Evaluation of isolated Lactobacillus strains as Probiotics in yogurt preparation

Background: Probiotics are live organisms that when ingested in adequate amount are believed to provide health benefits to the host. Probiotics are when combined with prebiotics are termed as synbiotics and in that case prebiotics enables the probiotic organisms to survive better in the host. The main objective of this study is to investigate Lactobacillus strains isolated from dairy products with significant probiotic potential and their utilization in yogurt preparation.Methods: Eleven (11) bacterial strains were identified as Lactobacillus by following Bergey’s manual scheme. Antibacterial activity was checked by agar well diffusion method. Their ability to grow at different bile salt concentration, pH concentration and in the presence of pepsin enzyme was checked under in vitro condition. Finally, they potential strains were evaluated as probiotic starter in yogurt preparation.Results: Out of total strains isolated, 52% strains were considered as Lactobacillus. Half of the strains (50%) showed antibacterial activity against selected pathogens and the best zone was formed by S4BM2 (15mm) against Salmonella typhi. All the isolated strains had the ability to grow in the presence of 0.2% bile salt concentration; at pH 3, pH5 and in the presence of pepsin enzyme. The efficacy of Lactobacilli strains as starter culture in yogurt was checked and found that yogurt processed with combination of S2Y2 with apple pieces showed significant results as compared to uninoculated yogurt.Conclusion: It was concluded that strain i.e. S2Y2 can further be used in different dairy industries for yogurt processing to improve the quality of yogurt.Keywords: Fermentation; Prebiotics; Probiotics; Synbiotics; Syneresis; Yogur