THE MECHANISM OF THE CROSS-LINKING REACTION OF GELATIN WITH HARDENER

The reaction, in solution, between gelatin and various hardeners has been examined by gel permeation chromatography, HPLC and amino acid analysis. It is concluded that there are two types of crosslinking reaction. One of them is the reaction between the hardener and the lysine and hydroxylysine residues in gelatin, whilst the other is the reaction between the hardener and the amino acid residues, except lysine and hydroxylysine. The crosslinking reactions are influenced by the reaction conditions including pH value, concentration etc. The amount of unreacted lysine, determined by amino acid analysis, correlates with the reduction in the level of a-component due to the crosslinking reaction. It is considered that the results suggest that interchain crosslinking reactions, at the lysine and hydroxylysine residues, mainly take place in gelatin solution.