Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2005
Publication Date: 3/12/2005
Citation: Robertson, G.H., Gregorski, K.S., Cao, T. 2005. Changes in secondary protein structures during mixing development of high absorption (90%) flour and water mixtures. Cereal Chemistry, 83:136-42. Interpretive Summary: Advanced separation technology will facilitate the participation of wheat as a biorefined substrate to meet national needs for biofuels and biobased products. This manuscript is one of a series evaluating fundamental properties related to the ability to separate wheat gluten from starch. Here we applied Fourier transform infrared reflectance spectroscopy to identify and characterize protein structure related to separability. We found that most secondary features of protein structure like sheet formation and folding change with mixing development and are in place when the flour is most separable. It is important to know what these structural changes are and when they occur to evaluate different mixing methodologies and to better manipulate the system for completeness of separation.
Technical Abstract: Wheat flour and water mixtures at 90% absorption 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) cell. 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, beta-turn, beta--strand, beta-sheet, and random conformations. The ratio of beta-sheet to non-sheet conformations reached its greatest value about the same time that the mixture was most effectively separated but before the peak consistency measured by a micro-Farinograph.