Physicochemical characterisation of corn extrudates prepared with varying levels of beetroot (Beta vulgaris) at different extrusion temperatures

Abstract

SummaryThis study examines the effect of beetroot powder (BRP) incorporation (0%, 5%, 10% and 15%) at different extrusion temperatures (125, 150 and 175 °C) on the physicochemical, antioxidant and sensory properties of corn grit (CG) extrudates. BRP showed higher values of total phenolic content (TPC = 9095 μg GAE g−1) and free radical inhibition (ABTS = 6.5 μm trolox mg−1 and DPPH = 7.9 μm trolox mg−1) than CG (1346 μg GAE g−1, 1.5 μm trolox mg−1 and 2.2 μm trolox mg−1, respectively). Pasting viscosity (peak, breakdown and final) decreased, while pasting temperature of CG increased with the level of BRP incorporation. Analyses of the extrudates showed an increase in redness, bulk density, hardness, TPC, free radical inhibition, total dietary fibre (TDF) and a decrease in water absorption index (WAI), water solubility index (WSI), expansion ratio and oil uptake with the increase in the level of BRP incorporation. On the other hand, higher extrusion temperature increased porosity, WAI, WSI, oil uptake but decreased redness, bulk density, hardness and TPC.