Eco-friendly antimicrobial biodegradable films synthesized from pineapple leaf and Japanese sweet potato skin starch for food packaging applications

Biodegradable starch-based films produced from agricultural waste represent a sustainable alternative to petroleum-derived food packaging materials. In this study, starch extracted from pineapple leaves (Ananas comosus) and Japanese sweet potato skins (Ipomoea batatas) was incorporated with chitosan to develop antimicrobial biodegradable films using a gel-casting technique. The prepared films were characterised for their mechanical, thermal, swelling, solubility, structural, morphological, antimicrobial, and food-preservation properties. From the various formulations, the 10% starch-chitosan PA-L film displayed the best performance, with an optimum tensile strength of 19.8 ± 1.2 MPa, elongation at break of 25.3 ± 1.5%, thermal resistance of 95 ± 2°C, swelling degree of 120 ± 3%, and water solubility of 28.7 ± 1.5%. X-ray diffraction and Fourier transform infrared spectroscopy confirmed the successful formation of a semi-crystalline chitosan-starch composite through intermolecular interactions, while scanning electron microscopy revealed compact and homogeneous film morphology. The PA-L film demonstrated higher antimicrobial activity, producing inhibition zones of 14, 10, 10, and 8 mm against Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, respectively. In comparison, the JSP-S film exhibited inhibition zones of 12, 0, 6, and 6 mm against the respective bacterial strains. In the shelf-life studies, the optimised PA-L film confirmed an extended storage life of lemons and ivy gourds for 10 days under ambient storage conditions by reducing the moisture loss and delaying visible spoilage. Weight loss was reduced from 32.7% to 6.7% for lemons and from 32.3% to 11.4% for ivy gourds when wrapped with the PA-L film. These findings suggest that starch-based biodegradable films that are derived from agricultural waste like pineapple leaves and Japanese sweet potato skins and reinforced with chitosan could serve as a sustainable food packaging material capable of extending the shelf life and maintaining the quality of fresh food produce.