EFFECT OF DEGREE OF VACUUM AND LENGTH OF STORAGE ON THE MICROFLORA OF VACUUM PACKAGED BEEF WHOLESALE CUTS

Abstract

ABSTRACT Wholesale cuts of fresh beef were vacuum packaged at low, intermediate or high degrees of vacuum and stored at l‐3°C for 7, 14, 21, 28 or 35 days. Bacterial counts of samples after 7 and 14 days of storage were low [mean count < 10 4 per in. 2 (6.45 cm 2 )] irrespective of degree of vacuum. Lactobacilli and anaerobic agar plate counts of cuts stored under high vacuum for 21‐35 days tended to be lower than those of comparable cuts stored under low or intermediate vacuum. This was also true, but much less frequently, for the psychrotrophic and mesophilic counts. Largest increases in bacterial counts occurred between 14 and 21 days of storage. Fluorescent pseudomonads represented only a small percentage of the total microbial population of vacuum packaged beef cuts. Lactobacilli and anaerobic plate counts of vacuum‐packaged cuts were very similar. The psychrotrophic bacterial population of cuts stored for 28 days consisted primarily of Lactobacillus sp., while Pseudomonas sp. and Enterobacteriaceae represented only a small percentage of the psychrotrophic microflora at that time.