Starch gelatinization in the surface layer of rice grains is crucial in reducing the stickiness of parboiled rice

Abstract

Parboiled rice has high nutritional value but unpleasant palatability. In this study, rice stickiness was significantly reduced by steaming during the parboiling process; however, continuing steaming past certain durations no longer affected rice stickiness. It was also found: (i) the degree of starch gelatinization (DSG) increases and starch crystallinity decreases with increasing steaming time; (ii) the molecular size and chain length distribution (CLD) of leached starch for both white and parboiled rice are significantly different from those of native starch; (iii) the relation between leached amylopectin amount and rice stickiness explains the reduced stickiness by parboiling; and (iv) starch gelatinization in the surface layer of rice grains during parboiling might be critically important in blocking starch leaching, consequently leading to a less sticky texture. This study supplies a way to manage glutinous rice stickiness by parboiling for the production of non-sticky rice foods.