Biochemical characterisation and functional properties of pigmented rice (Oryza sativa L.) genotypes and their flakes with emphasis on starch fractions, dietary fibre and antioxidant activity

Abstract

The present study was undertaken to investigate the biochemical characteristics and functional properties of selected pigmented rice varieties and their flaked products, with particular focus on starch composition, dietary fibre content and antioxidant activity. Five pigmented rice varieties, namely MSN 100, MSN 104, MSN 20-13, KMP 220 and JYOTHI, were evaluated in both grain and flaked forms to assess the effect of flake processing on their nutritional and functional quality. The total starch content in the rice grains ranged from 69.30–70.46 %, with a slight reduction observed after the flaking process. All the varieties belonged to the intermediate amylose group (20–25 %), indicating moderate cooking and processing suitability. The amylose to amylopectin ratio showed no significant change after flake processing. The total dietary fibre content varied significantly among the varieties, ranging from 5.53–7.12 g/100 g, with KMP 220 recording the highest value. Flake processing resulted in a slight reduction in soluble dietary fibre, while a moderate increase was observed in insoluble dietary fibre and total dietary fibre content. Antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and fluorescence recovery after photobleaching (FRAP) assays, which revealed significant variation among the rice varieties. JYOTHI and KMP 220 consistently exhibited higher antioxidant activity compared to the other varieties. Although flaking caused a slight reduction in antioxidant activity, the relative ranking of the varieties remained unchanged. Overall, pigmented rice flakes retained substantial nutritional and functional properties, supporting their potential as value-added and health-promoting cereal products.