Acid-induced gelation of thermal co-aggregates from egg white and hempseed protein: Impact of microbial transglutaminase on mechanical and microstructural properties of gels

Abstract

The thermal co-aggregates from mixed egg white protein (EWP) and hempseed protein isolate (HPI), named mixed EWP/HPI aggregates, was produced by heating the mixture solutions (5.0% w/v) at different EWP/HPI weight ratios (0/100, 75/25, 50/50, 25/75 and 100/0) under alkaline pH. Subsequent, the acid gelation of the thermal aggregates was induced by adding glucono-δ-lactone (GDL). The thermal treatment at alkaline pH produced the aggregates assembled by both disulfide and non-disulfide covalent bonds, and they exhibited low viscosity, and high solubility EWP alone formed gels of high mechanical strength in the presence of GDL, whereas no gels were obtained from the thermal aggregates of HPI alone. The EWP/EWP aggregates of different EWP/HPI ratios formed acid-induced self-supported gels. With increasing HPI content, the elastic modulus, tan δ, creep performance, texture parameters, fracture stress/strain, and microstructural homogeneity of the mixed EWP/HPI gels tended to decrease. Treatment with transglutaminase (TGase) relatively improved the mechanical properties of mixed gels, but not enough to completely off-sets the weakening effects. This research has offered insight into the fabrication of cold-set gels from different protein aggregates and the generated information may provide the opportunity to develop functional food formulations enriched in plant proteins.