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Substitution of Concentrated Ethanol for Water in the Laboratory Washing Fractionation of Protein and Starch from Hydrated 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.

An unprecedented, ethanol-based, washing process was used at a laboratory scale to produce both concentrated protein and starch fractions from hydrated wheat flour. In this multistep process, flour was first hydrated and mixed to a batter and then chilled and rested. The cold batter was then mixed and washed in chilled and concentrated ethanol using a modified device that normally applies the water-based Martin process. Control of the separation was affected by each of these steps. For instance, the hydration of the flour, the time of mixing, the temperature of the wash, the ethanol concentration, and the time of washing were influential. The method produced a gluten concentrate similar in yield and protein content to that reported for a pilot-scale Martin process but without the need for added salt. Notably, ethanol washing resulted in nonsticky, partially disintegrated curds that dried easily, whereas water washing resulted in a sticky, glutinous, cohesive mass that dried slowly. The process has commercial potential to reduce water and energy use, reduce wastewater generation and environmental impact, and improve product recovery. The process also has the potential to reduce the capital complexity of the drying step and create convenient opportunities for protein subfractionation.