PROTEIN CONTENT AND COMPOSITION OF WAXY RICE GRAINS

Abstract

Rice is not only an important cereal as a major food worldwide but also valuable sources of nutritional and nutraceutical substances for human health. Protein is one of the major factors determining eating, processing and nutritional qualities of rice. Therefore, we examined effect of cultivar on the content and composition of proteins in waxy rice grains. Grains of eight waxy and one non-waxy Korean rice cultivars used in this study were produced at the N fertilizer level of 7 kg/10a. Crude protein content was higher in waxy cultivars than in the non-waxy cultivar. There was a considerable variation in crude protein contents among waxy cultivars, ranging from 8.6 to 9.7% in brown rice and from 8.1 to 8.5% in milled rice. There was also a significant varietal variation in content of the four protein fractions. The mean contents of albumin, globulin, prolamin, and glutelin fractions of waxy brown rice were 1.86, 0.50, 0.05, and 7.31%, respectively. Those of milled rice were 0.50, 0.30, 0.1, and 8.40%, respectively. Albumin, globulin, prolamin, and glutelin fractions for brown and milled rice were composed of seven, five, one, and five major bands, respectively, and no cultivar- or tissuespecific variations were apparent in the fractional profiles detected on sodium dodecy sulfate-polyacrylamide gels. Thus, the varietal differences of total and fractional proteins were mostly contributed by quantitative rather than qualitative variations.