Preparation, structural characterization and in vitro digestibility mechanism of walnut oil body emulsion gels based on crosslinking of edible polysaccharide and vanillin

Oil bodies (OB) are naturally occurring pre-emulsified oil droplets with broad application prospects in emulsions and gels. In this study, the chitosan and vanillin with different concentrations were used as structuring agents for preparation of oleogels based on walnut OB (WOB), and the particle size, zeta potential, spectral, thermal characteristics, physical properties and in vitro simulated digestion of WOB oleogels were evaluated. These characteristics results showed that chitosan and vanillin were successfully cross-linked with WOB and formed a dense three-dimensional network structure. Spectral analysis results demonstrated that chitosan and vanillin could improve WOB properties mainly through hydrogen bond interaction, Schiff base crosslinking and electrostatic interaction. The physical properties analysis manifested that the cross-linked WOB oleogels had strong hardness (26.86 N), good thermal stability (ΔH = −442.16 J g -1 ), excellent structural recovery (0.90) and higher gel strength (G′> 9000 Pa). In vitro simulated gastrointestinal digestion manifested that cross-linking reduced the free fatty acids released from oleogels. The microstructure of digestates illustrated that this might be related to the compact coating formed by chitosan and the integrated network induced by vanillin. This study provided a novel strategy for using WOB to replace animal fats to produce healthy oleogels.