Physico-chemical, morphological, thermal, cooking and textural properties of chalky and translucent rice kernels

Studies were undertaken to compare physico-chemical, morphological, thermal, cooking and textural properties of chalky and translucent kernels separated from three rice cultivars. Physico-chemical properties, such as 1000 kernel weight, bulk density, kernel hardness, length-breath (L/B) ratio and amylose content, were determined. The morphological properties of chalky and translucent kernels were studied using scanning electron microscopy while the thermal properties were determined by differential scanning calorimetery. The chalky kernels separated from different cultivars showed higher 1000 kernel weight and bulk density but lower kernel hardness and amylose content than their counterpart translucent kernels. Microscopic analysis revealed that the cells, as well as amyloplast, were loosely packed in the chalky kernels. Chalky grains showed higher transition temperatures, enthalpy of gelatinization, peak height index and gelatinization range than the translucent grains. The cooking and textural properties of chalky and translucent kernels differed significantly. The chalky kernels from different varieties showed lower values for cooking (cooking time, water uptake, L/B ratio and elongation ratio) and textural parameters (packability, cohesiveness, chewiness, hardness) than the translucent kernels.