Antagonistic effect of developed probiotic yoghurt against some selected food-borne pathogens during cold storage

This study was carried out to investigate the antagonistic effect of probiotic yoghurt against some selected food-borne pathogens during cold storage. Probiotic yoghurt was produced from processed cow milk using controlled fermentation, and later inoculated with selected food-borne pathogens at inoculum level of 10⁵ CFU/mL. The antagonistic effect of the probiotic yoghurt against the food-borne pathogens during cold storage (4^oC) for 2 days was studied using standard methods. The results obtained demonstrated that the probiotic yoghurt inhibited growth of food-borne pathogens including Salmonella typhimuriumATCC13311, Proteus mirabilis ATCC25933, and Escherichia coliATCC2592 in the yoghurt within 24 hr. Their counts decreased from 10⁵-10² CFU/mL, with pH and probiotic counts ranging between 4.48-4.35, and 10⁶-10⁸ CFU/mL, respectively. The probiotic bacteria have the ability to suppress the growth of pathogen like E. coli in yoghurt. This inhibitory effect may be due to low pH of yoghurt. The probiotic cultures in the yoghurt can be used as biopreservatives in food and pharmaceutical industries.