Lipophilization of chitin as novel polymeric stabilizer for improved oil-in-water emulsions

To develop novel polymeric emulsifiers/stabilizers for improved functionalities, an array of chitin fatty acid esters (chitin octanoate, laurate, palmitate, and stearate) were synthesized using a trifluoroacetic anhydride (TFAA)/methanesulfonic acid (MSA) catalytic system. The synthesized products were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC); successful lipophilization of chitin was confirmed by analysis results of FTIR, NMR, and DSC, with the degree of substitution (DS) of the products that ranged from 0.89 to 1.05. Ten percent fish oil-in-water emulsions were prepared using the synthesized chitin fatty acid esters, and characteristic properties (droplet size, zeta potential, and creaming stability) were determined. It turned out that chitin octanoate and chitin laurate were capable to solely enable homogeneous nanoemulsion (200–240 nm, polydispersity index 0.22–0.26), with excellent stability (no creaming after 14-day storage), which may find great potential applications in food, biomedical, and cosmetics sectors.