Influence of lactose hydrolysis and solids concentration on alcohol production by yeast in acid whey ultrafiltrate

Abstract

Abstract Alcohol yields of 6.5% were obtained with Saccharomyces cerevisiae in lactasehydrolyzed acid whey permeate containing 30–35% total solids. Maximum alcohol yields obtained with Kluyveromyces fragilis were 4.5% in lactase‐hydrolyzed acid whey permeate at a solids concentration of 20% and 3.7% in normal permeate at a solids concentration of 10%. Saccharomyces cerevisiae efficiently converted the glucose present in lactase‐hydrolyzed whey permeates containing 5–30% total solids (2–13% glucose) to alcohol. However, the galactose, which comprised about half the available carbohydrate in lactase‐hydrolyzed whey, was not utilized by S. cerevisiae , so that even though alcohol yields were higher when this organism was used, the process was wasteful in that a substantial proportion of the substrate was not fermented. For the process to become commercially feasible, an efficient means of rapidly converting both the galactose and glucose to alcohol must be found.