Fermentation process of mulberry juice-whey based Tibetan kefir beverage production

Abstract

Mixture of mulberry juice and whey was evaluated as a potential substrate for the production of a beverage by Tibetan kefir grains. Different mulberry juice addition was used. Acidity, pH, volatile flavour compounds as well as microbial communities were determined during 40 h of fermentation at 18°C. Gas chromatography-mass spectroscopy (GC-MS) analysis revealed that ethanol and 3-methyl-1-butanol were dominant alcohols, and ethyl caprylate, ethyl caprate, ethyl acetate and ethyl caproate were the most dominant ester compounds. The microbial communities of fermented beverage were close to kefir grains indicating that they had similar microbial communities gradually during the fermentation process. Lactococcus was frequently detected at the beginning and then Lactobacillus rapidly proliferated after acclimatizing to the fermentation environment. Acetobacter was steadily increasing during the fermentation process. For the fungi, Candida was frequently detected with the highest abundances in almost all samples.