REDUCING MICROBIAL POPULATIONS ON BEEF TISSUES: CONCENTRATION AND TEMPERATURE OF LACTIC ACID

Cylindrical samples of beef semitendinosus muscle were dipped in inocula of diluted (1:8) fresh bovine manure or suspensions of Escherichia coli or Salmonella typhimurium. After air drying 15 min, samples were sanitized by dipping in lactic acid(0, 1, 2 or 3%)for 15 s at 25, 40, 55 or 70°C. The most effective treatment was dipping the lean beef muscle in 3% lactic acid solution at 70°C. In general, as the temperature of acid at each concentration was increased from 25 to 70°C, numbers of surviving test organisms were increasingly reduced. Overall, concentration was an insignificant variable at the higher temperatures but became significant as temperature was lowered. Treatment tended to affect aerobes most and E. coli least. Bacterial injury was shown to be a factor to be considered when conducting sanitizing studies.