The invention discloses a preparation method of a
gelatin-
chitosan composite membrane. The method includes the steps that
chitosan is added into a three-opening flask at an indoor temperature, then deionized water is added, stirring is conducted for 3-5 minutes, an acid solution is added while stirring is conducted after the
chitosan is evenly dispersed, the pH value is adjusted to be 3.5-6, sufficient stirring is conducted continuously, and accordingly a chitosan solution is obtained; a
gelatin solution and the chitosan solution are mixed, and PEG 200 is added into the
gelatin / chitosan
mixed solution; afterwards, the solution is neutralized by a weak NaOH solution till the pH value is 6; transglutaminase (TGase) is added, stirring is conducted to enable gelatin and chitosan to undergo crosslinking, then the solution is heated to be boiled,
enzyme denaturalixation is carried out for 8-12 minutes, defoaming is conducted when the temperature of the solution is lowered to the indoor temperature, and membrane
casting is achieved. The time needed for dissolving the chitosan can be shortened obviously, efficiency is improved, and after the TGase undergoes catalytic crosslinking, the water
solubility,
swelling ratio and
moisture permeability of the gelatin-chitosan
composite membrane are lowered. The gelatin-chitosan
composite membrane can play obvious antibacterial and fresh-keeping effects when being used for packaging fruits.