Bacteriocins are natural metabolites produced by many strains of Lactic acid bacteria that used in food
bioprocessing. They have potential healthy role in suppressing the growth of some spoilage and pathogenic
bacteria. Bacteriocin from Lactobacillus acidophilus strain was extracted and inoculated into freshly pasteurized
milk at concentrations of 320, 160, 80 & 40 IU/mL, then the milk samples were examined for T.A% &
microbiological examination at the time of preparation and at 3 days intervals till sings of spoilage were detected.
Obtained results revealed that pasteurized milk samples with bacteriocin at concentration 160 and 320 IU/mL
showed the lowest T.A% & highly significant inhibitory effect on total bacterial count, aerobic spore formers and
psychrotrophic count, as well as it could extend the shelf-life of pasteurized milk up to 12 days during refrigerator
storage. While, for those samples with 80 IU/mL showed no effect on both total bacterial count & psychrotrophic count with slight reduction for aerobic spore formers. While, those with 40 IU/mL & control ones (without bacteriocin) could not control the bacterial contaminant counts and the signs of spoilage appeared at the 9th day of
storage.