Effects of Polishing on Proximate Composition, Physico- Chemical Characteristics, Mineral Composition and Antioxidant Properties of Pigmented Rice

The effects of polishing on proximate compositions, physico-chemical characteristics, mineral compositions and antioxidant properties of the rice flours obtained from three different pigmented rice varieties (Chak-hao Angangba, Chak-hao Amubi and Chak-hao Poireiton) were investigated. The rice varieties were significantly (P < 0.05) different in the contents of the test characteristics. Lipids, ash, minerals, phytochemicals (phenolic acids and flavonoids) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity of rice flours were decreased after polishing (9% degree of milling), while amylose content and lightness were increased. X-ray diffraction pattern of rice flours exhibited A-type crystalline pattern with reflections at 15.1°, 17.1°, 18.2° and 23.0°. Pasting properties and transition temperatures were decreased after polishing treatment. Polishing resulted in changes in the crystallinity, enthalpy and morphology of rice flours.