Rice starch and Co-proteins improve the rheological properties of zein dough

While increasing cases related to gluten intolerance have encouraged scientists to develop healthier and better-quality gluten-free products, a more ideal viscoelastic behavior is still needed. In this study, we systematically investigated a dough system composed of corn zein, starch, and additional protein (5% of total protein, termed "co-protein") to achieve similar rheological properties of wheat dough. Three types of starches (corn, wheat, and rice) and four types of co-proteins (casein, sodium caseinate, gliadin, and glutenin) were combined with zein at room temperature and at 35 °C, above zein's glass transition temperature. In small and large deformation tests, only rice starch was found to improve significantly the functionality of zein dough, resulting in formulations with similar rheological properties to wheat dough, i.e., low phase angle value, high complex modulus, and high extensional viscosity implying an elastic dough with high strength and resistance to deformation. Rice starch also significantly lowered glass transition temperature of zein dough, associated with improved performance even at room temperature. Combining zein with a proper starch type, and in cases co-proteins, substantially improved rheological properties of zein dough similar to that of wheat dough, with potential implications to the gluten-free and the plant-based protein market.