SUMMARY–The effects of adding 5 and 10 lactic culture(Streptococcus lactisandLeuconostoc citrovorum)grown in skim milk; 2.5, 5, 10, and 20 lactic cultures grown in 20 milk solids; 1 and 2 frozen concentrated lactic cultures; lactic acid to pH 5.0 and 4.5; and 2.5, 5, and 10 skim milk to ground beef stored at refrigeration temperature (7°C) were studied in the 6 preliminary trials. Results obtained were used to formulate the principal investigation. The influence of 10 lactic culture and 10 lactic culture plus 450 ppm of ascorbic acid were tested in 5 replicate trials for the principal investigation. Cultures used in the replicate trials were grown in 20 milk solids. CVT (crystal violet tetrazolium) counts for gram‐negative bacteria, pH, VNC (volatile nitrogen content), and organoleptic observations were evaluated. Data from the preliminary study indicated a profound inhibitory action of the lactic cultures on the growth of the inherent gram‐negative bacteria in ground beef. The addition of 10 lactic culture grown in 20 milk solids was effective in preventing aerobic growth. The addition of pure lactic acid inhibited microbial growth, butcausedan undesirable color and aroma. Frozen concentrated cultures required 1 lactose to inhibit the growth. The CVT count in the uncultured meat significantly increased (P<.01) as the storage time progressed. Cultured meat did not exhibit a significant increase in CVT count until 7 days of storage. The pH of the cultured meat significantly declined (P<.01) whereas the uncultured meat indicated a significant increase in pH (P<.01) during storage. VNC in the uncultured meat was significantly higher (P<.01) than in the cultured meat. Cultured meat with 450 ppm of ascorbic acid was consistently preferred for flavor, aroma, and when color was compared with the uncultured meat and the meat with culture
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