Protein–protein interactions of a whey–pea protein co‐precipitate
Heidi Thorgaard Kristensen, Mette Christensen, Mikka Stenholdt Hansen, Marianne Hammershøj, Trine Kastrup Dalsgaard
Abstract
Summary The aim of this study was to investigate the mechanisms behind protein–protein interactions in a co‐precipitate of whey protein isolate (WPI) and pea protein isolate (PPI). A co‐precipitate and blend, consisting of 80% WPI and 20% PPI, were compared. Covalent disulphide interactions were studied by blocking of free thiols with N ‐Ethylmaleimide (NEM), while electrostatic interactions were studied in systems with 0.5 m NaCl and hydrophobic interactions with 0.2% SDS. Protein solubility, stability and secondary, tertiary and quaternary protein structures were analysed. Co‐precipitation did not introduce different protein–protein interactions than the direct blending of proteins. SDS affected solubility ( P < 0.05), secondary and tertiary structure. However, the effects of NEM and NaCl were significant greater ( P < 0.05) on the same parameters and thermal stability, especially when combined ( P < 0.01). Thus, the protein–protein interactions in a whey–pea co‐precipitate and protein blend consisted of disulphide bonds and electrostatic interactions.