Chemical changes in casein heated with and without d-glucose in the powdered state or in an aqueous solution
Abstract Chemical changes in casein, heated either in the presence or the absence of d -glucose at 50 or 75°C in a powdered state at 75% relative humidity (RH), or in an aqueous solution, were investigated. During heating, colour development, the formation of polymerised products and severe decomposition of amino acid residues occurred. In the powder reaction system, mainly basic amino acids decomposed whereas, in the solution system, all amino acids were uniformly decomposed. In addition, small amounts of free amino acids and low molecular weight peptides (below MW 500) were detected, these amounts being greater in the solution system, suggesting that non-enzymic cleavage of peptide linkage occurred. These changes were observed both in the absence and in the presence of glucose but glucose promoted such changes.