Plant extracts such as pine nut shell, peanut shell and jujube leaf improved the antioxidant ability and gas permeability of chitosan films.

In order to develop the antioxidant and gas permeability packaging film, the effects of three plant extracts (pine nut shell, peanut shell and jujube leaf) on the physical, antioxidative and structural properties of chitosan based biodegradable films were studied. The results showed that three plant extracts improved the antioxidant capacity of films. The DPPH radical scavenging activity of chitosan-jujube leaf films increased by 3.8 times compared with the control films. The chitosan-pine nut shell films had the highest water vapor and oxygen permeability, while chitosan-peanut shell films showed greatest increase in CO2 permeability with a value of 1.71 × 104 cm3/(m2·24h) under standard test. In addition, three plant extracts reduced the homogeneity and caused porous structure of chitosan films. Chitosan-peanut shell films had the highest thermal stability compared with the control and other two films. X-ray diffraction and FTIR indicated three plant extracts changed the hydrogen bonding of film matrix and caused the changes of crystal and chemical structure. The study provided a reference for the preparation of polysaccharide-based active films with strong antioxidant and gas permeability.