Incidence and Spoilage Potential of Isolates from Vacuum‐packaged Meat of High pH Value

Meat of high pH value (6·6) showing dark‐cutting characteristics was vacuum‐packaged and stored for up to 8 weeks at 0–2°C. ‘Off’‐odours were detected on opening the packages after 6 weeks of storage. Total counts at this stage were ca. 10 7 /cm 2 of which lactobacilli were the major component, with ca. 10 6 /cm 2 Gram negative organisms. Psychrotrophic Enterobacteriaceae represented a major proportion of the microflora only after the full 8 weeks of storage and were not detected previously. Aerobic storage of steaks cut from the vacuum packaged meat stored for 8 weeks resulted in a predominantly Gram negative spoilage flora. Inoculation studies on meat of normal pH value (5·4) and appearance using representative isolates from the vacuum‐packaged meat microflora indicated that most of the test organisms were capable of causing spoilage under aerobic conditions but few under vacuum‐packaging when incubated at 4°C. On meat of higher pH value (6·15) many of the Gram negative isolates did not grow as well, whereas the Gram positive isolates grew better than on meat of normal pH value when held under aerobic conditions. Under vacuum‐packaging all but one isolate grew as well or better on meat of high pH value than on normal meat at 4°C and objectionable odours were more marked.