Production of Antimicrobial Chitosan–Pistachio Gum Composite Film for Bio-Bag Fabrication

Functional edible films are thin polymeric layers used in food packaging to enhance product quality and shelf life. In the present study, pistachio gum and chitosan were combined to create a functional edible film. Chitosan was locally produced from fungal biomass of Aspergillus niger ATCC 16404 and characterized using Fourier-transform infrared spectroscopy (4000 ̶ 400 cm ̶1). The optimal concentrations of pistachio gum, glycerol (as plasticizer), and emulsifier were found by preparing 18 distinct film formulations. The prepared films were tested for their thickness, tensile strength, elongation at break, tear strength, air permeability, water vapor permeability (WVP), solubility, field emission scanning electron microscopy (FE ̶ SEM), and thermogravimetric analysis (TGA). The incorporation of pistachio gum substantially improved film characteristics, resulting in increased thickness from 0.13 to 0.22 mm, tensile strength up to 1.40 MPa, elongation at break of 88.07%, and tear strength of 1.73 N, suggesting more flexibility and mechanical stability. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of film solutions were evaluated against clinical multidrug-resistant (MDR) Escherichia coli and Staphylococcus aureus using the broth microdilution method. The chitosan-gum combination exhibited better antibacterial activity than chitosan alone. The antifungal activity was studied against A. niger; The chitosan-gum combination resulted in complete inhibition of A. niger growth. Additionally, the prepared chitosan-gum films exhibited lower solubility in water, acidic and alkaline solutions. Bags were successfully fabricated from chitosan with pistachio gum films. The incorporation of gum led to a more compact morphology, enhanced sealing performance, and improved functional performance.