Modelling of water transport and swelling associated with starch gelatinization during rice cooking

An isothermal model of rice cooking process was developed that accounts for the impact of starch phase transition on water transfer and swelling, using an arbitrary Lagrangian-Eulerian framework. Two water populations were distinguished: water in native starch and excess water absorbed by starch since it starts to gelatinize. The model was solved by FEM. Water apparent diffusivities in native and gelatinized starch were 3.6 × 10−10 and 2.8 × 10−10 m2 s−1 respectively. The model was validated on the Chil-Bo rice cultivar using experimental water uptake and microscopy measurements of the gelatinization front. At 50 °C, 75 °C and 95 °C, the volume gains were 0.3, 4.8 and 8.3 m3 m−3 respectively. The model adequately reproduces swelling as its extent corresponds to the amount of water absorbed (±4% v/v). Both water and gelatinization profiles over time would be of tremendous benefit for the optimization of cooked rice properties such as texture.