Changes in molecular size and chemical properties of gelatin caused by the reaction with oxidizing methyl linoleate.

Abstract

Gelatin, soy protein, lysozyme, succinyl-casein and succinyl-egg albumin were allowed to react with methyl linoleate (ML) at a relative humidity (RH) of 0% at 50°C for 7 days (protein: ML = 1:1). Gel filtration indicated that only gelatin was extensively fragmented. The gelatin was then incubated with ML under various conditions, and changes in the molecular sizes, the gel forming abilities and the chemical characteristics were investigated. The fragmentation of gelatin was increased by decreasing the RH and with the increase in the ratio of ML to protein. The melting point of gel in heating and cooling gelatin was decreased by increasing the fragmentation. The contents of amide and carbonyl groups increased and that of amino group decreased as the reaction progressed at RH 0%, but no change in C-terminal amino acids was observed. Following the reaction at RH 0%, many kinds of amino acid residues of gelatin were damaged, although in our previous paper [Matoba et al.,Agric. Biol. Chem. , 46, 979 (1982)] su...