Modelling of brown rice and limited-water cooking modes and its potential use for texture prediction

This paper describes the adaptation of a one-dimensional rice cooking model including water transfer, starch phase transitions and swelling to simulate both milled and brown Chu-cheong and Chil-bo rice cultivars cooked in excess water or in limited amounts of water. The pericarp was found to play a temperature- dependent role during steeping of brown rice. At 50 _C, surface mass-transfer resistance was identified whereas from 75 _C the pericarp ruptured. Despite pericarp rupturing, apparent water diffusion coefficients for brown rice (_1.9 _ 10_10 m2 s_1) were lower than for milled rice (_3.3 _ 10_10 m2 s_1). This was due to the mechanical constraining effect of pericarp with respect to water uptake. In the limited- water cooking mode, predicted water and gelatinization profiles of four selected cooking procedures explained the texture of cooked rice. Indeed, the highly hydrated gelatinized periphery of the cooked grain resulted in high ''initial starchy coating'' sensory scores whereas the uncooked core increased instrumental firmness. (Résumé d'auteur