GROWTH AND SPORULATION POTENTIAL OF CLOSTRIDIUM-PERFRINGENS IN AEROBIC AND VACUUM-PACKAGED COOKED BEEF

Growth of Clostridium perfringens in aerobic- and anaerobic- (vacuum) packaged cooked ground beef was investigated. Autoclaved ground beef w as inoculated with approximately 3.0-log10 CFU/g of C perfringens, pac kaged and stored at various temperatures. Vegetative cells and heat-re sistant spores were enumerated by plating unheated and heated (75-degr ees-C for 20 min) meat samples on tryptose-sulfite-cycloserine agar. C lostridium perfringens grew to >7 logs within 12 h at 28, 37 and 42-de grees-C under anaerobic atmosphere and at 37 and 42-degrees-C under ae robic conditions. At 28-degrees-C under aerobic conditions, growth was relatively slow and total viable count increased to >6 logs within 36 h. Similarly, growth at 15-degrees-C in air was both slower and less than under vacuum. Regardless of packaging, the organism either declin ed or did not grow at 4, 8 and 12-degrees-C. Spores were not found at <12-degrees-C. Spores were detected as early as 8 h at 42-degrees-C un der anaerobic conditions, but in general, the type of atmosphere had l ittle influence on sporulation at greater-than-or-equal-to 28-degrees- C. Temperature abuse (28-degrees-C storage) of refrigerated products f or 6 h will not permit C perfringens growth. However, cyclic and stati c temperature abuse of such products for relatively long periods may l ead to high and dangerous numbers of organisms. Reheating such product s to an internal temperature of 65-degrees-C before consumption would prevent food poisoning since the vegetative cells were killed.