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ABSTRACT:
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 bio-preservative 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.
KEYWORDS: curd, lactic acid bacteria, bacteriocin, food preservation, health benefits.
INTRODUCTION:
A variety of pathogenic organisms may reach milk and milk products like, curd and contribute towards a variety of food borne illnesses. Milk and milk products may carry toxic metabolites of different organisms growing in it. Ingestion of such products, contaminated with these metabolites, cause food poisoning. On the other hand, the ingestion of microbial pathogens along with the food product leads to food borne infection1. The quality of curd in local market varies from shop to shop and poor quality milk, unhygienic practices associated with the process involved, and the use of wild type of starter cultures, give rise to poor grade curd2.
Evaluation of the microbiological quality of milk products is thus, an important task and numerous attempts have been made by researchers worldwide to check milk and milk products including, curd for their microbiological quality3-4. Apart from the presence of pathogenic microorgansisms, milk and milk products have also been characterized for...