IMPROVEMENT IN MICROBIOLOGICAL QUALITY AND SHELF-LIFE OF BUFFALO MEAT AT AMBIENT TEMPERATURE BY GAMMA IRRADIATION

The effect of low dose gamma-irradiation (2.5 kGy) on the shelf-life of prepacked fresh buffalo meat at ambient temperature (28–30C) in terms of microbiological, chemical and sensory qualities was studied. Unirradiated samples initially showed the presence of Enterobacteriaceae and Staphylococcus spp. These gradually increased during storage. After 12 h of holding , Clostridium spp. were observed in these samples. On the basis of microbiological, chemical and sensory analyses, the shelf-life was limited to 18 h. In contrast , Clostridium spp. and Enterobacteriaceae were not detected in irradiated samples throughout the storage period and Staphylococcus spp. were detected only after 12 h of holding. Irradiated samples had a shelf-life of 42 h.     

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

The 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.     

THE ELIMINATION OF ENTERIC BACTERIAL PATHOGENS FROM FOOD AND FEED OF ANIMAL ORIGIN BY GAMMA IRRADIATION WITH PARTICULAR REFERENCE TO SALMONELLA RADICIDATION1

Despite world-wide severe underreporting of food-transmitted disease of microbial origin, it is clear that the majority of such diseases is caused by enteropathogenic Enterobacteriaceae. Most of these are spread by foods of animal origin, consumed raw, or recontaminated subsequent to industrial or culinary heat processing. Radicidation with the help of gamma rays of carcasses or consumer size cuts presents a real solution to this problem. An ecologically based procedure for the estimation of the most probable effective dose for the elimination of enteric pathogens of bacterial origin from fresh meats, poultry and seafoods is described, special attention being paid to bacteriological analytical methodology found useful under conditions of practice. An additional advantage of this approach is, that it will allow easy assessment of lower doses, following reductions of initial enterobacterial loads, which should be attempted in parallel. It is demonstrated that most alleged counter-indications so far hampering the use of ionizing radiation in food processing have now been eliminated, allowing full advantage to be derived from radicidation as an essential contribution to the protection of the consumer against diseases of microbial aetiology spread by foods, similar to the mandatory pasteurization of milk.