Shelf-Life Evaluation and Microbiological Quality Analysis of Dahi (Yogurt) Available in Local Market of Suddhowala, Dehradun, India

Abstract

The goal of the current investigation was to isolate and describe microorganisms from Dahi samples that were gathered from the Sudhowala area. Five different cultures were obtained by serial dilution, plating, and streaking five samples (Ananda, Paras, Heritage, Good Health, and Local). The microbial characteristics, biochemical characterization, Gram staining, and colony morphology determined using microbiological standard methods. Ananda was the only isolate that was Gram-positive; the others were all Gram-negative. All isolates tested positive for catalase, oxidase, methyl red, Voges-Proskauer, and citrate, but negative for coagulase, according to biochemical tests. Studies conducted over seven days at different temperatures (0, 10, and 20 degrees Celsius) showed that as temperature and storage time increased, titratable acidity and total plate count increased while pH decreased. Using a 9-point hedonic scale, sensory evaluation revealed that fresh samples' color, flavour, and aroma were generally acceptable; however, overall acceptability dramatically declined with extended storage, especially at higher temperatures. Differences in milk sources, handling, and processing may be reason for variations in microbial activity and product quality. The results emphasize how crucial ideal storage conditions are for guaranteeing Dahi's microbiological safety and sensory appeal for consumer acceptance.