| Abstract: | Although the effects of water and sugars upon starch gelatinization have been studied at a physicochemical level, little work has been performed on the time dependence of the component processes of gelatinization. It has been shown using a temperature jump technique and monitoring changes by small angle light scattering that the rate of loss of birefringence of 23% w/w wheat starch suspensions in water depends on the size of the temperature jump. Two processes, one fast and one slow are present, the fast predominating in temperature jumps of 8°C, while slower changes are evident in jumps of 2–4°C. The behaviour of wheat starches reflects their different pretreatments. The results have been interpreted in terms of there being a mutual interdependence between the energy relationships governing the stability of the crystallites and the conformation of the chains in the amorphous regions. A semi-cooperative view of the gelatinization process is proposed. |
