Volatile Fatty Acids Produced by Some Lactic Acid Bacteria. I. Factors Influencing Production of Volatile Fatty Acids from Casein Hydrolysate

Abstract

The effect of several conditions of substrate on total and individual volatile fatty acids (VFA) produced from casein hydrolysate by resting cells of three strains of lactic streptococci and two strains of lactobacilli has been studied. Fatty acids were steam-distilled from the reaction mixture and total and individual VFA determined by titration with alkali and by gas chromatography. Optimum pH of substrate was in the neutral or slightly alkaline range. Optimum temperature of incubation was 32 C for streptococci and 42 C for lactobacilli. Shaking incubation was more favorable to production of VFA than static incubation. There was no appreciable difference in total VFA production between incubations with air and with nitrogen atmosphere. Addition of sodium caseinate to casein hydrolysate stimulated VFA production, whereas addition of lactose or milk fat showed a slight inhibitory effect. Patterns of individual VFA varied from strain to strain, depending on the conditions of substrate. © 1965, American Dairy Science Association. All rights reserved.