Abstract: In this study, soluble gelatin-chitosan composite was prepared by electrostatic bonding and it was further used as a carrier to prepare eugenol nanocapsules by self-assembly method. The preparation conditions were optimized using one-factor-at-a-time and orthogonal array design methods. Chitosan concentration, gelatin concentration, crosslinking time, rotation speed and eugenol concentration were used as independent variables whose effects on particle size and encapsulation efficiency were evaluated. The nanocapsules prepared under optimized conditions were characterized. The results showed that the optimal preparation conditions were determined as 2 mg/mL, 2 mg/mL, 5 mg/mL, 800 r/min and 30 min for chitosan concentration, gelatin concentration, eugenol concentration, rotation speed, and crosslinking time, respectively. The average particle size of the obtained eugenol nanocapsules was 229.09 nm and the encapsulation efficiency was 50.69%. The eugenol nanocapsules were uniform in size and regularly spherical in shape as characterized by TEM. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) showed that eugenol and gelatin interacted via hydrogen bonds and hydrophobic forces. Eugenol could be controlled released from the nanocapsules. In summary, the preparation process was simple, green and mild and could expand the application scope of eugenol and improve its bioavailability. The nano-encapsulation system has potential application in food preservatives.

Key words: eugenol, nanocapsules, self-assembly method, characterization