Effects of extrusion processing on the bioactive constituents, in vitro digestibility, amino acid composition, and antioxidant potential of novel gluten-free extruded snacks fortified with cowpea and whey protein concentrate

This study aimed to develop novel gluten-free snacks from rice flour, cowpea and whey protein concentrate (WPC) enriched with bioactive and antioxidant properties. The effects of extrusion on bioactive compounds (sucrose-galactosyl oligosaccharides, insoluble dietary fibre, resistant starch, phytic acid, trypsin inhibitory activity), protein digestibility, amino acid composition, total phenolic content and antioxidant properties were evaluated by comparing raw formulations and extruded snacks. Rice flour (100%) was used as a control. Extrusion increased the oligosaccharides (2–3 fold) and resistant starch (1–3 fold), whereas the insoluble fibre content was not significantly affected. Extrusion increased in vitro protein digestibility (p < 0.05) and amino acid composition in snacks. Extruded and raw samples enriched with cowpea and WPC had an increase in total phenolic content (TPC) and antioxidant activity. Extrusion significantly reduced the TPC and antioxidant properties of extruded snacks compared to their raw counterparts. The results obtained in this study respond to the growing interest of the food industry to cater to consumer demand for healthy novel gluten-free expanded snacks with bioactive compounds.