Reveal The Molecular Mechanism Of Starch Gelatinization By Differential Scanning Calorimetry

When heated in the presence of water, starch undergoes an irreversible order-disorder transition termed gelatinization. The granules are observed to swell, absorb water, lose birefringence and crystallinity,leach amylose. Differential scanning calorimetry (DSC) is widely used in starch gelatinization, but, a universally accepted explanation of the gelatinization process is still lacking. In this study, wheat, rice and maize were materials, we have designed a protocol using the Rapid Visco Analyser(RVA) to heat starch:water mixtures under conditions that resemble DSC heating as closely as possible. This is the frst time the RVA has been used to simulate DSC heating profles for the preparation of gelatinized starch samples to probe the molecular mechanism underlying gelatinization. Various techniques are used to gain new insights into the process of starch gelatinization. The multi-scale structure of granules and the changes that undergo during processing are the major determinants of starch functionality for food processing and human nutrition. The main results were shown as fllowings:Designed a protocol using the Rapid Visco Analyser (RVA) to heat starch:water mixtures under conditions that resemble DSC heating as closely as possible. We prepared the wheat,rice and maize starch samples as water:starch ratios (v/w) of 0.5:1,0.75:1, 1:1, 1.5:1, 2:1, 3:1 and 4:1. Each water:starch mixture was heated separately to To-10, To, Tp, Tc, Te (only wheat and maize starches), Tc+10, Tc+ 20(only wheat starch)and 95?.Changes of multi-scale structure during mimicked DSC heating reveal the nature of wheat, rice and maize starches gelatinization. The results indicated that at all water:starch ratios studied, wheat starch remained essentially constant as the RVA pre-heating below To, but both short-range order and long-range order changed significantly at Tp, some structural order was still present at the end of DSC endothermic transition(Tc) for wheat and maize starches.There was no structural order at the end of DSC endothermic transition as water: starch rations were 2:1, 3:1 and 4:1 for rice starch.Compared the multi-scale structure during mimicked DSC heating as the pre-heating temperature were Tc and Te of wheat and maize starches. The results indicated that at the same water:starch ratios, more the loss of long-range and short-range ordered structures happened as the pre-heating temperature was Te. At the water-starch ratio of 2, 3, 4, complete gelatinization of wheat and maize starches were happened with the pre-heating temperature was Te.