INFLUENCE OF THERMAL HISTORY ON THE STABILITY OF GELATIN GELS

Gelatin gel properties have been studied using three techniques. Optic al rotation measurements have shown that the lower the ageing temperat ure, the faster the helix content increases but the lower the helix st ability. Rheological measurements show that a small increase in temper ature leads to a melting of some junction zones followed by a build up of new ones. By ageing the gel at two successive temperatures one can show the existence of two populations of junction zones with differen t thermal stabilities. The same result is shown on melting thermograms obtained by differential scanning calorimetry. All these results are consistent with the hypothesis of the presence of junction zones of va rious lengths, the thermostability of which being proportional to thei r lengths. (C) 1997 Elsevier Science B.V.