Thermal treatment of dry zein to improve rheological properties in gluten-free dough

Authors: FEDERICI, ENRICO - Purdue University; Selling, Gordon; CAMPANELLA, OSVALDO - The Ohio State University; JONES, OWEN - Purdue University

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2021
Publication Date: 1/27/2021
Citation: Federici, E., Selling, G.W., Campanella, O.H., Jones, O.G. 2021. Thermal treatment of dry zein to improve rheological properties in gluten-free dough. Food Hydrocolloids. 115. Article 106629. https://doi.org/10.1016/j.foodhyd.2021.106629.
DOI: https://doi.org/10.1016/j.foodhyd.2021.106629

Interpretive Summary: There is a growing need for gluten free bread products. The ability of wheat to form protein filaments which allows bread to rise and maintain its shape is difficult to mimic. Many gluten-free breads either do not rise well, have very large pores or are too soft/firm. It has been shown that corn protein (zein) after heat and mixing in an extruder gave high quality gluten-free breads. Research was put forth to determine if using heat alone would provide the required structural modifications in the protein to give a good bread. Before bread can be produced, the quality of the bread dough must be first examined. Zein was heated at various temperatures and then bread dough was produced and evaluated using a variety of techniques. It was determined that treating zein at 320 F provided a good quality bread dough. Efforts are in progress to determine if quality breads can be produced using dough using heat treated zein. This research will be valuable to all participants in the corn processing value chain. In addition, companies (and the ultimate consumer) interested in producing or using gluten-free products will also benefit.

Technical Abstract: Zein is a gluten-free storage protein from corn that provides extensibility to starch-based doughs. However, as-is zein does not confer elastic behavior, a fundamental feature to produce high quality bread. Previous research showed that extrusion above 140 C can improve zein dough elasticity through the generation of a high molecular weight fraction. To determine whether thermal treatments could similarly improve zein function in doughs, zein was heated in a standard or vacuum oven at temperatures of 160-200 C. Gel electrophoresis of treated samples showed that thermal treatment promoted development of higher molecular weight zein fractions. Furthermore, increasing thermal treatment temperature led to increased beta-sheet content and improved elasticity of hydrated zein masses. Doughs prepared from rice starch using zein treated at 160 C possessed improved elastic properties, but zein couldn’t elongate into fibrils when sheared or improve dough properties after higher temperature treatments. Controlling heat-induced cross-linking and structural rearrangement of zein enhances function in gluten-free dough.