microbial properties evaluation of a yogurt whey-based orange beverage fermented with kombucha as a starter culture

Background: this study aimed to evaluate microbial counts of beverage samples fermented using kombucha, including total acetic acid bacteria (aab), total lactic acid bacteria (lab), yeasts, and total microbial count (tmc).methods: a fermented orange beverage was produced using yogurt whey at three different concentrations (0 %, 10 %, and 20 % v/v) and kombucha at four different concentrations (1 %, 2 %, 3 %, and 4 % w/v) as the starter culture. next, the microbial counts of the produced samples were evaluated at the end of the incubation and during cold storage at 4 ℃. the results were expressed as log cfu/ml.results: the results indicated a significant increase in the viability of aab, tmc, and yeasts with increasing yogurt whey concentrations in the samples (p < 0.05).  furthermore, increasing the kombucha percentage in beverage samples resulted in the viability increment of tmc, aab, lab, and yeasts. over time, the number of yeasts and viability of lab increased in the samples. moreover, the viability of tmc and aab increased in the samples from days 7 to 10 and decreased from days 10 to 14 (p < 0.05).conclusion: increasing yogurt whey and kombucha percentages affect microbial counts of beverage samples fermented using kombucha.