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 degrees, 17.1 degrees, 18.2 degrees and 23.0 degrees. Pasting properties and transition temperatures were decreased after polishing treatment. Polishing resulted in changes in the crystallinity, enthalpy and morphology of rice flours.