Antioxidant capacity and total phenolics content of direct‐expanded chickpea–sorghum snacks

Abstract

This study examined the effect of extrusion conditions on the antioxidant capacity (DPPH and ABTS) and total phenolics content of direct-expanded chickpea–sorghum snacks. The effect of extraction solvent on the antioxidant capacity (DPPH) detected also was determined. Chickpea–sorghum blends (50:50, 60:40, and 70:30, chickpea:sorghum, w/w) were extruded at 10 combinations of moisture content (16, 18, and 20%) and barrel temperature (120, 140, and 160°C) and at 169°C and 15% moisture, maximum extrudate expansion conditions. DPPH radical inhibition percentages of acetone–water and ethanol–water extracts were higher (p < .05) than those of hexane extracts. Total phenolics contents ranged from 1 to 7 mg gallic acid equivalents/g. Extrusion, higher barrel temperature, and a larger proportion of sorghum in the blend increased (p < .05) DPPH radical inhibition, Trolox equivalents, and total phenolics content, whereas higher moisture content decreased (p < .05) these values. The 50:50 chickpea:sorghum blend extruded at 160°C and 16% exhibited the highest antioxidant capacity and total phenolics. Practical applications Extruded snacks are susceptible to oxidation due to their porous structure. Chickpea–sorghum expanded snacks are even more subject to oxidation as chickpea has a relatively high-fat content. This study demonstrated that a higher level of sorghum in chickpea–sorghum snacks increased antioxidant capacity and total phenolics content, implying sorghum can play a major role in increasing the oxidative stability of the snacks. Extrusion parameters such as barrel temperature and feed moisture content also impacted the antioxidant capacity and total phenolics content of the snacks. Acetone–water and ethanol–water were superior to hexane for extracting antioxidants.