Oil production by fermentation of lactose and the effect of temperature on the fatty acid composition1

Strains of the yeasts Candida curvata and Trichosporon cutaneum were isolated that were able to ferment the lactose of cheese whey and ultrafiltered whey permeate to produce oil. Rapid fermentation rates and lactose utilization were achieved by the G curvata strains. The fermentation was more efficient on permeate than whey, because the organisms used whey protein very poorly. Methods of extracting the oil were compared, and the best results were obtained by sequential extraction with methanol and benzene or by ethanol and hexane. The fatty acid composition of the yeasts varied with the growth temperature, fermentation time, and medium. The oil was rich in 18:1, 16:0, and 18:0. The process is a technically feasible means of using whey permeate.