Optimization of physicochemical properties of carboxymethyl chitosan/polyvinyl alcohol/curcumin edible antimicrobial films for food packaging application

Abstract

This study aimed to synthesize edible coating membranes composed of carboxymethyl chitosan/polyvinyl alcohol/curcumin nanoparticles (CMCS/PVA/Cur-NPs) using γ-irradiation, to extend the shelf life of sweet orange (Valencia) fruits stored at room temperature up to 70 days. CMCS/PVA/Cur-NPs membranes were fabricated via the casting method by blending the CMCS/PVA copolymer solution with 2.5% Cur-NPs. The mixture was subjected to thermal curing in an oven at 40°C until completely dried, after which the membranes were exposed to γ-irradiation at doses ranging from 5 to 25 kGy for subsequent characterization and evaluation in packaging applications. The chemical properties of CMCS/PVA/Cur-NPs membranes were analyzed using Fourier transform infrared spectroscopy (FTIR). In addition, the influence of γ-irradiation dose on gel content, water swelling behavior, mechanical properties, and antimicrobial activity was systematically investigated. Medium-sized Valencia oranges were packaged using CMCS/PVA/Cur-NPs membranes, sealed with Teflon tape, and stored under controlled conditions at room temperature (22°C ± 2°C) with relative humidity maintained at 65%–70% ± 5%. At the end of the storage period, coating efficiency was evaluated based on several quality parameters, including decay percentage, weight loss, pH, vitamin C content, total soluble solids (TSS), titratable acidity (TA), and the TSS/TA ratio. The results indicated that fruits coated with CMCS/PVA/Cur-NPs membranes retained superior external appearance and internal quality attributes compared to the uncoated control fruits. These findings demonstrate that CMCS/PVA/Cur-NPs membranes are effective and safe materials, highlighting their potential for application in food packaging to extend shelf life and preserve fruit quality.