Cereal Chem 57:133 - 137.  |  VIEW ARTICLE
Methods of Separation of the Major Histological Components of Rice and Characterization of Their Proteins by Amino Acid Analysis.

J. H. Bradbury, J. G. Collins, and N. A. Pyliotis. Copyright 1980 by the American Association of Cereal Chemists, Inc. 

Two methods, developed for the clean separation from rice of aleurone with attached grain coats, involved soaking de-embryonated grains in water or in formic acid plus sucrose and then scraping off the starchy endosperm. The aleurone cell fine structure was retained in the water treatment but destroyed in the formic acid treatment, which also ruptured aleurone cell walls. Grain coat walls were obtained by ultrasonication of rice grains in decane. Analyses of these components as well as of embryo, starchy endosperm, and the whole grain allowed a satisfactory quantitative balance to be made of the amino acid and protein content of the grain and its major histological components. The embryo, aleurone cells, and grain coat together amount to about 9% of the grain by weight, yet they contain 17% of the protein and 23% of the lysine. Because these histological components (which also contain the bulk of the vitamins in rice) are removed as bran during milling, the promotion of increased consumption of brown rice rather than of milled rice seems desirable even though protein from brown rice is less digestible than that from milled rice.