PHASE-EQUILIBRIA AND GELATION IN GELATIN MALTODEXTRIN SYSTEMS .1. GELATION OF INDIVIDUAL COMPONENTS

As a prelude to studies of co-gelation with gelatin, the gelation behaviour of Paselli maltodextrins SA-6 and SA-2 (DE almost-equal-to 6 and 2, respectively) was mapped out over the experimentally-accessible range of temperature (.7) and concentration (c), using a simple visual method to determine the time required for formation of a self-supporting network (t(g)). For both samples, log t(g) decreased linearly with log c and increased linearly with T. At equivalent temperatures and concentrations, SA-2 gelled between 20 and 60 times faster than SA-6. Selected samples were monitored more rigorously by mechanical spectroscopy, taking t(g) as the time at which elastic response (G') became greater than viscous response (G''). In all cases the values of t(g) obtained by this procedure were lower than those from visual inspection, by a constant factor of about 3.4. The concentration-dependence of gel moduli (G) for SA-2 and for gelatin (second-extract limed ossein; LO-2) fitted accurately to the form anticipated from cascade theory for normal polymer networks. For SA-6, by contrast, log G' varied linearly with log c over the entire range at which measurements could be made, indicating a different mechanism of structure-formation (such as the agglomeration of short, aggregated helices).