The influence of glycerol on structural changes in waxy maize starch as studied by Fourier transform infra-red spectroscopy

The influence of glycerol on the retrogradation kinetics for waxy maize starch-water systems was monitored by Fourier transform infra-red spectroscopy. The spectra showed the CC and CO stretching region (1300-800 cm−1) to be sensitive to the retrogradation process. A multistage kinetic process in terms of structural changes on a molecular level was observed during the retrogradation of waxy maize in a 10% (w/w) gel. For the first two stages (formation of helices and induction time for helix aggregation) no significant kinetic differences were observed in the gels with various glycerol contents. Stage three is described as the primary aggregation and crystallization step. In the final stage, syneresis of water occurs. The calculated rate constants clearly show decreasing retrogradation of waxy maize starch with increasing glycerol content. The effects are explained in terms of starch-glycerol interactions and stabilization of water resulting in a decreased mobility of the starch chains.