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Water-Extractable Nonstarch Polysaccharide Distribution in Pilot Milling Analysis of Soft Winter Wheat

¹United States Department of Agriculture, Agricultural Research Service, Soft Wheat Quality Laboratory, Wooster, OH 44691. ²Corresponding author. E-mail: edward.souza@bayer.com ³Ohio State University, Ohio Agricultural Research and Development Center, Wooster, OH 44691.

Commercial wheat (Triticum aestivum em. Thell) flour milling produces flour streams that differ in water absorption levels because of variability in protein concentration, starch damaged by milling, and nonstarch polysaccharides. This study characterized the distribution of water-extractable (WE) nonstarch polysaccharides (NSP) in long-flow pilot-milling streams of soft wheat to model flour quality and genetic differences among cultivars. Existing reports of millstream analysis focus on hard wheat, which breaks and reduces differently from soft wheat. Seven soft winter wheat genotypes were milled on a pilot-scale mill that yields three break flour streams, five reduction streams, and two resifted streams. Protein concentration increased linearly through the break streams. WENSP concentration was low and similar in the first two break streams, which are the largest break streams. Flour recovery decreased exponentially through the reduction streams; flour ash and water-extractable glucose and galactose polymers increased exponentially through the reduction streams. Protein concentration and WE xylan concentration increased linearly through the reduction streams. The ratio of arabinose to xylose in WE arabinoxylan (WEAX) decreased through the reduction streams, and response varied among the genotypes. Flour ash was not predictive of stream composition among genotypes, although within genotypes, ash and other flour components were correlated when measured across streams. The second reduction flour stream was the largest contributor to straight-grade flour WEAX because of both the size of the stream and the concentration of WEAX in the stream.