PHYSICOCHEMICAL PROPERTIES OF LOW-AMYLOSE RICE

Low-amylose rice will be supposed to increase in quantity as food mate rials. So, physicochemical properties of milled rices were investigate d in consideration of amylose content using 19 varieties of non-glutin ous rice, 11 of low-amylose rice and 10 of glutinous rice. The amounts of acid hydrolysis residue from rice starches showed high correlation with amylose content (r = 0.917*). The amount of the residue of glut inous rice starches, low-amylose rice starches and non-glutinous rice starches was 30-81, 183-252 and 305-516 mg/100 g, respectively. Water absorption of milled rices showed high correlation with either amylose content (r = -0.955*) or the water absorption of rice starches (r = 0.953*). The water absorption of rice starches from glutinous rice, l ow-amylose rice and non-glutinous rice was 49.3-50.8, 47.0-48.3 and 44 .5-47.8%, respectively. From this result, water absorption of milled r ices would depend on that of rice starches. Peak viscosity of amylogra ph characteristics showed high correlation with amylose content (r = - 0.923*). Tan delta (= G''/G') of cooked rice showed high correlation with amylose content (r = -0.944*), and the tans of glutinous rice, l ow-amylose rice and non-glutinous rice was 0.426-0.529, 0.360-0.415 an d 0.196-0.349, respectively. Acid-solubility showed high correlation w ith either amylose content (r = -0.973*) or tan delta of cooked rice (r = 0.951*). The acid-solubility of glutinous rice, low-amylose rice and non-glutinous rice was 92.2-99.4, 79.6-84.3 and 52.5-77.5%, respe ctively. However, these components showed no correlation to protein co ntent of milled rices. From these results, it was concluded that low-a mylose rice whose amylose content was less than 14.0% were intermediat e properties between glutinous rice and non-glutinous rice for all the components related to amylose content.