Christina M. Moore

Transfer of Salmonella and Campylobacter from Stainless Steel to Romaine Lettuce

The degree of transfer of Campylobacter jejuni and Salmonella enterica serovar Typhimurium was evaluated from a stainless steel contact surface to a ready-to-eat food (lettuce). Stainless steel coupons (25 cm2) were inoculated with a 20-microl drop of either C. jejuni or Salmonella Typhimurium to provide an inoculum level of approximately 10(6) CFU/28 mm2. Wet and dry lettuce (Lactuca sativa var. longifolia) pieces (9 cm2) were placed onto the inoculated stainless steel surface for 10 s after the designated inoculum drying time (0 to 80 min for C. jejuni; 0 to 120 min for Salmonella Typhimurium), which was followed by the recovery and enumeration of transferred pathogens (lettuce) and residual surface pathogens (stainless steel coupons). For transfers of Salmonella Typhimurium to dry lettuce, there was an increase from 36 to 66% in the percent transfer of the initial inoculum load during the first 60 min of sampling and then a precipitous drop from 66 to 6% in percent transfer. The transfer of Salmonella Typhimurium to wet lettuce ranged from 23 to 31%, with no statistically significant difference between recoveries over the entire 120-min sampling period. For C. jejuni, the mean percent transfer ranged from 16 to 38% for dry lettuce and from 15 to 27% for wet lettuce during the 80-min sampling period. The results of this study indicate that relatively high numbers of bacteria may be transferred to a food even 1 to 2 h after surface contamination. These findings can be used to support future projects aimed at estimating the degree of risk associated with poor handling practices of ready-to-eat foods.

Consumer knowledge, storage, and handling practices regarding Listeria in frankfurters and deli meats : Results of a web-based survey

Proper storage and handling of refrigerated ready-to-eat foods can help reduce the risk of listeriosis. A national Web-based survey was conducted to measure consumer awareness and knowledge of Listeria and to estimate the prevalence of the U.S. Department of Agriculture-recommended consumer storage and handling practices for frankfurters and deli meats. The demographic characteristics of consumers who are unaware of Listeria and who do not follow the recommended storage guidelines were also assessed. In addition, predictive models were developed to determine which consumers engage in risky storage practices. Less than half of the consumers surveyed were aware of Listeria, and most of those aware were unable to identify associated food vehicles. Awareness was lower among adults 60 years of age and older, an at-risk population for listeriosis, and individuals with relatively less education and lower incomes. Most households safely stored and prepared frankfurters. Most households stored unopened packages of vacuum-packed deli meats in the refrigerator within the U.S. Department of Agriculture-recommended storage guidelines (< or =14 days); however, many stored opened packages of vacuum-packed deli meats and freshly sliced deli meats for longer than the recommended time (< or =5 days). Men, more-educated individuals, and individuals living in metropolitan areas were more likely to engage in risky storage practices. This study identified the need to develop targeted educational initiatives on listeriosis prevention.

Consumer-phase Salmonella enterica serovar enteritidis risk assessment for egg-containing food products

We describe a one-dimensional probabilistic model of the role of domestic food handling behaviors on salmonellosis risk associated with the consumption of eggs and egg-containing foods. Six categories of egg-containing foods were defined based on the amount of egg contained in the food, whether eggs are pooled, and the degree of cooking practiced by consumers. We used bootstrap simulation to quantify uncertainty in risk estimates due to sampling error, and sensitivity analysis to identify key sources of variability and uncertainty in the model. Because of typical model characteristics such as nonlinearity, interaction between inputs, thresholds, and saturation points, Sobols method, a novel sensitivity analysis approach, was used to identify key sources of variability. Based on the mean probability of illness, examples of foods from the food categories ranked from most to least risk of illness were: (1) home-made salad dressings/ice cream; (2) fried eggs/boiled eggs; (3) omelettes; and (4) baked foods/breads. For food categories that may include uncooked eggs (e.g., home-made salad dressings/ice cream), consumer handling conditions such as storage time and temperature after food preparation were the key sources of variability. In contrast, for food categories associated with undercooked eggs (e.g., fried/soft-boiled eggs), the initial level of Salmonella contamination and the log10 reduction due to cooking were the key sources of variability. Important sources of uncertainty varied with both the risk percentile and the food category under consideration. This work adds to previous risk assessments focused on egg production and storage practices, and provides a science-based approach to inform consumer risk communications regarding safe egg handling practices.

Identification of Core Competencies for an Undergraduate Food Safety Curriculum Using a Modified Delphi Approach.

Identification of core competencies for undergraduates in food safety is critical to assure courses and curricula are appropriate in maintaining a well-qualified food safety workforce. The purpose of this study was to identify and refine core competencies relevant to postsecondary food safety education using a modified Delphi method. Twenty-nine experts representing food safety professionals in academia, government, and industry were given 2 rounds of questionnaires that specified initial food safety competencies, core domains, and subdomains. Competencies were defined as a set of skills, knowledge, and abilities that correlate to success of a trainee. The framework for which competencies were classified consisted of (1) core domains, defined as broad food safety subjects; and (2) subdomains, or more specific food safety subjects. The expert panel used a 5-point Likert scale with an acceptance criterion, or consensus, of 75%, with a rating of “4” or greater. After 2 rounds of questionnaires and revisions from the expert panel, 5 core domains were established: (1) Food Production, Manufacturing, Retail, and Consumer; (2) Foodborne Hazards; (3) Public Health; (4) Legislation and Policy; and (5) Communication and Education. Specific responses from the experts highlighted areas in which further curriculum revision would be beneficial. This study provides a framework for the development of a vetted, standardized undergraduate food safety curriculum. The Delphi method, with its inclusion of professionals representing various sectors of food safety, provided relevant perspectives for curriculum design, and also allowed participants the opportunity to contribute to the education of future food safety professionals.

Use of time-temperature integrators and predictive modeling to evaluate microbiological quality loss in poultry products.

The purpose of this study was to characterize the kinetics of the spoilage process of chicken drumsticks in order to evaluate the application of an enzyme process-based time-temperature integrator (TTI) as a continuous quality monitor of poultry products. Shelf life studies were conducted at several temperatures (3 to 20 degrees C) to characterize (i) the poultry spoilage process as a function of total aerobic bacteria and Pseudomonas species populations and (ii) the TTI chroma response function. Two types of poultry products were examined: ice-packed and chill-packed drumsticks. An enzyme-based TTI with a color change response from green to yellow was used. Activation energies for each of the poultry products and each of the bacterial populations were as follows: 21.8 +/- 1.6 kcal/mol (ca. 91.2 +/- 6.7 kJ/mol) for ice-packed drumsticks and total aerobic population, 18.8 +/- 4.5 kcal/mol ca. 78.7 +/- 18.8 kJ/mol) for ice-packed drumsticks and Pseudomonas spp., 17.0 +/- 2.3 kcal/mol (ca. 71.1 +/- 9.6 kJ/mol) for chill-packed drumsticks and total aerobic population, and 14.1 +/- 3.6 kcal/mol (ca. 59.0 +/- 15.1 kJ/mol) for chill-packed drumsticks and Pseudomonas spp. The activation energy calculated for the TTI, 19.1 +/- 1.8 kcal/mol (ca. 79.9 +/- 7.5 kJ/mol), was determined to be adequately close to that of the poultry spoilage process to make effective quality predictions possible. Initial bacteria levels on the chicken drumsticks were uniform and not judged as important limiting factors in the application of TTIs to poultry products. Because the poultry spoilage process was reasonably characterized on the basis of Arrhenius kinetics, there is further need to conduct validation studies to determine the ability of TTIs to provide a continuous quality monitoring system.

Evaluation of time-temperature integrators for tracking poultry product quality throughout the chill chain.

The goal of this study was to evaluate the application of one type of time-temperature integrator (TTI) to monitor the microbiological quality of ice-packed raw chicken drumsticks as a function of temperature exposure. A kinetics-based model was used to correlate the TTI chroma response to the number of bacteria on the drumstick surface under constant- and variable-temperature conditions. Two constant-temperature studies (4 and 15 degrees C) and one variable-temperature study (4 degrees C for 24 h, 15 degrees C for 24 h, 4 degrees C constant) were conducted to evaluate the applicability of the TTI under ideal and worst-case situations. During the constant-temperature studies, quality predictions made at the midpoint of the product shelf life were accurate within 15% for the observed bacterial populations. The accuracy of the TTI was marginal in the initial and final stages of the response period. During the variable-temperature study, the TTI response demonstrated positive history effects, whereby the observed rate constant is affected by previous temperature exposure. After the TTIs had been held at 15 degrees C for 24 h, the TTI response rate constant observed during subsequent storage at 4 degrees C was higher than what would be predicted for 4 degrees C. Further work will be needed to develop a continuous TTI-based quality monitoring system. However, because the microbiological quality of fresh poultry could be reliably predicted with kinetic models, fresh poultry products would be excellent candidates for a TTI-based quality monitoring system.

Content Analysis of Vomit and Diarrhea Cleanup Procedures To Prevent Norovirus Infections in Retail and Food Service Operations

Human noroviruses are the leading cause of foodborne disease in the United States, sickening 19 to 21 million Americans each year. Vomit and diarrhea are both highly concentrated sources of norovirus particles. For this reason, establishing appropriate cleanup procedures for these two substances is critical. Food service establishments in states that have adopted the 2009 or 2013 U.S. Food and Drug Administration Food Code are required to have a program detailing specific cleanup procedures. The aim of our study was to determine the alignment of existing vomit and diarrhea cleanup procedures with the 11 elements recommended in Annex 3 of the 2011 Supplement to the 2009 Food Code and to determine their readability and clarity of presentation. In July 2015, we located vomit and diarrhea cleanup procedures by asking Norovirus Collaborative for Outreach, Research, and Education stakeholders for procedures used by their constituency groups and by conducting a Google Advanced Search of the World Wide Web. We performed content analysis to determine alignment with the recommendations in Annex 3. Readability and clarity of presentation were also assessed. A total of 38 artifacts were analyzed. The mean alignment score was 7.0 ± 1.7 of 11 points; the mean clarity score was 6.7 ± 2.5 of 17 points. Only nine artifacts were classified as high clarity, high alignment. Vomit and diarrhea cleanup procedures should align with Annex 3 in the Food Code and should, as well, be clearly presented; yet, none of the artifacts completely met both conditions. To reduce the spread of norovirus infections in food service establishments, editable guidelines are needed that are aligned with Annex 3 and are clearly written, into which authors could insert their facility-specific information.