Development of bioactive and environmentally friendly chitosan-based film using waste of pistachio dehulling process as a novel promising food packaging material.

Chitosan films containing different amounts of pistachio hull methanol extract (PHE) (2 %, 4 %, 8 % w/v) were produced. LC-MS/MS analysis demonstrated that tannic acid (207.74 mg/g PHE), gallic acid (46.63 mg/g PHE), protocatechuic acid (27.79 mg/g PHE), quinic acid (16.41 mg/g PHE), isoquercitrin (15.2 mg/g PHE) were the most abundant phenolic compounds in PHE. The biological activity test results indicated that PHE enhanced the antioxidant and antibacterial activities of chitosan films. Chitosan-based films with 8 % PHE showed significant antimicrobial activity on all microorganisms tested. Chitosan films containing even the lowest concentration of PHE effectively inhibited DPPH free radicals, indicating a significant antioxidant activity. The increase in the amount of PHE caused a decrease in the L* value and an increase in the a* and b* values. It was found that the tensile strength and elongation at break of the films containing PHE were higher than those of the control film. Chitosan film with 4 % PHE exhibited the highest values of tensile strength (10.72 ± 1.06 MPa) and elongation at break (198.57 ± 10.34 %). FTIR analysis showed that PHE modified the intermolecular interactions in the film matrix, leading to the expansion of the CC bond and an increase in the intensity of the CO bands. Thermal analysis displayed that chitosan films incorporating PHE exhibited higher thermal stability compared to control films. PHE can be used as a bioactive supportive material in food packaging.