Effect of Various Types of Vacuum Packages and Length of Storage on the Microbial Flora of Wholesale and Retail Cuts of Beef

Abstract

Wholesale cuts of beef (knuckles, ribs, chucks) were vacuum packaged in three types of packages with oxygen transmission rates (cc/100 in.²/24 h) of 0.41–0.75, 1.09, and 2.28. One type of package was sealed with a clip; the others were heat sealed. Wholesale cuts were stored for 0–35 days at 1–3 C and retail cuts from ribs and knuckles were observed under retail conditions for 5 days. Differences in psychrotrophic, mesophilic, and lactobacillus counts of knuckles and ribs resulting from differences in type of package usually were not statistically significant. Differences in psychrotrophic counts of retail steaks of knuckles and ribs resulting from differences in type of package used for the primal cuts were not significant. Psychrotrophic and mesophilic counts of cuts in defective packages (leakers) increased faster than those of cuts in intact packages. The initial microbial flora of knuckles, ribs, and chucks consisted primarily of Moraxella-Acinetobacter spp. and coryneform bacteria. During the first few weeks of storage at 1–3 C Lactobacillus spp. already were dominant on knuckles and Microbacterium and Lactobacillus spp. predominated on ribs. After 28–35 days of storage Lactobacillus spp. were dominant on both knuckles and ribs. The microbial population on chucks after 21 days of storage consisted of Lactobacillus, Microbacterium, Enterobacteriaceae. Pseudomonas, Moraxella-Acinetobacter spp. and coryneform bacteria. The microflora of cuts from defective packages was comprised of species of Pseudomonas, Microbacterium, Lactobacillus, and Moraxella-Acinetobacter.