Active pectin–chitosan films from Spanish lime (Melicoccus bijugatus) shell pectin containing Pimenta racemosa essential oil nanoemulsions for sustainable food packaging

Abstract

In response to the widespread use and environmental impacts of conventional plastic food packaging, there is growing interest in biodegradable alternatives derived from renewable resources, including agricultural waste. Although pectin is widely investigated for sustainable packaging applications, it is predominantly sourced from citrus and apple by-products, while tropical agro-waste streams remain comparatively underexplored as alternative pectin sources. This study investigated pectin extracted from Spanish lime ( Melicoccus bijugatus ) shell waste as a polymer source for pectin-chitosan films incorporating nanoemulsified Pimenta racemosa essential oil (BLEO) for potential fresh-produce packaging applications. The films were characterized for structural, mechanical, barrier, antioxidant and antimicrobial properties, and their preliminary applicability was assessed qualitatively using tomatoes. BLEO incorporation (0.5–1.5%) increased antioxidant activity by up to fivefold and enhanced antimicrobial activity against Escherichia coli, Salmonella spp . and Listeria monocytogenes compared with the control film (0% BLEO). FTIR and XRD analyses indicated that the BLEO modified the polymer network, resulting in reductions in tensile strength from 16.20 to 6.88 MPa and Young’s modulus from 597.91 to 133.65 MPa, while elongation at break increased from 12.86% to 20.48%. Oxygen permeability increased from 1.05 to 8.02 cm 3 μm m -2 d -1 kPa -1 , whereas water vapor permeability exhibited a non-linear response. In the preliminary tomato storage assessment, coated fruit showed delayed visual ripening and less visible surface deterioration than uncoated controls after 21 days of ambient storage. Unlike many previous pectin-based packaging studies that have relied on commercial or conventional citrus- and apple-derived pectin, this study demonstrates the feasibility of using pectin extracted from M. bijugatus shell waste to develop active biodegradable films with tunable physicochemical and bioactive properties. This approach contributes to the valorization of underutilized tropical agro-waste within a circular bioeconomy framework and highlights its potential for fresh-produce packaging; however, quantitative postharvest studies are required to validate shelf-life extension and assess commercial applicability.