Studies on the Proteolytic Action of Dairy Lactic Acid Bacteria

Part III. Changes of the Casein Treated with Streptococcus cremoris

Abstract

Strefitococcus cremoris was cultivated for 7 days at 30°C in sterilized skim milk or in the sterilized 10% solution of dry skim milk. This skim milk culture was divided into precipitate and supernatant by centrifugation. The absorbancy at 280mμ of the supernatant prepared from the skim milk culture of S. cremoris was higher than that of the control supernatant.
Casein prepared from the skim milk culture of S. cremoris was less hydrolyzed by rennet than control casein at pH 7.0.
According to the free boundary electrophoretic analysis of the treated casein in M/10 veronal buffer of pH 8.5 containing urea, a-casein seemed to be hydrolyzed by S. cremoris but β-casein did with more difficulty.