Valorization of onion peels into sustainable preservative films for enhanced food shelf-life

Abstract

Plastic pollution, food wastage due to spoilage, and the underutilization of agricultural byproducts cause an increasing burden to the global food system. This study presents a solution to achieve a sustainable food technology by valorizing onion peels—an abundant agro-waste—into biodegradable, preservative-active packaging films. In this study, two distinct combinations of polymer matrices were developed: (i) 0.3% gellan gum and 0.3% xanthan gum (film G) and (ii) 0.3% guar gum and 0.5% sodium alginate (film O). These films, when blended with onion peel extract (OPE), showed potential to exhibit natural preservative properties. The detailed characterization of OPE-blended films was performed by FTIR spectroscopy, XRD, SEM, and TGA. OPE-blended films were more ductile and thermostable and had a higher UV resistance than the control films (without OPE), making them ideal for food storage. OPE exhibited a stronger antimicrobial activity than the commercial preservative sodium benzoate (SB), with lower MIC and MBC values against E. coli, B. megaterium, S. aureus, and C. albicans. Grapes coated with casting solutions of OPE-containing films G and O showed an extended shelf life up to 15 days at 25 °C, while blueberries packed in the OPE-blended films showed significantly reduced moisture loss. This innovation directly supports UN SDG 12 and UN SDG 8, ensuring sustainability and waste valorization. The novel combination of polymer matrices for sustainable food preservation shows immense potential in the food industry and the packaging sector.