Gamma-irradiated PVA/chitosan/moringa extract edible coatings for postharvest quality and insect control in Siwi dates

Abstract

Siwi dates are highly nutritious, versatile, and naturally energy-rich. However, prolonged storage often results in quality deterioration due to pests and microbial contamination, leading to texture changes, insect infestation, and loss of flavor and nutrients. To address these challenges, environmentally friendly preservation strategies have been explored to safeguard this valuable crop. In this study, we report the synthesis of a sustainable edible coating formulated from moringa extract (ME) incorporated into polyvinyl alcohol (PVA) and chitosan (CS) matrices, prepared via γ-irradiation. Different ratios of moringa extract (ME) (3, 5, 10, and 15%) were successfully incorporated into PVA/CS matrix to synthesize four distinct PVA/CS/ME coating solutions. For efficient characterization, PVA/CS/ME films containing 10% ME were fabricated using the casting method, and their properties were examined by FTIR, XRD, and tensile testing. FTIR and XRD analyses confirmed the effective interaction between ME and the PVA/CS matrix. Increasing the ME concentration within the PVA/CS matrix imparted significant antibacterial activity against Staphylococcus aureus and Escherichia coli , attributed to ME phytochemicals, thereby highlighting the films’ potential as active food packaging materials that enhance safety and extend shelf life. Furthermore, four PVA/CS/ME coating solutions were applied as edible coatings to extend the shelf life and maintain the quality of Siwi dates during 6 months of storage at room temperature (65–70% RH). Quality parameters, including insect infestation (%), weight loss (%), moisture content (%), browning index, total soluble solids, and pH, were monitored throughout the storage period. The coating solution containing 15% ME demonstrated the most pronounced effect, effectively reducing insect infestation and preserving fruit quality. These findings highlight a promising eco-friendly approach for the long-term preservation and marketing of Siwi dates.