Microbial flora of commercially produced vacuum packaged, cooked beef roast

Abstract

Commercially produced vacuum packaged, fully cooked, microwaveable beef roasts from four producers were purchased from local retail markets. Salt concentration, pH, water activity (aw), and percent moisture, fat and protein were determined. Samples of both package juice and homogenized beef plus juice were analyzed for the presence of aerobic, anaerobic and lactic acid bacteria and clostridia-type organisms. The cooked beef products had pH values from 5.82 to 6.19, water activity of 0.992 to 0.997, and contained 0.34 to 1.07% salt, 61.89 to 72.39% moisture, 4.29 to 18.21% fat and 15.92 to 20.62% protein. No growth was detected in juice for aerobic, anaerobic or lactic acid bacteria or clostridia-type organisms. Combined beef and juice had less than 2 CFU/g for aerobic, anaerobic or lactic acid bacteria or clostridia-type organisms. Cooking and chilling schedules used in the manufacture of the four products we evaluated in this study limited survival and outgrowth of microorganisms.