Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Food Technology

Committee Chair/Advisor

Dawson, Paul L.

Committee Member

Falta , Debbie

Committee Member

Jiang , Xiuping

Committee Member

Northcutt , Julie K.


The specialty foods market has grown by 30% since 2006 with specialty eggs now making up about 5% of all eggs sold at retail. Specialty eggs like those produced in alternative production systems and enhanced in beneficial nutrients can provide a profitable opportunity for egg producers while meeting consumer demands for nutritious, safe, and humanely-produced eggs. Isoflavone-enriched eggs can be marketed as a new specialty egg that would offer a valuable source of health-promoting isoflavones, nutrients that are typically lacking in diets of Western culture. Equol, a potent soy isoflavone is found naturally in eggs of laying hens and can be enhanced by adding soy germ to the laying hen diet. If produced in a free-range production system, this kind of specialty egg would appeal to both nutrition-conscious and animal welfare-conscious consumers while increasing farmer profitability and sustainability. To determine the potential for producing an equol-enriched, free-range specialty egg, the present study was conducted to measure the equol content, nutrient content, and microbiological characteristics of eggs produced from hens fed varying amounts of soy in a free-range and conventional production system. Eighty-four Bovan Brown chicks were randomly assigned to free-range or conventional production systems and fed parallel diets of standard soy, soy enhanced, or soy-free laying hen feed formulations for 2, 4 week experimental feeding trials. Eggs were collected and analyzed for equol, amino acid, fatty acid, and cholesterol content at hen ages 20, 23, 24, and 27 weeks old. Eggshells were also rinsed and crushed for the determination of total aerobic microorganisms, Enterobacteriaceae spp., Salmonella spp., and Campylobacter spp. Eggs were compared for differences based on production system, age and diet treatment. Eggs from hens fed a soy enhanced diet were significantly higher in equol concentration than eggs from hens fed a standard soy or soy-free diet. No differences were detected in amino acid or cholesterol levels of eggs, however small, but statistically different concentrations of some fatty acids were detected. Levels of Enterobacteriaceae spp., Salmonella spp., and Campylobacter spp. were higher in free-range eggs from hens fed any of the three diet treatments than conventionally produced eggs. Results support the potential for producing an equol-enriched, free-range egg that is comparable in amino acid, fatty acid, and cholesterol composition to their conventional counterparts. However, if produced in a free-range production system, measures must be taken to minimize contamination levels of pathogens on the eggs by washing eggs with organically approved sanitizers and detergents.

Included in

Food Science Commons



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