BACTERIAL-GROWTH IN-GROUND BEEF PATTIES MADE WITH MEAT FROM ANIMALS FED DIETS WITHOUT OR WITH SUPPLEMENTAL VITAMIN-E

A study was designed to determine populations of aerobic bacteria, col iforms, sorbitol-negative bacteria, and Listeria monocytogenes during display at 4 and 12 degrees C of ground beef patties made with meat fr om animals fed diets supplemented daily (for 100 days) with 0, 1,000, or 2,000 IU of vitamin E. The patties (113.5 g) were either left unino culated or were inoculated with Escherichia coli O157:H7 or L. monocyt ogenes and were tray-ovens rapped and stored (at 4 or 12 degrees C for 8 to 10 or 4 to 6 days, respectively) while being continuously expose d to fluorescent light in a display setting. Patties were visually eva luated for overall appearance (based on color and/or discoloration) tw ice a day and analyzed for microbiological counts st 2-day intervals d uring display at 4 degrees C and at 0, 1, 2, 3, 4, and 6 days during d isplay at 12 degrees C. Use of beef from animals fed supplemental vita min E (''high-vitamim E beef'') resulted in ground beef patties which, when stored at 4 degrees C, maintained visually acceptable color long er than did patties made from control beef (from animals not fed suppl emental vitamin E), but effects on microbial growth were less pronounc ed. In general, use of high-vitamin E beef versus control beef in patt y manufacture had no major effect on populations of aerobic bacteria, coliforms, sorbitol-negative bacteria, or L. monocytogenes in ground b eef potties displayed at 4 or 12 degrees C. Listeria monocytogenes mul tiplied at 12 degrees C, but growth was similar among ground beef patt ies made from high-vitamin E beef versus control beef. Overall, change s in bacterial populations were similar in ground beef patties derived from meat from animals with or without added vitamin E in their diets , but control ground beef became visually unacceptable sooner.