INFLUENCE OF ANTIMICROBIAL COMPOUND(S) EXTRACTED FROM MILK FERMENTED BY STREPTOCOCCUS THERMOPHILUS ON KEEPING QUALITY OF MEAT AND MILK

Abstract

ABSTRACTThe potential of a methanol‐acetone (M‐A) extract prepared from milk fermented by Streptococcus thermophilus in extending the shelf‐life of meat and milk was investigated. In experiment I, increasing amounts (0, 0.1, 0.2 and 0.3 ml) of M‐A extract with or without ascorbic acid were added to 20 g aliquots of ground beef subsequently stored at 5–7° C for 0, 3 and 6 days. Total and gramnegative bacterial counts and pH in ground beef treated with M‐A extract were significantly (P<0.01) less than the corresponding values in control beef on days 3 and 6 for all dose levels tested with significant (P<0.01). In experiment II, rib‐eye steaks were sprayed with H2O or 0.1, 0.2 and 0.3 ml of M‐A extract and stored at 5–7° C for 0, 3 and 6 days. The total and gram‐negative bacterial counts on the surface of steaks sprayed with M‐A extract were significantly (P<0.01) lower than the counts in control steaks. Also, in experiment III, inhibition of bacterial growth by M‐A extract was significant (P<0.01 or 0.05) both in milk stored at either room temperature or 5–7° C. M‐A extract inhibited the growth of Pseudomonas fluorescens inoculated into milk.