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

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Abstract
The effect of several conditions of substrate on total and individual volatile fatty-acids (VFA) produced from casein hydroly-sate by resting cells of 3 strains of lactic streptococci and 2 strains of lactobacilli were 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[degree]C for streptococci and 42C for lactobacilli. Shaking rather than static incubation was more favorable to production of VFA. There was no appreciable difference in total VFA production between incubations with air and N atmosphere. Addition of sodium-caseinate to casein hydrolysate stimulated VFA production, whereas addition of lactose or milk fat was slightly inhibitory. Patterns of individual VFA varied from strain to strain, depending on the conditions of substrate.