On Substances which affect Milk Coagulation by Lab-ferment. VI

Determination of calcium content in the casein coagulated by rennet or pepsin indicated that the amount of calcium bonded increases in proportion to pH when the application of the two enzymes to milk is made within the range of isoelectric point of casein to pH 7.0, with smaller content in milk serum. In the milk of same pH, coagulation time changes with the strength of enzyme activity but the content of calcium in coagulated casein remains constant. Calcium in coagulated casein dissolves out reversibly by acidification and there is no great variation of pH in the course of milk coagulation by the two enzymes. Ultraviolet absorption spectra of coagulated casein by the two enzymes and that of natural casein were measured. There was no difference among the three at pH 2.0 but at pH 11.0, the absorption band of the coagulated casein at around 276-290mμ was different from that of natural casein.