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Endogenous and Enhanced Oxidative Cross-Linking in Wheat Flour Mill Streams

¹School of Food Science, Washington State University, Pullman, WA 99164-6376; affiliated with the USDA-ARS Western Wheat Quality Laboratory. ²USDA-ARS Western Wheat Quality Laboratory, Washington State University, Pullman, WA 99164-6394. 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. ³Corresponding author. Phone: +1.509.335.4062. Fax: +1.509.335.8573. E-mail: morrisc@wsu.edu

A better understanding of the variation in oxidative cross-linking potential among flour mill streams can improve flour quality through the formulating of superior flour blends, and hence end-product attributes. The purpose of this research was to study the variation of oxidative cross-linking among 10 Miag Multomat pilot mill streams from 31 hard, soft and club wheat cultivars using Bostwick viscosity measurements. Flour slurries were made with either water alone (to measure the endogenous oxidative cross-linking viscosity) or with added hydrogen peroxide-peroxidase (to measure the enhanced oxidative cross-linking viscosity). Hard cultivars tended to produce more viscous flour slurries for both water and peroxide-peroxidase viscosity measurements in most mill streams. Mill streams with high oxidative cross-linking potential were those with the largest differences between water and peroxide-peroxidase viscosity including 1st Break, 1st and 2nd Middlings, and 1st Midds Redust. Conversely, mill streams 3rd Break and 4th and 5th Middlings were the least likely to form oxidative cross-links. The ability to form oxidative cross-links is dependent on the availability of ferulic acid and tyrosine residues. Therefore, the arabinoxylan and protein polymers in mill streams that have a high oxidative cross-linking potential have a structure that is more conducive to forming oxidative cross-links.