Functional properties, antioxidant activity and in-vitro digestibility characteristics of brown and polished rice flours of Indian temperate region

The present investigation was aimed to study functional properties, antioxidant activity and in-vitro digestibility characteristics of brown and polished flours obtained from four rice cultivars (SR-4, K-39, Mushq Budij and Zhag) of Kashmir. Brown rice flours had higher total dietary fibre (3.08%–3.68%), oil absorption (116.0%–139.0%), emulsion capacity (4.78%–9.52%), emulsion stability (87.46%–99.93%) and resistant starch content (6.80%–9.00%) than polished flours. However, polished flours presented greater water absorption (102.0%–122.0%), foaming capacity (8.00%–13.63%), apparent amylose (19.16%–22.62%), peak (2260.0–2408.0 cP), trough (1372.0–1589.0 cP) and breakdown (714.0–978.0 cP) viscosities than their brown counterparts. Brown rice flours depicted highest total phenolic content (4.40–6.40 mg GAE/g) and inhibition of lipid peroxidation (19.50%–33.20%). However, equilibrium starch hydrolysis percentage (C_∞) and predicted glycemic index of brown rice flours were lower than their polished counterparts. Among rice cultivars, brown Zhag flour had the highest total dietary fibre (3.68%), emulsion capacity (9.52%), emulsion stability (99.93%), resistant starch (9.00%), DPPH radical scavenging activity (85.45%) and inhibition of lipid peroxidation (33.20%), respectively. Emulsion capacity and emulsion stability were positively correlated with protein content of rice flours. However, peak, trough, breakdown and setback viscosities were negatively correlated with protein and fat contents of rice flour. The present investigation will be helpful in identifying nutritive role of rice flours from studied cultivars in human diet.