Effect of sugars on the gelatinisation and rheological properties of sago starch

The effect of various sugars on the gelatinisation and rheological properties of sage starch have been studied using differential scanning calorimetry and small deformation oscillation techniques. Sugars were found to increase the gelatinisation temperature, T-p and gelatinisation enthalpy, DeltaH in the following order: control (water alone) < ribose < fructose < glucose < maltose < sucrose. The effect of sugars on T-p and <Delta>H has been attributed to the reduced plasticizing effect of the sugars compared to water, to sugar-starch interaction and to the effect of sugars on the water structure. The swelling and amylose leaching were reduced in the presence of sugars. Due to the low amylose content in the gelatinised starch samples, the storage modulus, G' was reduced significantly in the presence of sugars. Generally G' decreased in the following order : control (water alone) > hexose > disaccharides > pentoses.