Influence of different culturing conditions on kefir grain increase

Kefir grains are the natural starter used during kefir production. Factors influencing grain increase-incubation temperature of 18, 22, 25 or 30degreesC, enrichment with combinations of tryptose (20 g/L) and yeast extract (20 g/L), and cultivation with and without agitation-were studied to develop a method for mass grain production. The highest grain increase (582%) was found with activated grains cultivated with agitation at 25degreesC in low-fat milk containing tryptose and replacing the fermented milk daily. Full-cream milk under the same conditions gave an increase of 522%. Cultivation without agitation resulted in 175% and 173% increases for low-fat and full-cream milk, respectively.