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Relationships of Quality Characteristics with Size-Exclusion HPLC Chromatogram of Protein Extract in Soft White Winter Wheats

¹USDA-ARS-RRVARC-NCSL, Cereal Crops Research Unit, Wheat Quality Lab, Fargo, ND. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by Department of Agriculture and does not imply its approval to the exclusion of other products that also may be suitable. ²Corresponding author. E-mail: jae.ohm@ars.usda.gov ³Dept. of Crop & Soil Science, Oregon State University, Corvallis, OR. ⁴USDA-ARS, Western Wheat Quality Lab, Pullman, WA.

This study investigated relationships between molecular weight distributions of unreduced grain proteins and grain, flour, and end-use quality characteristics of soft white winter wheats grown in Oregon. Absorbance area and area percentage values of protein fractions separated by size-exclusion HPLC (SE-HPLC) showed significant correlations with quality characteristics, indicating associations of molecular weight distributions of proteins with quality characteristics. Specifically, high molecular weight polymeric protein fractions appeared to have a detrimental effect on soft wheat quality. This was shown by significant positive correlations with single kernel hardness index, and mixograph water absorption and tolerance, and negative correlations with break flour yield, cookie diameter, and cake volume. Higher proportions of soluble monomeric protein fraction eluted after the main gliadin peak, were associated with soft wheat quality due to negative associations with single kernel hardness index and mixograph water absorption and tolerance, and positive associations with break flour yield, cookie diameter, and cake volume. Calibration models were developed by the application of multivariate analyses to the SE-HPLC data. These models explained >90% of the variation in mixograph water absorption and cookie diameter and thickness.