Food Safety Exam Phrasing for Food Service Employees.

In many jurisdictions foodservice workers are required to obtain food handler certification via written examination before being able to work. This study investigated the effect of the readability, or the ease in which one can read and comprehend written text, of food handler exam questions on exam performance. It was hypothesized that the reduction in cognitive load by improving the readability of exam questions would lead to improved scores. Participants received training in personal hygiene and basic food safety and were tested on their knowledge using questions that were worded using the traditional phrasing and updated phrasing that has improved readability. The results indicate that improved readability had a significant difference in the personal hygiene section but not on the basic food safety section. These results are due, in part, to the types of cognitive load (intrinsic vs. extraneous) that are required to solve different types of problems.

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.

Consumers' Knowledge and Handling Practices Associated with Fresh-Cut Produce in the United States.

Previous studies have shown that three factors influence fresh-cut produce safety from farm to fork: (1) post-harvest practices in processing facilities, (2) employees' handling practices in retail facilities, and (3) consumers' handling practices in domestic kitchens or cooking facilities. However, few studies have examined consumers' food safety knowledge, risk perceptions, and their handling practices associated with fresh-cut produce. To fill this gap, the present study conducted a nationwide survey to assess U.S. consumers' food safety knowledge, practices, and risk perception associated with fresh-cut produce among various demographic groups and investigated factors influencing consumers' food safety practices related to fresh-cut produce. The results showed that consumers lack the knowledge and safe handling practices toward fresh-cut produce regarding storage hierarchy, surface cleaning and sanitizing, and time and temperature control of fresh-cut produce. The men and millennial consumers exhibit a lower level of safe fresh-cut produce handling practices. In addition, a significant interaction was observed between food safety knowledge and risk perceptions on consumers' fresh-cut produce handling practices, such that food safety knowledge can transfer to practice more effectively for consumers with high levels of risk perception. The results can be utilized to design effective consumer food safety education tools for targeted audiences.

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.

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.

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.

How Clean Are Hotel Rooms? Part I: Visual Observations vs. Microbiological Contamination.

Current evidence of hotel room cleanliness is based on observation rather than empirically based microbial assessment. The purpose of the study described here was to determine if observation provides an accurate indicator of cleanliness. Results demonstrated that visual assessment did not accurately predict microbial contamination. Although testing standards have not yet been established for hotel rooms and will be evaluated in Part II of the authors' study, potential microbial hazards included the sponge and mop (housekeeping cart), toilet, bathroom floor, bathroom sink, and light switch. Hotel managers should increase cleaning in key areas to reduce guest exposure to harmful bacteria.

How Clean Are Hotel Rooms? Part II: Examining the Concept of Cleanliness Standards.

Hotel room cleanliness is based on observation and not on microbial assessment even though recent reports suggest that infections may be acquired while staying in hotel rooms. Exploratory research in the first part of the authors' study was conducted to determine if contamination of hotel rooms occurs and whether visual assessments are accurate indicators of hotel room cleanliness. Data suggested the presence of microbial contamination that was not reflective of visual assessments. Unfortunately, no standards exist for interpreting microbiological data and other indicators of cleanliness in hotel rooms. The purpose of the second half of the authors' study was to examine cleanliness standards in other industries to see if they might suggest standards in hotels. Results of the authors' study indicate that standards from other related industries do not provide analogous criteria, but do provide suggestions for further research.

A strategic cleaning assessment program: menu cleanliness at restaurants.

The importance of clean food contact surfaces has been recognized; however, the importance of cleanliness on nonfood contact surfaces such as menus may be underestimated. The aim of the study described in this article was to determine the cleanliness of restaurant menus, evaluate typical cleaning methods used in a restaurant, and provide recommendations for improving menu cleanliness. The authors' study used an adenosine triphosphate meter to assess the cleanliness of the menus. A pretest identified the most commonly touched areas of the menu by consumers. Based on the results of the pretest, menus were collected from casual-family dining restaurants and analyzed for cleanliness. Results suggested that menus should be cleaned after each shift and that menus distributed by the staff when guests are seated are cleaner than those kept on the table.

Tracking microbial contamination in retail environments using fluorescent powder--a retail delicatessen environment example.

Cross contamination of foodborne pathogens in the retail environment is a significant public health issue contributing to an increased risk for foodborne illness. Ready-to-eat (RTE) processed foods such as deli meats, cheese, and in some cases fresh produce, have been involved in foodborne disease outbreaks due to contamination with pathogens such as Listeria monocytogenes. With respect to L. monocytogenes, deli slicers are often the main source of cross contamination. The goal of this study was to use a fluorescent compound to simulate bacterial contamination and track this contamination in a retail setting. A mock deli kitchen was designed to simulate the retail environment. Deli meat was inoculated with the fluorescent compound and volunteers were recruited to complete a set of tasks similar to those expected of a food retail employee. The volunteers were instructed to slice, package, and store the meat in a deli refrigerator. The potential cross contamination was tracked in the mock retail environment by swabbing specific areas and measuring the optical density of the swabbed area with a spectrophotometer. The results indicated that the refrigerator (i.e. deli case) grip and various areas on the slicer had the highest risk for cross contamination. The results of this study may be used to develop more focused training material for retail employees. In addition, similar methodologies could also be used to track microbial contamination in food production environments (e.g. small farms), hospitals, nursing homes, cruise ships, and hotels.

Persistence of Salmonella and E. coli on the surface of restaurant menus.

To the authors' knowledge, the role of restaurant menus as a vehicle for pathogens has not been explored. Menus, however, can pose as a vector for bacterial contamination and transfer. Sampling menus from two restaurants in the Houston, Texas, area showed the presence of up to 100 CFU/cm2 aerobic bacteria. Follow-up studies designed to investigate the ability of Salmonella and E. coli to persist on paper and laminated menus at various time points (0, 6, 24, 48, and 72 hours) demonstrated that bacteria persist more efficiently on laminated menus as compared to paper menus. Transfer studies performed to quantitatively determine the ability of bacteria to transfer from menus to fingertips and from fingertips to clean menus showed that bacteria can be transferred for up to 24 hours. The study described here showed that restaurant menus may serve as vehicles for pathogens and hence present a public health issue within the retail food environment.

Microbial Profile of Soil-Free versus In-Soil Grown Lettuce and Intervention Methodologies to Combat Pathogen Surrogates and Spoilage Microorganisms on Lettuce.

Aquaponics is an effective method to practice sustainable agriculture and is gaining popularity in the US; however, the microbial safety of aquaponically grown produce needs to be ascertained. Aquaponics is a unique marriage of fish production and soil-free produce (e.g., leafy greens) production. Fish are raised in fresh water tanks that are connected to water filled beds where fruits and vegetables are grown. The fish bi-products create nutrient-rich water that provides the key elements for the growth of plants and vegetables. The objective of this study was to perform a comparative analysis of the microbial safety and quality of aquaponic lettuce and soil grown lettuce (conventional, bagged, certified organic, and field lettuce). Following this, an intervention study was performed to combat foodborne pathogen surrogates (Salmonella and E. coli), spoilage, and fecal microorganisms using 2.5% acetic acid. The results of the comparative analysis study showed that aquaponically grown lettuce had significantly lower concentration of spoilage and fecal microorganisms compared to in-soil grown lettuce. The intervention study showed that diluted vinegar (2.5% acetic acid) significantly reduced Salmonella, E. coli, coliforms, and spoilage microorganisms on fresh lettuce by 2 to 3 log CFU/g. Irrespective of growing methods (in-soil or soilless), it is crucial to incorporate good agricultural practices to reduce microbial contamination on fresh produce. The intervention employed in this study can be proposed to small farmers and consumers to improve quality and safety of leafy greens.

Optimization of the RNA extraction method for transcriptome studies of Salmonella inoculated on commercial raw chicken breast samples.

BACKGROUND: There has been increased interest in the study of molecular survival mechanisms expressed by foodborne pathogens present on food surfaces. Determining genomic responses of these pathogens to antimicrobials is of particular interest since this helps to understand antimicrobial effects at the molecular level. Assessment of bacterial gene expression by transcriptomic analysis in response to these antimicrobials would aid prediction of the phenotypic behavior of the bacteria in the presence of antimicrobials. However, before transcriptional profiling approaches can be implemented routinely, it is important to develop an optimal method to consistently recover pathogens from the food surface and ensure optimal quality RNA so that the corresponding gene expression analysis represents the current response of the organism. Another consideration is to confirm that there is no interference from the "background" food or meat matrix that could mask the bacterial response. FINDINGS: Our study involved developing a food model system using chicken breast meat inoculated with mid-log Salmonella cells. First, we tested the optimum number of Salmonella cells required on the poultry meat in order to extract high quality RNA. This was analyzed by inoculating 10-fold dilutions of Salmonella on the chicken samples followed by RNA extraction. Secondly, we tested the effect of two different bacterial cell recovery solutions namely 0.1% peptone water and RNAprotect (Qiagen Inc.) on the RNA yield and purity. In addition, we compared the efficiency of sonication and bead beater methods to break the cells for RNA extraction. To check chicken nucleic acid interference on downstream Salmonella microarray experiments both chicken and Salmonella cDNA labeled with different fluorescent dyes were mixed together and hybridized on a single Salmonella array. Results of this experiment did not show any cross-hybridization signal from the chicken nucleic acids. In addition, we demonstrated the application of this method in a meat model transcriptional profiling experiment by studying the transcriptomic response of Salmonella inoculated on chicken meat and exposed to d-limonene. We successfully applied our method in this experiment to recover the bacterial cells from the meat matrix and to extract the RNA. We obtained high yield and pure RNA. Subsequently, the RNA was used for downstream transcriptional profiling studies using microarrays and over 600 differentially regulated genes were identified. CONCLUSIONS: Our result showed that 8 log cfu/g of Salmonella is ideal to obtain optimal RNA amount and purity. Our results demonstrated that RNAprotect yielded higher RNA amounts (approximately 10 to 30 fold) when compared to 0.1% peptone water. The differences between the RNAprotect and 0.1% peptone samples were significant at a p-value of 0.03 for the bead beater method and 0.0005 for the sonication method, respectively. The microarray experiment demonstrated that the chicken samples do not interfere with the hybridization of Salmonella cDNA on the array slide. Hence, the background chicken RNA will not interfere with the microarray analysis when poultry meat models are used. Finally, we successfully demonstrated the application of the poultry meat model proposed in this study by conducting transcriptional profiling analysis of Salmonella inoculated on the poultry. Results of this study proved that this method has the potential to be employed in other meat model studies.

Escherichia coli, an Intestinal Microorganism, as a Biosensor for Quantification of Amino Acid Bioavailability.

In animal diets optimal amino acid quantities and balance among amino acids is of great nutritional importance. Essential amino acid deficiencies have negative impacts on animal physiology, most often expressed in sub-optimal body weight gains. Over supplementation of diets with amino acids is costly and can increase the nitrogen emissions from animals. Although in vivo animal assays for quantification of amino acid bioavailability are well established, Escherichia coli-based bioassays are viable potential alternatives in terms of accuracy, cost, and time input. E. coli inhabits the gastrointestinal tract and although more abundant in colon, a relatively high titer of E. coli can also be isolated from the small intestine, where primary absorption of amino acids and peptides occur. After feed proteins are digested, liberated amino acids and small peptides are assimilated by both the small intestine and E. coli. The similar pattern of uptake is a necessary prerequisite to establish E. coli cells as accurate amino acid biosensors. In fact, amino acid transporters in both intestinal and E. coli cells are stereospecific, delivering only the respective biological l-forms. The presence of free amino- and carboxyl groups is critical for amino acid and dipeptide transport in both biological subjects. Di-, tri- and tetrapeptides can enter enterocytes; likewise only di-, tri- and tetrapeptides support E. coli growth. These similarities in addition to the well known bacterial genetics make E. coli an optimal bioassay microorganism for the assessment of nutritionally available amino acids in feeds.