Abstract: Based on mechanical properties of films including tensile strength and elongation at break, the preparation of chitosan-hexahydro-β-acids edible antibacterial films was optimize using one-factor-at-a-time method and orthogonal array design. The release behavior of hexahydro-β-acids from films was also investigated in ethanol aqueous solutions at concentrations of 95%, 75%, and 55% (V/V), respectively. Results showed that chitosan concentration exhibited the greatest effect on the mechanical properties of films, followed by interaction between chitosan and glycerol concentration. Drying temperature had the weakest effect. The optimized conditions were determined as follows: chitosan concentration 1.75 g/100 mL, drying temperature 40 ℃, and glycerol concentration 1.4%. The chitosan-hexahydro hexahydro-β-acids edible bacterial films prepared under these conditions showed the best mechanical properties with tensile strength and elongation at break of up to 29.26 MPa and 81.29%, respectively. The release of hexahydro-β-acids was gradually increased with increasing time and temperature, and stopped when the equilibrium was reached. According to the Peppas and Peleg equations, the release of hexahydro-β-acids in 95% ethanol followed Fick’s low of diffusion, but in 75% and 55% ethanol accorded with Peleg’s equation. The diffusion coefficient increased with rising temperature, and the most obvious release was found in 55% ethanol, which indicated that the water content and temperature in the release solvent were the key factors affecting the diffusion of the active ingredients.

Key words: chitosan, hexahydro-β-acids, edible antibacterial film, mechanical properties, release