1 and 3.0 log CFU/g reduction on sprouts. Significant differences (P < 0.05) were found in the magnitude of the log reduction between Salmonella and STEC on seeds and between seeds and sprouts. Using combined treatments showed no significant changes in the quality, including shelf life, weight, and color in sprouts as compared to controls. The findings suggest that the combination of ozone and AEW is effective in inactivation of Salmonella and STEC on alfalfa seeds and sprouts with no adverse effects on sprouts quality.

Implications of Temperature Abuse on Unpasteurized Beer Quality Using Organoleptic and Chemical Analyses.

Beer flavor and sensory quality are affected by storage time and temperature due to chemical breakdown and aging. This study aimed to investigate the organoleptic properties of temperature-abused, unpasteurized craft beer and analyze the chemical breakdown associated with the process. Sensory tests were performed using a triangle test to determine consumer identification of temperature-abused beer. The chemical tests were conducted to determine the chemical breakdown of the two beer groups: control beer (COB) and temperature-abused beer (TAB). The chemical analysis of the two beer groups showed significant changes in multiple chemical compounds such as ethyl esters, linear aldehydes, and sulphur-compounds; however, the sensory analysis results were not significant even though 39% of participants were able to detect differences. in this study, two factors identified that caused chemical reactions in the TABs were oxidation and live yeast cells. In conclusion, these results can be used by beer producers to ensure a quality product throughout the distribution chain by controlling time and temperature.

Effect of post inoculation drying procedures on the reduction of Salmonella on almonds by thermal treatments.

Since two outbreaks of salmonellosis were linked to the consumption of almonds in 2001 and 2004, the study of pathogen inactivation kinetics in almonds has been encouraged, often by conducting inoculated challenge studies. The inoculation method could affect the results of such challenge studies, because of the possible increase of moisture on the almonds resulting from a wet inoculation procedure, which may result in a potential overestimation of the effectiveness of treatments used to pasteurize almonds in industrial settings. Salmonella enterica serotype Enteritidis phage type 30 (PT30) isolated from an almond-linked outbreak was inoculated on nonpareil almonds and dried by accelerated (drying the inoculated almonds at 37 °C for 12 h) and conventional (drying inoculated almonds overnight at room temperature) drying methods, before treating the almonds with hot water (blanching) at 88 °C or hot oil (oil roasting) at 127 °C. The Weibull model explained the death of this pathogen on almonds better than log-linear model for oil roasting, whereas both log-linear and Weibull models were similarly effective for blanching. For blanching, the D values for Salmonella Enteritidis PT30 were 12.7 and 10.7 s with accelerated and conventional drying, respectively. For oil roasting, the b-values were 4.59 and 4.18 s with accelerated and conventional drying, respectively. Based on the models, it was concluded that the accelerated drying process resulted in a significantly smaller reduction in Salmonella Enteritidis PT30 on almonds in comparison to conventional drying for both blanching and roasting. Although conventional drying led to significantly lower D or b - values (depending on the model), this difference is not likely to affect the current processing parameters used by the almond industry.

Food Safety Challenges and Barriers in Southern United States Farmers Markets.

Purchasing fresh and local produce at farmers markets has seen an increasing trend over the past decade. However, with this rise in popularity food safety challenges need to be recognized and addressed. Farmers market managers play a significant role in ensuring that vendors implement food safety practices at the market. Thus, this study investigated the food safety perceptions of farmers markets managers and vendors in Texas and Arkansas. A total of 123 participants were surveyed, including 38 managers and 85 vendors. The survey included a series of questions to determine gaps in vendor and manager food safety knowledge as well as the barriers and factors that prevent the implementation of relevant food safety practices. The results indicate that a lack of facilities, equipment, and resources containing food safety guidelines specific to farmers markets were the major barriers to the implementation of food safety practices. In addition, only 36.7% of participants had formal food safety training (e.g., ServSafe) and approximately 50% of the market managers provided food safety materials to their vendors. Overall, these data suggest that the development of farmers market-specific training programs to enhance food safety behaviors and practices in farmers markets would be beneficial to stakeholders.

Reduction of Salmonella and Shiga toxin-producing Escherichia coli on alfalfa seeds and sprouts using an ozone generating system.

Several outbreaks of illness have been associated with consumption of alfalfa sprouts contaminated with Shiga toxin-producing Escherichia coli (STEC) and Salmonella. The ozone application was investigated as an intervention. Alfalfa seeds were inoculated with cocktails of 3 Salmonella strains, including serotypes Typhimurium, Agona and Saintpaul, and 3 strains of Shiga toxin-producing Escherichia coli (STEC) including serotypes O104:H4, O157:H7 and O121:H19 with a final load of 7.0 log CFU/ml. Then, the inoculated seeds, and the sprouts obtained from these seeds were separately subjected to aqueous ozone treatment containing (5 mg/L) ozone for varied times of exposure. The mean log reductions for Salmonella achieved on seeds after 10, 15, and 20 min of ozone exposure were 1.6 ±â€¯0.5, 1.7 ±â€¯0.3, 2.1 ±â€¯0.5, respectively and 1.5 ±â€¯0.4, 1.6 ±â€¯0.4, 2.1 ±â€¯0.5 for STEC, respectively. For sprouts obtained from the inoculated seed, the mean log reductions for Salmonella after 10, 15, and 20 min exposure times were 0.7 ±â€¯0.2, 1.1 ±â€¯0.4, 3.6 ±â€¯0.2, respectively, whereas the mean log reductions for STEC were 0.7 ±â€¯0.1, 1.2 ±â€¯0.3 and 1.8 ±â€¯0.2, respectively. At each contact time, there were no differences in log reductions between pathogens on seeds (P > 0.05), whereas on sprouts, the reductions obtained at 20 min were significantly greater (P < 0.05) for Salmonella than for STEC. On both seeds and sprouts, the exposure time had significant (P < 0.05) effects on log reductions of Salmonella and STEC. The weight, color properties and shelf life of ozonated sprouts were also tested. The ozonation did not have negative effects on germination (%), color and mass of sprouts in comparison with the controls. This study confirmed that it is possible to substantially reduce Salmonella and STEC by using a low ozone concentration (5 mg/L) and reduce food safety risk with less concern about the safety for processing workers of this treatment, this without affecting seed germination. This procedure may be a promising intervention to reduce Salmonella and STEC from alfalfa seeds and sprouts.

Increased Effectiveness of Microbiological Verification by Concentration-Dependent Neutralization of Sanitizers Used in Poultry Slaughter and Fabrication Allowing Salmonella enterica Survival.

Sanitizer neutralizers can assist foodborne pathogen detection during routine testing by counteracting sanitizer residues carried over into fluids collected and tested from food samples. This study tested sanitizer-matched neutralizers applied at increasing concentrations to facilitate Salmonella enterica survival following exposure to cetylpyridinium chloride (CPC) or peracetic acid (PAA), identifying minimum required concentrations of neutralizers to facilitate pathogen survival. Salmonella isolates were individually inoculated into a non-selective medium followed immediately by CPC (0.1 to 0.8% v/v) or PAA (0.0125 to 0.2% v/v) application, followed by neutralizers application. CPC was neutralized by lecithin and polysorbate 80, each supplemented into buffered peptone water (BPW) at 0.125 to 2.0X its respective content in Dey-Engley (D/E) neutralizing buffer. PAA was neutralized in BPW supplemented with disodium phosphate, potassium monophosphate, and sodium thiosulfate, each at 0.25 to 3.0X its respective concentration in BPW (phosphates) or D/E buffer (thiosulfate). Addition of neutralizers at 1X their respective concentrations in D/E buffer was required to allow Salmonella growth at the maximum CPC concentration (0.8%), while 2X neutralizer addition was required for Salmonella growth at the maximum PAA level (0.2%). Sanitizer neutralizers can assist pathogen survival and detection during routine food product testing.