Omega-3 Eggs Research Articles

GROWTH, SURVIVAL AND HEAT RESISTANCE OF SALMONELLA TYPHIMURIUM AND ESCHERICHIA COLI IN REGULAR AND OMEGA‐3 HENS EGG PRODUCTS

ABSTRACT Omega‐3 enriched eggs are currently produced by hens fed a flax diet. Since omega‐3 polyunsaturatedfatty acids are prone to oxidation, the addition of vitamin E is supplemented into the hen's diet as an antioxidant. Typically these eggs contain about 2 and 4 times more omega‐3 fatty acids and vitamin E, respectively compared to regular eggs. Since table eggs have a long history of association with foodborne salmonellosis, it was of interest to compare the growth and/or survival of several bacterial pathogens in omega‐3 and regular eggs. In this respect nalidixic‐resistant Escherichia coli and Salmonella Typhimurium were inoculated into regular and omega‐3 hen's egg products (whole eggs, albumen, yolk) and incubated at 22, 8 and −20C. Time‐course studies indicated that by 72 h both Salmonella and E. coli levels increased by 7 logs at 22C in both types of whole egg. At 8C population levels for these bacteria both increased by approximately 3 logs at 6 weeks. In regular and omega‐3 yolks, salmonellae maintained at 22 and 8C for 48 h and 6 weeks increased by approximately 6 and 1.5 logs, respectively. E. coli levels were higher in egg yolk compared to Salmonella at both temperatures. Regardless of the yolk source, however, no significant (P > 0.05) differences in population levels were observed. Survival patterns of E. coli at −20C were not significantly (P > 0.05) different between whole egg sources. This trend was also observed in the yolks. For Salmonella no significant (P > 0.05) differences in survival were observed between yolk preparations maintained at −20C. Increasing the level of α‐tocopherol from c. 63 to 240 ppm in regular egg yolk, resulted in no significant (P > 0.05) differences in the growth of Salmonella at 22C. In addition, when the bacterium was heated in regular egg yolk amended with vitamin E at 56.5C, no significant (P > 0.05) difference was observed in resistance regardless of α‐tocopherol (55‐713 ppm) or total tochopherol (92–1238 ppm) level.