Oleogels based on protein fibrils-hordein-xanthan gum complexes: Formation, structure, and physicochemical properties

Recently, oleogelators derived from natural biopolymers have received greater interest. In this study, whey protein isolate fibril (WPIF), ovalbumin fibril (OVAF), soybean protein isolate fibril (SPIF) and pea protein isolate fibril (PPIF) were used as structural agents and separately combined with hordein and xanthan gum (XG), to fabricate oleogels via emulsion template method. The TEM results of the complexes illustrated the crosslinked fibril networks were formed with hordein as the corresponding junctions, where XG coated on the fibril-hordein complex surface in nanoparticles. Hydrogen bonds and hydrophobic interactions were the main driving forces in the formation of fibrils-hordein binary complexes, and XG adhered to the binary complexes via electrostatic attraction. Fibrils affect the formation of oleogels by different interfacial behaviors of emulsions. The CLSM results revealed that oleogel based on OVAF had the densest network, followed by WPIF-, PPIF- and SPIF-based oleogels. Furthermore, the sequence of oil binding capacity, storage/loss modulus, viscosity, and hardness of the oleogels exhibited similar trends with that of the network density. In comparison with soybean oil, the release rates of the free fatty acids in the oleogel systems were notably reduced. This study provided new insights for developing protein fibrils-based oleogels.