Protein changes during various stages of breadmaking of four spring wheats: Quantification by size-exclusion HPLC

Protein changes for four hard red spring wheat genotypes (Len, Marshall, 215, and Butte 86) were assessed at various stages of breadmaking using a size-exclusion HPLC technique. Breadmaking stages considered were flour, after mixing, before punching, after punching, after fermentation, and after proofing. Quality and functional characteristics of the four wheat genotypes were determined. The three main protein groups isolated by SE-HPLC were further characterized by SDS-PAGE. A direct relationship between polymeric glutenin (peak I of SE-HPLC fractions) in flours and loaf volume was found for the three wheat genotypes with identical high molecular weight glutenin subunit (HMW-GS) composition (2*, 7+9, 5+10) and one line with similar HMW-GS composition (2*, 7+9, 2+12), differing in the Glu-DI locus. Quantitative changes in the distribution of SDS-soluble proteins fractionated by SE-HPLC were also examined. Peak I proteins (polymeric proteins) from SDS-extractable proteins tend to decrease during breadmaking, while peak III proteins (low molecular weight) tend to increase. Peak II (monomeric proteins, medium molecular weight) did not show a change in quantity during breadmaking. These results seem to indicate that some type of rearrangement took place during the breadmaking process to release proteins of smaller molecular weight.