Investigation of the usability of commercially available industrial kefir in homemade kefir production

In this study, the potential of producing homemade kefir from commercially available kefir drinks was investigated. For this purpose, two different brands of kefir, which are the most widely sold in the market, were used. Microbial growth kinetics, viscosity and pH were monitored during the fermentation process of kefir samples. During fermentation, lactobacilli, lactococci, total mesophilic aerobic bacteria (TMAB) counts and viscosity values increased while pH values decreased. The regeneration study was completed by successive passaging of the kefirs produced for 4 days. Microorganism counts did not show significant changes during passaging steps. The presence of yeast in the samples produced from brand B kefir could not be observed after the 3rd passaging. Storage analyses were performed on the 1st, 7th, 14th, 21th and 28th days of storage. At the end of the storage period, lactobacilli, lactococci and TMAB counts decreased in both brands, while yeast counts did not change for brand B kefir. Viscosity values and serum separation increased in both brands, while pH values decreased. In sensory analyses, panelist tastes were higher on the 21th day of storage for brand A and on the 7th day for brand B. No statistical difference was observed in dry matter content, titratable acidity, L* and a* values during storage (p>0.05). As a result of the study, it was observed that it is possible to produce commercial kefir beverages if the necessary hygiene conditions and incubation temperature are observed.