Microbial Growth on Fat and Lean Surfaces of Vacuum‐Packaged Chilled Beef

Brochothrix thermosphacta, Enterobacteriaceae and the Pseudomonas‐Moraxella group grew more rapidly on the fat than on the lean surfaces of chilled vacuum‐packaged beef striploins of pH 5.45–5.85. On the fat, both B. thermosphacta and Enterobacteriaceae grew to outnumber the Pseudomonas‐Moraxella. When Enterobacteriaceae and B. thermosphacta were present initially in about equal numbers, Enterobacteriaceae outgrew B. thermosphacta on both the fat and the lean surfaces of packs stored at 5°C. At 1°C the growth rate of the Enterobacteriaceae was greatly reduced. As a result, on the fat at 1°C, B. thermosphacta grew considerably faster than did the Enterobacteriaceae.