A review: Yeasts in kefir and kumiss

Microbiological differences between kefir grain, kefir beverage made from cow's milk and kefir grain as well as industrially produced kefir beverage are reported. An important aspect with this fermentation product is the symbiosis between yeasts and bacteria. Different maturities cause changing population compositions. Blowing of packages or bottles is a marketing risk. Product failures by insufficient population control are often. The absence of yeasts or the predominance of yeasts lacking lactose-fermentation result in a weakly sparkling kefir product with low ethanol concentration, while a too high yeast number leads to the product deficiency "yeasty". Kumiss contains as a rule the lactose-fermenting yeast species Kluyveromyces marxianus and K. lactis, some galactose-fermenting yeast species as well as mostly different yeast species with pellicle producing tendency.