Evaluation of Market Curd for Sanitary Quality and Bacteriocin- Producing Lactic acid Bacteria for Potential Application as a Natural, Healthy Food Preservative

The quality of curd in local market varies as there are no well described standards for milk products, making evaluation of their microbiological quality, important. Curd is a great source of lactic acid bacteria, important producers of bacteriocins (proteinaceous antimicrobials). The study evaluates curd samples, collected from local market of Jalandhar, for sanitary quality and presence of bacteriocin-producing lactic acid bacteria (LAB). Of the total 21 curd samples tested, only 14% showed confluent microbial growth and categorized as 'poor quality' in terms of microbial load. Sample 6 exhibited best sanitary quality. 3 isolates (LABI, II, and III), of the total of 42 bacterial colonies tested, were promising bacteriocin producers against Vibrio parahemolyticus and E.coli with, LABIII (17357 U mL ^-1) as the best bacteriocin producer, exhibiting 13.1% higher activity than standard reference, Lactococcous lactis subspecies lactis MTCC440, against E.coli. LABI and II showed similar bacteriocin activity against V. parahemolyticus while, against E.coli, bacteriocin activity was 7539 U mL ^-1 and 10995 U mL ^-1 for LABI and II, respectively. The future work will explore efficiency of LABIII as biopreservative in different food materials in cost effective manner. This would help to provide economic solutions for food preservation with distinct and well proved health benefits for the consumers.