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United States Department of Agriculture

Agricultural Research Service

2010 Annual Report

1a.Objectives (from AD-416)
There are 4 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. Fourth, to examine differences in microbial flora associated with the eggs from alternative agriculture practices.

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. Agricultural production practices have become more diverse to meet consumer demands. The microbial flora of eggs from alternative production will be compared to traditional production to gain a better understanding of their potential impact on egg safety.

3.Progress Report
An in-plant study was conducted to assess egg grades assigned by a USDA professional grader alone and one utilizing a modified pressure microcrack detection system. The professional graders assessed the same 3000 eggs. The grader utilizing the modified pressure microcrack detection system had a much greater accuracy in assessing USDA shell egg grades but use of the system increased grading time approximately five minutes per 100 egg sample set compared to the grader alone.

A study was undertaken to compare results from three modern shell quality assessment methods for both white and brown shell retail eggs. Dynamic stiffness (non-destructive measure of resonance properties of the shell) was monitored before and after exposure to a modified pressure microcrack detection system. Finally, shell strength (destructive measure of the amount of force required to crack the shell) was determined on each egg. No strong correlations existed amongst any of the measures. Dynamic stiffness readings were not altered due to eggs being exposed to the modified pressure microcrack detection system. As a portion of a study examining the role of Salmonella Enteritidis inoculation on hen health and egg production, shell quality was assessed. Dynamic stiffness, the presence of microcracks in the shells and shell static compression strength were monitored. Assessments were conducted three times a week for approximately five weeks. Complete data analysis is being conducted.

A study examining the effects of conventional cage, cage free barn and free range egg production on environmental and egg microbiology for a single strain of brown egg laying hens was initiated. The study follows the research flocks for an entire production cycle (approximately 80 weeks of age). All hens are housed on the same commercial-style research facility and receive an identical laying hen diet. Egg shells and contents, as well as environmental swabs, are enumerated for aerobic and gram negative bacteria, plus yeasts and molds. The presence of Salmonella, Campylobacter, and Listeria is also determined. The results from this study will be utilized to develop best practices for alternative egg producers to ensure product safety.

A similar study was initiated to compare three strains of brown egg laying hens housed in conventional cages, cage free barn and free range egg production systems through 80 weeks of age. Aerobic organisms, Enterobacteriaceae and yeast and molds associated with the egg shells and associated membranes are enumerated. The shell emulsions are also being assessed for the presence of Salmonella, Campylobacter and Listeria. The results of this study will be analyzed to determine if the strain of laying hen affects the microbiological characteristics of eggs from various production systems. Large and small egg producers can use this information to enhance the safety of eggs from various production environments. Preliminary experiments to analyze inoculated egg shell/membrane slurries and liquid eggs were performed using an automated system with Salmonella-coated magnetic beads. Further study is needed to determine the feasibility of the technology for egg use.

1. Development of a modified pressure microcrack detection system for use with shell eggs. While the device has an extremely high rate of accuracy (99.6 %), up to this point, it has not been tested in a truly commercial application. When two USDA Agricultural Marketing Service egg graders assessed the quality of same 3000 eggs, the grader utilizing the modified pressure microcrack detection system more accurately determined the overall grade of the eggs (according to USDA grade standards). While using the microcrack detection system did increase grading time approximately five minutes per set of 100 eggs, the increased overall accuracy could lead to more time between grading lots. Professional egg graders utilizing the modified pressure microcrack detection system during grading will increase both the safety and quality of eggs reaching consumers.

5.Significant Activities that Support Special Target Populations
Research on microbial populations associated with alternative egg production methods will assist small egg producers in the U.S. The research will provide small producers with technical information which will allow them to make informed decisions which can lead to eggs of enhanced safety and quality.

Review Publications
Jones, D.R. 2010. Shell Egg Vacuum Loader Cup Microbiological and Physical Quality Changes Associated with the Use of Various Sanitizing Compounds. Poultry Science. 89:564-569

Jones, D.R., Musgrove, M.T., Anderson, K.E., Thesmar, H.S. 2010. Physical Quality and Composition of Retail Shell Eggs. Poultry Science. 89:582-587

Caudill, A.B., Curtis, P.A., Anderson, K.E., Kerth, L.K., Oyarazabal, O., Jones, D.R., Musgrove, M.T. 2010. The Effects of Commercial Cool Water Washing of Shell Eggs on Haugh Unit, Vitelline Membrane Strength, Aerobic Microorganisms and Fungi. Poultry Science. 89:160-168

Jones, D.R., Lawrence, K.C., Yoon, S.C., Heitschmidt, G.W. 2010. Modified Pressure Imaging for Egg Crack Detection and Resulting Egg Quality. Poultry Science. 89:761-765.

Cox Jr, N.A., Richardson, L.J., Musgrove, M.T. 2010. Campylobacter jejuni, other campylobacters. Chapter 3 In Pathogens and Toxins in Foods: Challenges and Interventions. P.20-30.

Sommers, C.H., Sites, J.E., Musgrove, M.T. 2010. Ultraviolet light (254 NM) inactivation of pathogens on foods and stainless steel surfaces. Journal of Food Safety. 30(2):470-479.

Yoo, B., Stewart, T.E., Guard, J.Y., Musgrove, M.T., Gast, R.K., Chen, J. 2010. Selection and Characterization of Cellulose Deficient Mutants of Shiga Toxin Producing Escherichia coli. 2010. Applied and Environmental Microbiology. 73:1038-1046.

Last Modified: 8/27/2015
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