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Title: Endogenous and enhanced oxidative cross-linking in wheat flour mill streams

Author
item RAMSEYER, DANIEL - Washington State University
item Bettge, Arthur
item Morris, Craig

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/2011
Publication Date: 4/28/2011
Citation: Ramseyer, D.D., Bettge, A.D., Morris, C.F. 2011. Endogenous and enhanced oxidative cross-linking in wheat flour mill streams. Cereal Chemistry. 88:217-222.

Interpretive Summary: Wheat grain processed by roller milling produces mill streams with very different characteristics. These characteristics are dependent on several factors including wheat variety, kernel hardness, tempering conditions and mill settings. Early reduction mill streams are primarily composed of pure, starchy endosperm. Later streams tend to have higher ash content due to bran contamination. The purpose of this research was to study the variation of chemical cross-linking among 10 flour mill streams from 31 hard, soft and club wheat varieties via Bostwick viscosity measurements. The differences in chemical cross-linking among mill streams may partially explain variation among flour blends and end-use quality.

Technical Abstract: The oxidative cross-linking of arabinoxylan and protein polymers is partially responsible for variation in end-use quality of wheat flour; specifically, differences in batter viscosity as well as variation in bread and cookie quality. 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. and understanding sources of variation in current flour blends. 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 varieties via 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). Mill streams with high oxidative cross-linking potential were those with the largest differences between water and peroxide-peroxidase viscosity; these included: 1st Break, 1st and 2nd Middlings, and 1st Midds Re-dust. 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 form oxidative cross-links.