Comparison of ethanol production from cheese whey permeate by two yeast strains.

The objective of the present laboratory scale experiment was to compare ethanol production by Kluyveromyces marxianus strain ATCC8554 and Candida kefyr ATCC 14245 from unconcentrated and concentrated cheese whey permeate. The results indicated that ethanol production was greater when using concentrated whey permeate (9.8% lactose) compared to unconcentrated whey permeate (4.9% lactose) by both the yeasts, especially in presence of growth supplements. The rate and extent of ethanol formation increased noticeably and partly linearly for both the yeasts with sharp and partly linear decrease in both lactose and Chemical Oxygen Demand (COD), especially after the first 10 h of fermentation; total time of fermentation was 60 h. The optimum pH and temperature conditions for ethanol production were 4.8 and 30º C respectively. Klu. marxianus strain had greater ethanol producing ability from cheese permeate whey than Can. kefyr.