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United States Department of Agriculture

Agricultural Research Service

2009 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
Differences in microbial populations associated with the environment and eggs from sister flocks of laying hens housed in cages and on range was completed. The study was conducted through 80 weeks of hen age, sampling every 6 weeks during production. Growth patterns were completed for Yersinia enterocolitica in 4 liquid egg products with University of Tasmania collaborators. At temperatures between 10 and 37oC, numbers of Y. enterocolitica increased over time in whole egg, sugared egg, and albumen. In whole egg and sugared yolk at 4oC, the organism grew well but slowly. Less robust growth was noted in albumen. Y. enterocolitica was unable to grow in salted yolk at any temperature tested.

Enterobacteriaceae isolates from eggs, the air, and biofilms of equipment and the environment in a shell egg washing facility were examined via biochemical tests in an automated system to identify genera or species. Biofilm isolates of Salmonella were serotyped and analyzed by repetitive Enterobacteriaceae palindrome polymerase chain reaction.

Efficacy of a sanitizer system for Salmonella decontamination was assessed. After 5 minutes, almost 99.9% of Salmonella on stainless steel surfaces and 99% on packer head brushes (99.999% overnight) were killed.

Inoculation studies were conducted on the microcrack detection system to determine if eggs were more likely to have contaminated contents if Salmonella was present on the shell surface before imaging. Recovery of Salmonella from inoculated imaged eggs was not different than inoculated control eggs and negative control eggs did not become infected with Salmonella via cross contamination in the system.

The effect of the microcrack detection system on broiler breeder egg hatchability was determined with University of Georgia collaborators on eggs from both high and low quality production. The microcrack detection system did not affect hatchability.

Collaborative research with the Eastern Regional Research Center determined thermal death rates of various Salmonellae in egg yolk during pasteurization. Physical quality characteristics of egg products were also monitored.

The role of a hatching egg sealant on physical quality and hatchability was examined. The use of the egg coating has the potential to expand the capabilities of primary breeders to ship hatching eggs for commerce.

Detergents formulated for cleaning shell eggs with cooler wash water were compared to a traditional detergent used at warmer temperatures. New cool water detergents were as effective as the traditional temperature and detergent in decreasing numbers of aerobic microorganisms and Enterobacteriaceae.

Eggs were collected from sister flocks housed in traditional cages or aviary style pens. Neither Salmonella nor Campylobacter were recovered from eggs. Levels of aerobic microorganisms and Enterobacteriaceae were very low for eggs from either flock after washing.

1. Determining the diversity of naturally occurring microflora associated with free range and caged produced shell eggs. Eggs produced alternatively from traditional caged egg production have begun to be more common in retail due to consumer demand. A long-term study was completed which examined the diversity of naturally occurring microflora in the laying environment, the shell matrix and the egg contents throughout a 60 week production cycle. Gaining an understanding of the differences in microbial populations present on and within eggs from traditional and free range production will allow retail free range eggs to be of equivalent microbial quality via targeted processing to reduce naturally occurring organisms.

5.Significant Activities that Support Special Target Populations
Assessing the naturally occurring microbial flora associated with free range egg production will allow for the many small farms producing these eggs to enhance their product safety. Results will provide insight on seasonal changes in microbial populations and the effect of laying environment on egg microbial safety. The results can also function as a baseline for developing rodent and pest control programs in free range production.

6.Technology Transfer

Number of New Patent Applications Filed1

Review Publications
Kawasaki, T., Musgrove, M.T., Murata, M., Tominaga, N., Kawamoto, S. 2008. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs. Journal of Food Safety. 28:482-498.

Lawrence, K.C., Yoon, S.C., Jones, D.R., Heitschmidt, G.W., Park, B., Windham, W.R. 2009. Modified Pressure System for Imaging Egg Cracks. Transactions of the ASABE. 52(3):983-990.

Musgrove, M.T., Mcquestin, O.J., Tamplin, M., Kelley, L.C. 2009. Growth and survival of antibiotic-resistant Salmonella Typhimurium DT104 in liquid egg products. Journal of Food Protection, 72:1992-1996.

Last Modified: 11/28/2015
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