Fabrication, structure, characterization and emulsion application of citrate agar.

Citric acid esterified agar (CA) with different degrees of substitution (DS) was prepared, and CA gel was used to stabilize O/W emulsions. Compared with native agar (NA), CA had lower gel strength, higher transparency, and higher water contact angle. Further analysis of DS, group content ratio, Fourier transform infrared, and nuclear magnetic resonance data showed that the CA underwent cross-linking reaction. Emulsion properties revealed that CA gel emulsion (CAGE) had smaller particle size and lower ζ-potential than the NA gel emulsion (NAGE). Meanwhile, confocal laser scanning microscopy confirmed that CA gel stabilized emulsions by forming a protective film around the oil droplets. Stability tests showed that CAGE (prepared with CA gel [DS = 0.145]) was more stable than NAGE at pH 3-11. Rheological results further confirmed that emulsion stability was influenced by electrostatic repulsion and gel adsorption. The application prospect of CAGE was evaluated by encapsulating vitamin D3 and curcumin.