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In vitro Digestibility of Whey Protein/ K ‐Casein Complexes Isolated from Heated Concentrated Milk
Author(s) -
SINGH HARJINDER,
CREAMER LAWRENCE K.
Publication year - 1993
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1993.tb04260.x
Subject(s) - casein , chemistry , whey protein , hydrolysis , chromatography , pepsin , trypsin , centrifugation , chymotrypsin , beta lactoglobulin , proteolysis , polyacrylamide gel electrophoresis , enzyme , biochemistry , food science
The disulfide‐linked complex of K ‐casein and whey proteins that forms when concentrated milk is heated was isolated by centrifugation and column chromatography on Sephacryl S‐1000. The rate of hydrolysis of β‐lactoglobulin and K ‐casein in the complex and the reduced and carboxymethylated components of the complex were measured by polyacrylamide gel electrophoresis. The rates of hydrolysis at pH 2.0 (pepsin) and pH 8.0 (trypsin and chymotrypsin) were similar for k ‐casein in the complex and its reduced form. β‐Lactoglobulin hydrolysis was faster for the reduced complex than for the complex which was much faster than for the native protein for all three enzymes. The results suggest that heating milk increases the digestibility of whey proteins, despite the formation of large protein complexes between the whey proteins and K ‐casein.