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

•Cowpea and whey protein concentrates enhance protein digestibility.•Extrusion manipulates the carbohydrate and protein complexes.•Antioxidant activity is related to protein composition.•Cowpea inclusion resulted in oligosaccharide enhancement. 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