Abstract
SUMMARY Formation of covalent bonds at milk sterilization temperatures was studied using caseins and casein peptides. At 120°C lysinoalanyl residues produced even at pH 7·0 were derived from intra-molecular interactions between phospho-serine and lysine; the conditions of formation were determined. It was also found that the formation of isopeptidic cross-links was significant with conditions more severe than those used for milk sterilization.