The effect use of different incubation temperature and different final incubation pH on physicochemical, microbiological, sensorial and probiotic properties of acidophilus yoghurt

In this study, probiotic yoghurt was manufactured by using yoghurt starter culture, probiotic bacteria (Lactobacillus acidophilus ATCC 4356) and different incubation temperatures and final incubation pH?s. The yoghurt samples were stored at 4°C for 30 days, and physicochemical, microbiological, sensorial and probiotic properties of the yoghurts were determined on day 1, 15 and 30 of the storage. At the final stage of the storage period; the counts of Lactobacillus debrueckii spp. bulgaricus, Streptococcus thermophilus and L. acidophilus in the samples decreased; in contrast syneresis, hardness and viscosity of the samples increased. At the end of the storage, antimicrobial activity, antibiotic sensitivity, bacterial adhesion, gastric juice and bile resistance of probiotic bacteria in the samples decreased. Based on the results of sensory analysis, the sensory properties of the samples decreased during the storage. Regarding appearance and consistency, and odour and taste the yoghurt sample incubated at 45°C until pH 4.6 and the yoghurt sample incubated at 37°C until pH 4.4 were more preferred, respectively.