Simplified Dilute Acetic Acid Based Extraction Procedure for Fractionation and Analysis of Wheat Flour Protein by Size Exclusion HPLC and Flow Field-Flow Fractionation

ABSTRACT A simple, highly efficient and reproducible two-step extraction procedure using dilute acetic acid without (AN) and then with sonication (AS) has been developed for the fractionation of wheat flour protein. Approximately 97% of total protein was extracted from a Canadian hard red spring wheat flour; an additional 1.2% protein could be recovered by further extraction with 1% DDT and 50% 1-propanol (AR). Size-exclusion HPLC (SE-HPLC) and flow field-flow fractionation (flow FFF) showed that the AN extract, which accounted for most of the total extractable protein (AN + AS + AR), consisted primarily of monomeric protein. The AS extract was composed primarily of polymeric proteins. Flow FFF showed that AN polymeric protein, including that eluting at the SE-HPLC void volume, showed smaller Stokes diameters than AS polymeric protein. Flow FFF profiles of AS SE-HPLC subfractions showed that the void volume subfraction contained monomeric and small polymeric protein in addition to large polymeric protein,...