Cheese casein was isolated from various aged Gouda and Cheddar cheese and their calcium binding ability was determined at pH 6.0. The amount of bound calcium increased with the concentration of calcium ion until 15mM. At a given concentration of calcium, the cheese casein obtained from a younger cheese bound more calcium than that from an older cheese. The quantity of bound calcium decreased with the age of cheese became older but most decrease was observed in the early stage of the ripening.

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... milarly, both the degradation of cheese protein and the decrease of phosphorous content of cheese casein occured remarkably in the respective stage of the ripening. From the existence of a very closed corelation between the amount of bound calcium and the phosphorous content, it is deducible that calcium was bound to a residual phosphate ester in the cheese casein. During ripening of cheese, as-casein was more degraded than the other components of the cheese casein and became to lower molecules containing lower amount of phosphorous. Consequently, it can be considered that the variation of bound calcium to protein of cheese during ripening was affected by the degree of degradation and the phosphorous content of as-casein.