Effect of zein extrusion and starch type on the rheological behavior of gluten-free dough

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

Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2019
Publication Date: 11/2/2019
Citation: Federici, E., Jones, O.G., Selling, G.W., Tagliasco, M., Campanella, O. 2019. Effect of zein extrusion and starch type on the rheological behavior of gluten-free dough. Journal of Cereal Science. 91(2020)102866. https://doi.org/10.1016/j.jcs.2019.102866.
DOI: https://doi.org/10.1016/j.jcs.2019.102866

Interpretive Summary: This research demonstrated that improved bread dough can be made using corn protein. Most bread is made from wheat flour. Wheat flour is a mix of wheat starch and wheat protein (this protein component , gluten, is that which is implicated in celiac disease) and when wheat flour is mixed with other materials, a bread dough can be produced. There is a need to provide improved gluten-free breads to meet the needs of the those suffering from celiac disease. These non-wheat containing breads may also have value in locations (such as Asia or Africa) which do not have a local supply of wheat. Research was carried out by a team composed of scientists from Purdue University and the USDA Agricultural Research Service where corn protein (zein) was used in combination with starch from plants other than wheat to provide higher quality bread doughs. Starch from corn, potato, and rice were mixed with zein. The zein was used as isolated and after melt processing. Melt processing is carried out using an extruder, as such processing is commonly used for making breakfast cereals (corn pops) or snack foods (corn puffs). It was found that structures built within the corn protein during melt processing were bale to provide improved bread doughs. When melt processed zein was combined with rice starch, it gave a dough with similar properties as wheat. The ability to make a high quality dough is the first step in the process for producing a high quality bread. Thus this research will benefit people having sensitivites to gluten or to bread producers taht have limited access to wheat.

Technical Abstract: Previous research has shown that zein above its glass transition temperature may adopt specific molecular structures that form doughs with viscoelastic properties comparable to those of wheat gluten. With the hypothesis that extrusion promotes molecular changes in zein and favor interactions with starches that enhance dough viscoelasticity, the effects of extruding zein at 90-160°C on the rheological properties of doughs prepared with potato, rice, and corn starches were determined. Formulations were optimized to provide similar mixograph profiles to that of a standard wheat dough. For all zein-types, creep-recovery tests demonstrated that doughs prepared with corn and potato starches were less elastic, while doughs prepared with rice starch were comparable to wheat-dough. Extensional tests showed that zein extruded at 160°C provided a larger increase in strain-hardening behavior and extensional viscosity, which is important for bread production. These samples also exhibited larger extensional stresses. Gel electrophoresis of zein extruded at 160°C revealed an increase in protein aggregates and smaller peptides when compared to samples subjected at lower extrusion temperatures. Scanning electron micrographs of doughs containing zein showed starch granules embedded within an amorphous material and fibrous structures attributable to elongated zein. This research shows a potential application of extruded zein in the production of gluten-free breads.