INTERACTION OF PUROINDOLINES WITH WHEAT-FLOUR POLAR LIPIDS DETERMINESTHEIR FOAMING PROPERTIES

The interaction of puroindolines with wheat polar lipids and the stabi lity of the corresponding puroindoline foams were investigated. Wherea s puroindoline-a is capable of binding tightly to both wheat phospholi pids and glycolipids, puroindoline-b interacts tightly only with negat ively charged phospholipids and forms loose lipoprotein complexes with glycolipids. Both ionic, hydrogen, and hydrophobic bonds contribute t o the stability of puroindoline-polar lipid complexes, and the integri ty of tryptophan-rich domain is essential for the interaction with neu tral polar lipids. Compared with egg white proteins, chosen as a model of nonlipid binding and good foaming food proteins, puroindolines exh ibit excellent foam stability, especially in the presence of wheat pol ar lipids. The higher efficiency of puroindoline-a than puroindoline-b to prevent foam destabilization by wheat polar lipids highlights the close relationships between lipid binding and foaming properties of th ese wheat proteins. These results indicate that puroindolines would be good candidates to play a major role in the formation and stability o f bread dough foams.