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Changes in Secondary Protein Structures During Mixing Development of High Absorption (90%) Flour and Water Mixtures

¹Bioproduct 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

Wheat flour and water mixtures at 90% absorption (dry flour basis) prepared at various mixing times were examined using Fourier transform infrared (FT-IR) reflectance spectroscopy. Spectra were obtained using a horizontal attenuated total reflection (ATR) trough plate. The apparent amount of protein and starch on the surface of the dough varied with mixing time but this was likely due to the polyphasic nature of the substrate and the changing particle distributions as the batter matrix was developed. Deconvolution of the Amide I band revealed contributions from alpha helical, β-turn, β-strand, β-sheet, and random conformations. The ratio of β-sheet to nonsheet conformations reached its greatest value about the same time that the mixture was most effectively separated by a laboratory-scale, cold-ethanol-based method but before the peak consistency measured by a microfarinograph.