The effect of adding ewe's cheese whey on the quality of kefir drink

Kefir is a common drink in the Central Asian region and it has beneficial effects in improving the health of consumers. The aim of this study was to investigate the effect of adding different ewe's cheese whey to kefir drink on the survival rate of microorganisms of kefir including Lactobacilli, Lactococci and yeast. After the preparation of kefir drink, the ratio of 0, 5, 7.5 and 10% ewe's cheese whey was added to kefir drink. The samples were stored in the refrigerator and acidity, pH, number of Lactobacilli, Lactococci, and yeast were determined at 1, 7, 14, 21, and 28 days. The results of the study showed that the highest number of Lactobacilli on 14th and 21th days was 9.32 ± 30.0 and 9.23 ± 0.30 log cfu/ml, respectively. The highest number of Lactococci in the control and kefir samples contained 7.5% whey on 21th day was 10.42 ± 0.17 log cfu/ml. The highest number of yeast in samples have 0, 5 and 7.5% whey in the 21th day was 7.37 ± 0.17, 7.87 ± 0.17, and 7.48 ± 0.17 log cfu/ml, respectively. The results of sensory evaluation showed that in the samples of kefir drinks containing 5 and 7.5% whey produced the highest score in overall utility. According to the results, it seems that kefir dough containing 7.5% whey can be used to produce kefir drink.