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Mixograph Responses of Gluten and Gluten-Fortified Flour for Gluten Produced by Cold-Ethanol or Water Displacement of Starch from Wheat Flour

¹Process Chemistry and Engineering Research Unit, Western Regional Research Center, Pacific West Area, Agricultural Research Service, United States Department of Agriculture, 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. Phone: 510-559-5866. Fax: 510-559-5818. E-mail: grobertson@pw.usda.gov.

The total protein of gluten obtained by the cold-ethanol displacement of starch from developed wheat flour dough matches that made by water displacement, but functional properties revealed by mixing are altered. This report characterizes mixing properties in a 10-g mixograph for cold-ethanol-processed wheat gluten concentrates (CE-gluten) and those for the water-process concentrates (W-gluten). Gluten concentrates were produced at a laboratory scale using batter-like technology: development with water as a batter, dispersion with the displacement fluid, and screening. The displacing fluid was water for W-gluten and cold ethanol (≥70% vol, -12°C) for CE-gluten. Both gluten types were freeze-dried at -10°C and then milled. Mixograms were obtained for 1) straight gluten concentrates hydrated to absorptions of 123–234%, or 2) gluten blended with a low protein (9.2% protein) soft wheat flour to obtain up to 16.2% total protein. The mixograms for gluten or gluten-fortified flour were qualitatively and quantitatively distinguishable. We found differences in the mixogram parameters that would lead to the conclusion of greater stability and strength for CE-gluten than for W-Gluten. Differences between the mixograms for these gluten types could be markedly exaggerated by increasing the amount of water to the 167–234% range. Mixograms for evaluation of gluten have not been previously reported in this hydration range. Mixograms for fortification suggest that less CE-gluten than W-gluten would be required for the same effect.