Hydration, swelling and solubility behaviour of rice in relation to other physicochemical properties

Water uptake at 90°C and above in 16 rice cultivars, representing eight cooking‐quality types, showed positive correlation ( P ≤0.001) with the surface area of the grain, while at 60°C it was negatively related to amylose ( P ≤0.01), and gelatinisation temperature ( P ≤0.001), and positively to equilibrium moisture content on soaking ( P ≤0.001). The swelling and solubility curves for all varieties showed a two‐stage swelling pattern. Swelling at 60°C was positively correlated ( P ≤0.001) with water uptake at 60 and 70°C, while swelling at 70°C, and solubility at 60 and 70°C, showed highly negative correlation ( P ≤0.001 and P ≤0.01, respectively) with water uptake at high temperatures. Waxy rices showed distinct differences from non‐waxy rices in their hydration, swelling and solubility behaviour. They swelled more but solubilised less than the non‐waxy rices at 96°C.