PROTEIN STARCH INTERACTIONS IN RICE GRAINS - INFLUENCE OF STORAGE ON ORYZENIN AND STARCH

Influence of storage on oryzenin, starch amylose, and amylopectin has been studied in grains of two U.S. rice varieties (Lemont, long grain, and Mercury, medium grain). Although total protein and starch content did not change during storage, protein solubility decreased. Storage of rice grains, especially at higher storage temperatures, resulted in increased disulfide bonds and average molecular weight of oryzenin. On the other hand, the average molecular weight of amylose decreased, but that of amylopectin increased. Oryzenin interacted with starch by reversible binding to amylopectin and/or amylose. This binding decreased during storage, especially at higher storage temperatures, and was related to the stickiness of cooked rice. © 1990, American Chemical Society. All rights reserved.