Isolation and Identification of Lactic Acid Bacteria from Traditional Fermented Milk “Dahi” Towards Developing Probiotic Dahi in Bangladesh

Abstract

Objective: An attempt was made herein to isolate lactic acid bacteria (Lactobacillus sp. and Streptococcus thermophilus) from local Dahi to develop Dahi with isolated culture. Methods: These bacteria were identified by morphological characteristics, microscopic observation, catalase reaction, and finally examined by Polymerase Chain Reaction (PCR). Five Dahi samples (T1, T2, T3, T4, and T5) were prepared using the PCR culture. Dahi samples (T1, T2, and T3) were prepared using three Lactobacillus sp., T4 by Streptococcus thermophilus, and T5 by a combination of Lactobacillus sp. (T3) and Streptococcus thermophilus (T4) bacteria. Physicochemical, microbiological, and sensory properties were measured to assess the quality of the developed Dahi. The shelf life of the products was assessed through the determination of pH and titrable acidity of the samples measured on day 1 and 7, respectively. Results: Ash and protein percentage of T3 sample were significantly (P<0.05) better than others. The viable count was well above the minimum recommended value (106cfu/ml) in all the Dahi samples. Results of sensory properties namely taste, aroma, and overall acceptability of T3 and T4 Dahi were significantly (P<0.05) found superior compared to other samples. Conclusion: The lactic acid bacteria isolated and utilized in this study demonstrate great potential in the production of probiotic Dahi in future.