Proteomic characterisation of wheat protein fractions taken at different baking conditions

Food processing conditions affect the structure, solubility and therefore accurate detection of gluten proteins. We investigated the influence of dough, bread and pretzel making on the composition of different wheat protein fractions obtained by Osborne fractionation, which is based on solubility. The albumin/globulin (ALGL), gliadin and glutenin fractions from flour, dough, crispbread, bread and pretzel were analysed using RP-HPLC, SDS-PAGE and untargeted nanoLC-MS/MS. This approach enabled an in-depth profiling of the fractionated proteomes and related compositional changes to processing conditions including mixing, heat and alkali treatment. The ALGL fractions contained 71 protein groups, the gliadin fractions 27 and the glutenin fractions 47, of which 16 were common in all fractions. Label-free quantitation revealed that the relative abundances of 78 proteins were significantly affected by baking in the fractions of bread crumb and bread crust in comparison to flour.