Localization of puroindoline-a and lipids in bread dough using confocal scanning laser microscopy

Puroindolines are lipid-binding proteins from wheat flour that play a significant role in bread crumb texture. The localization of wheat flour lipids and puroindoline-a (PIN-a) in bread dough was studied by confocal scanning laser microscopy (CSLM). Wheat lipids were located around gas cells (GC) and embedded within the protein-starch matrix (SPM) of the dough. PIN-a was mainly located in the matrix of dough, where it was associated with lipids. In contrast, in defatted dough, PIN-a was found around GC. Addition of puroindolines in bread dough induced a defatting of the gas bubble surface and a decrease of the lipid vesicles and/or droplet size embedded within the SPM. Therefore, puroindolines control the lipid partitioning within the different phases of dough, a phenomenon that should have important consequence on the gas bubble expansion and GC formation in the further stages (fermentation, baking) of the bread-making process.