The Biuret Complex of Gelatin and the Mechanism of Gelation

THE gelation of gelatin results from a thermally reversible cross-linking process involving hitherto unknown functional groups. In studies of gelation–molecular weight correlations of chemically modified gelatins (amino-acetylated, carboxyl-esterified, hydroxyl-acetylated, guanidino-nitrated) and of hypo-bromite-treated gelatin we have found that the polar and charged side-chain groups are of little importance in gelation1. Further, by study of the effects of various electrolytes on the melting points of gels of gelatin and of chemically modified gelatins, we have found that binding of ions at the polar and charged side-chain groups is not the mechanism by which electrolytes affect gelation2. These results have directed our attention to the role of the peptide group.