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Farinograph Responses for Wheat Flour Dough Fortified with Wheat Gluten Produced by Cold-Ethanol or Water Displacement of Starch

¹Process Chemistry and Engineering Research Unit, Western Regional Research Center, Pacific West Area, United States Department of Agriculture, Agricultural Research Service, 800 Buchanan Street, Albany, CA 94710. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. E-mail: grobertson@pw.usda.gov Phone: 510-559-5866. Fax: 510-559-5818.

The objective of this research was to identify and define mixing characteristics of gluten-fortified flours attributable to differences in the method for producing the gluten. In these studies, a wheat gluten concentrate (W-gluten) was produced using a conventional process model. This model applied physical water displacement of starch (dispersion and screening steps), freeze-drying, and milling. W-gluten was the reference or “vital” gluten in this report. An experimental W-concentrate was produced using a new process model. The new model applied coldethanol (CE) displacement of starch (dispersion and screening steps), freeze-drying, and milling. Freeze-drying was used to eliminate thermal denaturation and thereby focus on functional changes due only to the separation method. The dry gluten concentrates were blended with a weak, low-protein (9.2%), soft wheat flour and developed with water in a microfarinograph. We found that both water and cold-ethanol processed gluten successfully increased the stability (St) and improved mixing tolerance index (MTI) to create in the blended flour the appearance of a breadbaking flour. Notably, in the tested range of 9–15% protein, the St for CE-gluten was always higher then the St for W-gluten. Furthermore, the marginal increase in St (slope of the linear St vs. protein concentration) for the CE-gluten was ≈57% greater than that for the W-gluten. The slope of the MTI vs. protein data was lower for the CE-gluten by 24%. Flour fortified with CE-gluten exhibited higher water absorption (up to 1.8% units at 13.5% P) than flour fortified with W-gluten.