DisplayTitle

A Rapid Method for Quantitation of Insoluble Polymeric Proteins in Flour¹

¹Cooperative investigations, U.S. Department of Agriculture, Agricultural Research Service, and the Department of Grain Science and Industry, Kansas State University. Contribution 98-81-J, Department of Grain Science and Industry, Kansas State Agricultural Experiment, Station, Manhattan, KS 66506. 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. ²Graduate research assistant and assistant professor respectively, Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. ³Biological technician, research leader, and research chemist respectively, USDAARS, Grain Marketing and Production Research Center, Manhattan, KS 66502. ⁴Corresponding author. E-mail: george@crunch.usgmrl.ksu.edu

The baking properties of several genotypes of U.S. hard wheats grown in state nurseries for the Wheat Quality Council (WQC) were analyzed by the Hard Winter Wheat Quality Laboratory. Flours (250 mg) from each individual line and location were extracted three times with 50% 1- propanol (1 mL) for 5 min each. Samples were vortexed continually during extraction. This method was effective in removing most monomeric proteins. Negligible detectable protein was found in the third extract. Significant amounts of polymeric glutenin were also extracted. Pellets were oven-dried (130°C) for 1 hr and analyzed for protein content using nitrogen combustion analysis. Protein remaining in the pellet consisted mainly of polymeric protein. The amount of gliadin and soluble polymeric protein could also be measured by separating the supernatant by size-exclusion chromatography. Good correlations between dough strength parameters and amounts of pellet protein and the relative amount of pellet protein (pellet protein/flour protein) were found for all samples. This procedure was simple and rapid, with the potential of analyzing large numbers of samples per day with good reproducibility.