PHASE-EQUILIBRIA AND GELATION IN GELATIN MALTODEXTRIN SYSTEMS .4. COMPOSITION-DEPENDENCE OF MIXED-GEL MODULI

The storage moduli (G') of phase-separated co-gels formed by quench-co oling mixed solutions of gelatin and potato maltodextrin (Paselli SA-2 and SA-6) have been related quantitatively to the experimentally-dete rmined concentration-dependence of G' for the constituent polymers. Di stribution of water between the phases was examined explicitly by usin g polymer blending laws to derive calculated moduli for gelatin-contin uous and maltodextrin-continuous networks over the entire range of sol vent partition. Allowance was made for the direct contribution of poly mer chains, and for density differences between the phases, in calcula ting relative phase-volumes. The effect of gel formation prior to phas e-separation was calculated using classical theory for network de-swel ling. Good agreement with observed moduli for more than 30 gelatin/mal todextrin combinations was achieved using a single adjustable paramete r, p (the ratio of solvent to polymer in the gelatin phase divided by the same ratio for the maltodextrin phase), with an optimum value of p approximately 1.8 for both SA-6 and SA-2.