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Abating whey organic load through ethanol and lactic acid production by kefir

Soupioni, Magdalini, Vlachou, Kyriaki, Psarologou, Alexandra, Bekatorou, Argyro
Toxicological and environmental chemistry 2016 v.98 no.10 pp. 1191-1199
alcoholic fermentation, biochemical oxygen demand, carbon, cellulosic materials, chemical oxygen demand, ethanol, grapes, immobilized cells, isotope labeling, kefir, lactic acid, lactic fermentation, lactose, pH, radionuclides, spent grains, whey
The extent to which selected ethanol and lactic acid production bioprocesses contribute to whey waste abatement was examined. Alcoholic fermentation of whey was carried out by kefir cells immobilized on grape stalks, delignified cellulosic materials, or brewer's spent grains. Lactic acid fermentation was also performed by free kefir cells with or without addition of brewer's spent grains as promoting material. Since whey fermentation rate is affected by the lactose uptake rate, ¹⁴C-labeled lactose was used to study the fermentation ability of kefir. The highest reductions in biochemical oxygen demand and chemical oxygen demand of whey, about 68% and 52%, respectively, were achieved by lactic acid fermentation in 6 h at 37 °C and pH 5.5, in the presence of 120 g brewer's spent grains. Additionally, at the same conditions, the highest ¹⁴C-labeled lactose uptake rate by kefir and consequently the highest alcoholic fermentation rate were also recorded. However, greater reductions in biochemical oxygen demand and chemical oxygen demand of whey are required prior to final disposal.