Thermomechanical extrusion of soybean okara as a strategy to increase soluble fiber and its application in crackers

Abstract

Soybean okara is a byproduct of the soy milk and tofu industry, containing 40% dietary fiber (dry basis), most of which is insoluble fiber. In this study, we modified soybean okara through thermomechanical extrusion and evaluate its impact on cracker formulation. Okara was processed using a co-rotating twin-screw extruder to obtain extruded okara flour (EdO). Extruded okara exhibited an increased content of soluble dietary fiber and enhanced structural porosity, resulting in greater hydration capacity and swelling power. Crackers were prepared using raw okara (non-extruded), extruded okara, and wheat bran. The cracker doughs were formulated by replacing 20% of wheat flour with okara flours or wheat bran. A sensory analysis was conducted with trained assessors, along with a consumer acceptability study. Crackers made with okara flours had greater height, crunchiness, hardness, chewability, and uniformity, with no negative impact on acceptability. In conclusion, extruded okara flour enhances the nutritional profile of crackers without compromising consumer acceptance.