Effects of chestnut shell extract and citric acid on the properties of navel orange pomace/chitosan composite films

The improper use of citrus peel and nondegradable plastic film can cause substantial issues, such as environmental pollution and resource waste. Herein, navel orange pomace powder (NOPP) and chitosan (CS) were used as the raw material and film-forming additive, respectively, to prepare biobased composite films. Chestnut shell extract (CHE) and citric acid (CA) were added to the prepared NOPP/CS biobased multifunctional films. Based on ensuring the tensile strength of the film above 10 MPa, the elongation at break of the film can be increased from 19.11 % to 34.93 %, the water contact angle can reach 60°, and the water vapor transmittance can be significantly reduced to approximately 1.1 × 10^-10 gs^-1m^-1Pa^-1. Additionally, the antibacterial ability and antioxidant capacity of the composite film were improved. We observed that the multifunctional film could significantly inhibit the browning of fresh-cut apples, where the browning index was maintained between 60 and 65, which was 25 % lower than that of the control. The newly developed film therefore possesses the potential to replace the traditional plastic cling film. This research contributes to the literature regarding the source of raw materials for biobased materials and highlights the value of navel orange processing by-products.