EFFECTS OF HYDROXY COMPOUNDS ON GEL FORMATION OF GELATIN

Network formation of gelatin gel is known to consist of three-dimensio nally cross-linked triple helices among polypeptide chains. The effect s of added low molecular weight mono-ols, diols and polyols on the hig her-order structure formation of gelatin chains were investigated usin g the following measurements: melting temperature, viscoelasticity and spin-lattice relaxation time (T-1) of (H2O)-O-17 of gels, and circula r dichroism spectra of diluted gelatin solutions. Furthermore, hydrati on behaviors of these hydroxy compounds were evaluated from the dynami c hydration numbers (n(DHN)) derived from T-1 of (H2O)-O-17 in the sol utions. It was found that network structures of gelatin gels containin g hydoxy compounds were influenced by the number and position of hydro xyl groups as well as the number of carbon atoms of these coexisting c ompounds. The effect of hydroxyl groups of hydroxy compounds was consi dered to stabilize the helices among gelatin chains. Especially, the a ddition of polyols with large number of hydroxyl groups increased the number of cross-linking junctions in the gel networks, which consist o f the aggregation among the helices. On the contrary, the effect of ca rbon atoms of hydroxy compounds is to disturb the formation of the hel ices and the aggregation among the helices.