New Trends in Kefir Yeast Technology

Abstract

The development of new biotechnologies and foodstuffs using kefir yeast are reviewed. The strategy adopted was to examine fermentations of synthetic media containing sugars of raw materials and wastes of food production. Kefir cell growth was also examined. An important efficiency of kefir yeast in glucose, fructose, sucrose and lactose fermentations have been proven. Fermentations were performed in comparison with immobilized biocatalysts prepared by immobilization of kefir on delignified cellulosic (DC) materials, gluten and mineral kissiris. DC material supported kefir is suitable for low-temperature alcoholic fermentation in the range of 5–15°C.

The above research supported the development of technologies and products using whey. Therefore, the production of an alcoholic drink, potable and fuel-grade alcohol and SCP production from whey are reported. Whey fermentation by free cells resulted in a fermentation time of 35h, while DC material supported cells of kefir gave less than 10h. The addition of 1% raisin extracts reduced the fermentation time in whey fermentation by free cells to 12h. Mixtures of whey with molasses were also used to increase alcohol concentration. The SCP production using whey resulted to granular biomass lead to avoidance of centrifugal separators in production plants. Kefir protein showed improved emulsifying, foaming and gel forming properties in comparison with Soya protein and fermented wort at 15°C. in one day for brewing. That research was the basis for scale-up processes in a pilot plant with 100L, 1000L, 10,000L bioreactors for repeated batch and continuous processes employing kefir granules and DC materials supported kefir.