Application of whey in fermented beverage production using kefir starter culture

Purpose - Milk whey is a by-product of the cheese-making industry which presents about 85-95 per cent of the milk volume. Whey fermentation by the isolated kefir starter culture could be a sensible solution for the use of this by-product from the dairy industry. For the first time, in Iran the microbial flora of kefir grain was isolated and identified (Motaghi et al.). This paper aims to examine the various ratios of starter culture of kefir grain for production of fermented beverage using whey as the substrate. Design/methodology/approach - Various ratios of lactic bacteria, yeasts and acetic acid bacteria were tested. The incubation time (24 h) temperature (25 degrees C), substrate (pasteurized whey), and inoculation rate (3-5 per cent) and mixing rate (90 rpm) were the same for the all products. The products were analyzed for protein, fat, sugar, alcohol, carbon dioxide, acidity, density, dry material, ash, and riboflavin content. Findings - The quality (smell and flavor) of the product was assessed. Samples produced with 3 per cent (v/v) lactic acid, acetic acid bacterial mixed cultures and 2 per cent (v/v) yeast culture were considered as best with respect to quality and organoleptic quality. Originality/value - The ability of kefir starter cultures to ferment whey to formulate and mix cultures consisting of certain species of kefir grain micro-organisms in-order to develop a procedure where lactic acid fermentation is followed by yeast fermentation. The potential of local kefir starter culture in production of healthy beverage from whey is a new finding since this particular beverage has the taste of artificial butter milk and it is naturally carbonated.