Design of gluten-free instant whole acorn-maize blended flour by extrusion process

Gluten-free products have become popular due to the increasing number of people with gluten-related disorders. In this study, the effect of whole acorn flour and whole maize flour levels of 25, 62.5, and 100% and extrusion process variables, including screw speed 120, 160, and 200 rpm and feed moisture content of 12, 15, and 18%, on the production of gluten-free products were investigated. The results demonstrated that increasing the whole acorn flour had a positive effect on water absorption index, angle of repose, carr index, and Haussner ratio, but negatively impacted expansion index and water solubility index. Increasing feed moisture had a notable impact on increasing bulk density and hardness and bowl life hardness while decreasing water solubility index. The optimal conditions for the fabrication of the blended meal were whole acorn flour 63.81%, 120 rpm screw speed, and 18% feed moisture content. The samples produced in these conditions had an 18.23 expansion index, 6.34 humidity, 4.93 g g(-1) water absorption index, 0.16 g g(-1) water solubility index, 5.70 N hardness, 2.85 N bowl-life, L * 60.29, 26.14 angle of repose, 1.15 Haussner ratio, and 14.31 carr index. Our findings suggest an innovative approach for applying whole acorn flour to prepare nutritious gluten-free instant products by extrusion processing.