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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
There are 3 objectives for the project emphasizing food safety, quality, and security of shell eggs and egg products. First, to evaluate post-processing sanitizers and sanitizing technologies for their benefits to the microbiological safety and quality of shell eggs. Second, to develop technologies and/or techniques to improve processing plant sanitation practices. Third, to develop, evaluate and validate rapid detection methods for pathogens and toxins (for example: Staphylococcus aureus and staphylococcal enterotoxins, Listeria, Vibrio and Yersinia species) which could compromise food security in egg products, including liquid egg.

1b.Approach (from AD-416)
The five year project plan for the Egg Safety, Quality and Security ARS Research Program will address issues of concern for the shell egg and egg products industry, regulatory personnel, allied industry and consumers. Emphasis will be placed on determining the role post-processing shell surface sanitizers play in product safety and quality. Novel compounds as well as application technologies will be examined. Furthermore, processing plant sanitation will be more thoroughly assessed to determine points where interventions could increase sanitation program effectiveness. Procedures will include evaluating equipment surfaces for improved cleaning methods. This will be of particular interest for both regulators and the industry with the advent of new processing regulations. With the recent importance of food security, rapid detection techniques for potential biological terror pathogens that could be introduced into liquid egg product will be evaluated. Through this objective, a greater understanding of intercepting potential agricultural threats will be gleaned. This project plan encompasses a large body of work that will result in safer, higher quality shell eggs and egg products for the consumer.

3.Progress Report
Studies were conducted to determine the effects of post-washing shell surface sanitizers on the physical and microbial quality of shell eggs during extended cold storage. The extended cold storage covered the maximum allowable time for shell eggs to be in the US retail market. Four chemical compounds were compared to unwashed eggs and washed, water-rinsed controls. The findings from this research will be transferred to commercial application for further examination.

Liquid egg products are sold as consumer products and utilized in the production of many bakery and convenience items. Sampling methods were developed for liquid whole egg, high whip albumen, 10% sugared yolk and 10% salted yolk due to their predominance in the egg products market. Salmonella Typhimurium was utilized to monitor sampling methods due to its known growth pattern in these products. The findings from this research will be transferred for the assessment of identified food security organisms.

Previous research conduct by this project has identified key areas of shell egg processing sanitation that need improvement. Equipment detergents and sanitizers have been explored and identified for their potential application advantages in the shell egg processing environment. Furthermore, sampling schemes have been developed for targeted bacterial populations. Subsequent studies will be conducted to determine the effectiveness of these compounds on cleaning commercial vacuum loader cups.

Seven types of retail shell eggs were examined for the presence of Enterobacteriaceae. The eggs represented the spectrum of consumer options for retail shell eggs. A total of 205 isolates were identified. The information gained from this research can be utilized for consumer education on safe handling of eggs and also by the industry to target microbial populations during processing.

Vitelline membrane strength has been identified as important for both physical and microbial egg quality. Static compression tests were conducted comparing four testing rigs. It was determined that some rigs were not as suitable for vitelline membrane strength assessment. Furthermore, the findings can be transferred to processors and breeders to assess vitelline membrane strength in a manner more targeted for their process or selection parameters.

There are regional consumer preferences for yolk color. A study was conducted to determine the variability in yolk color amongst several breeds of hens from a single laying flock. Yolk color was found to be highly variable within each strain indicating that precise control of yolk color could be difficult to achieve.

Scientists on this project participated in collaborative research with several other research units. A study was conducted to determine dielectric properties of eggs during storage and the correlation of these measurements with egg physical quality. Another project assessed shell surface sanitizers on hatching egg surface microbiology. Furthermore, assistance was provided during the development of imaging technology to assess shell eggs for micro-cracks in grading lots.

Shell surface sanitizer effects on shell egg physical quality: A post-processing shell surface sanitizing rinse is required by USDA-AMS for all USDA grade shielded shell eggs. Four potential sanitizing compounds were compared to water-rinsed processed eggs and unwashed eggs for their effect of egg physical quality during five weeks of cold storage. No significant differences in physical quality were seen between the treatments during the course of the study. The results of this research show that the use of a post-processing sanitizing rinse, including water, during egg processing affects no changes in egg physical quality compared to unwashed eggs and could be eliminated when considering egg physical quality factors. This research addresses National Program 108 (Food Safety), Component 1.2 (Pathogens, Toxins, and Chemical Contaminants - Postharvest), Problem Statement 1.2.4 (Processing Strategies and Interventions).

Application of post-processing shell surface sanitizers on the presence of microbial populations: Post-processing shell surface sanitizers have been required by USDA-AMS to help reduce the presence of spoilage organisms, not pathogens, on the shell surface. The recommended sanitizer approved by USDA-AMS has been 100-200 ppm chlorine. Four compounds were compared water-rinsed and unwashed eggs for their ability to reduce microbial populations associated with the shell and egg contents. Total aerobic organisms, Enterobacteriaceae, yeasts and molds and Salmonella were monitored within the shell matrix and in the egg contents during extended cold storage. The act of washing the eggs had the greatest affect on reducing microbial populations associated with the shell matrix. The various sanitizing compounds did exhibit a great change in bacterial load compared to water-rinsed washed eggs which could lead to revisiting the need for the post-processing shell sanitizing rinse requirement. This research addresses National Program 108 (Food Safety), Component 1.2 (Pathogens, Toxins, and Chemical Contaminants - Postharvest), Problem Statement 1.2.4 (Processing Strategies and Interventions).

5.Significant Activities that Support Special Target Populations

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings18

Review Publications
Jones, D.R. 2007. Changes in functional characteristics and quality factors of shell eggs during long-term storage. International Journal of Poultry Science.6:157-162.

Jones, D.R., Musgrove, M.T., Caudill, A.B., Curtis, P.A. 2006. Frequency of salmonella, campylobacter, listeria, and enterobacteriaceae detection in commercially cool water washed shell eggs. Journal of Food Safety.26:264-274.

Musgrove, M.T., Jones, D.R., Northcutt, J.K., Cox Jr, N.A., Harrison, M.A., Cray, P.J., Ladely, S.R. 2006. Antimicrobial resistance in salmonella and escherichia coli isolated from commercial shell eggs. Poultry Science. 85:1665-1669.

Last Modified: 8/27/2015
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