Development of Schiff base–type oleogels using the emulsion template approach at different pH values: Comparative investigation of their structure and properties

Herein, Schiff base-type oleogels (SBOs) comprising chitosan (CS) and syringaldehyde (SA) were prepared using the emulsion template method at different pH values. The properties and structure of the oleogels produced at various pH values were examined. ATR-FTIR and X-ray diffraction findings indicated that CS was cross-linked with SA to produce Schiff bases. The Schiff base reaction was the primary reason for the successful formation of oleogels. Rheological performance revealed that all oleogels had high gel strength (G' > G″) and thermal stability. Additionally, free radical scavenging experiments and oil-binding capacity (OBC) indicated that the CS-SA oleogels had excellent antioxidant properties and OBC when the pH was 4,which can be attributed to the good solubility of chitosan in this pH environment, and the relatively stable Schiff base structure. However, even at lower pH (below pH of 4), the cross-linking reaction between CS and SA still occurred. Thus, the liquid oil was successfully retained in the 3D network structure.