Effects of antioxidants and gamma irradiation on the shelf life of beef patties

To improve the storage safety of two types of ground beef patty popular in Korea (general beef patties and bulgogi patties), we added various antioxid ants (200 ppm; including butylated hydroxyanisole, ascorbyl palmitate, alph a-tocopherol, and beta-carotene) to typical formulations of patties, cooked the patties to 70 degrees C, and irradiated them at a dose of 1.5 or 3 kGy . During 30 d of storage at 5 degrees C, the number of aerobic bacteria and lactic acid bacteria were determined using total aerobic plate count and p henyl ethyl alcohol-sucrose agar, respectively. The concentration of thioba rbituric acid was also determined in each type of patty. No colonies were o bserved in patties irradiated at 3 kGy regardless of which antioxidant was added. In control patties and patties with butylated hydroxyanisole that we re irradiated at a dose of 1.5 kGy, growth of microorganisms appeared to be more rapid than in patties with natural antioxidants. The microbiological safety of nonirradiated patties could not be ensured for a period of 20 d. Lipid oxidation was retarded in both types of patty when an antioxidant was added; Ascorbyl palmitate had the strongest antioxidant effect among the n atural antioxidants. However, butylated hydroxyanisole was more effective t han ascorbyl palmitate when used in an equal amount.