EFFECT OF GROWTH OF SELECTED LACTIC-ACID BACTERIA ON STORAGE LIFE OF BEEF STORED UNDER VACUUM AND IN AIR

The effect of growth of different types of lactic acid bacteria (LAB) on the storage life of normal pH beef was determined anaerobically (un der vacuum) and aerobically. Four LAB from meat were inoculated separa tely onto sterile slices of lean beef. Inoculated samples were stored anaerobically at 2 degrees C for 10 weeks or stored aerobically in an oxygen permeable film at 7 degrees C for 10 days, with and without pre vious storage under vacuum at 2 degrees C. The LAB strains used were C arnobacterium maltaromicus (previously C. piscicola) LV17 and UAL26, L euconostoc gelidum UAL187-22 and Lactobacillus sake Lb706. Storage lif e was determined by sensory panel evaluation of colour and odour. Unde r anaerobic conditions Lb. sake Lb706, inoculated at log 2 CFU/cm(2), grew rapidly to reach maximum population within three weeks of storage . L. gelidum UAL187-22 also grew on the meat but at a slower rate. In contrast, growth of C. maltaromicus LV17 and UAL26 was unpredictable, achieving maximum population after 2 to 8 weeks. None of the test stra ins caused spoilage of the meat within the 10-week storage period unde r vacuum. When the test organisms were inoculated at an initial level of log 4 CFU/cm(2), C. maltaromicus LV17 and UAL26 produced off-odours after 8 weeks of storage under vacuum at 2 degrees C. Under aerobic c onditions at 7 degrees C, all four of the strains grew well on the bee f samples. C. maltaromicus LV17 and UAL26 and Lb. sake Lb706 all cause d off-odours and discoloration. The rate of aerobic deterioration in m eat quality was faster with increased time of storage under vacuum. L. gelidum UAL187-22 could be a suitable antagonistic strain with the po tential to extend the storage life of beef, stored anaerobically and p ackaged aerobically for retail sale, without producing undesirable sen sory changes.