Texture and Fine Structure of Cooked Brown Rice

Abstract

The texture and structure of brown rice were compared to under-milled and well-milled rice to determine the most suitable method for cooking brown rice. The absorbance of brown rice at 20°C and 30°C was slower than that of milled rice, but reached a similar level after a 2-hour soaking at 60°C. The water content and grain size of brown rice were both smaller than milled rice when cooked. Cryo-scanning electron microscopy showed that the peel, seed coat and aleurone layer of brown rice were progressively removed as the degree of polishing increased. The amyloplasts in starch cells swelled more in milled rice than in brown rice when the rice was soaked in water.The small pores (water trace) in cooked rice increased with increasing degree of polishing, suggesting that the gelatinization of starch was sufficient. However, brown rice was rated worse than milled rice by a sensory evaluation.