Use of novel lactic acid bacterial strains with antagonistic activity for the preparation of safe indigenous fermented dairy foods (Dahi and Raita).

Abstract

Attempts were made to isolate natural antagonistic lactic acid bacteria (LAB) and use them in production of dahi and raita for increased safety. Seventy isolates of LAB were isolated from dahi obtained from different sources. These isolates were tested for their antagonistic activity against selected pathogenic strains of Staphylococcus aureus subsp. aureus and Escherichia coli AB 1157 by adopting agar well assay method. Out of the 70 lactic acid bacterial isolates, 8 were found to have antagonistic activity against both pathogenic organisms. These isolates achieved the desired fermentation rate. Dahi produced by these isolates was found accept- able according to sensory evaluation. The LAB isolates with antagonistic activity were identified by molecular characterization. It is concluded that the identified antagonistic cultures were effective in inhibiting the growth of E. coli and Sta. aureus in dahi and raita.