Development and characterization of edible films from onion and garlic purees via continuous casting for scalable active food packaging

Edible films based on Allium purees, such as onion (Allium cepa L.) and garlic (Allium sativum L.), are a promising alternative for food packaging due to their high levels of polysaccharides, bioactive compounds, and intrinsic flavor, which enhance the sensory and functional properties of packaged foods. However, large-scale production is essential for these packaging materials to reach the final consumer. In this study, film-based purees were developed from hydrothermally pretreated onion and garlic, with or without carboxymethylcellulose (CMC), using both continuous casting and laboratory-scale bench casting methods. The properties of films produced by continuous casting were compared to those obtained by bench casting. Films containing CMC exhibited a more cohesive structure and improved mechanical performance (Tensile Strength (TS) increased by approximately 79%), higher contact angles (increased by approximately 112%), while water vapor permeability (WVP) and water solubility decreased by approximately 27% and 8.5%, respectively (p < 0.05 for all parameters), indicating better barrier properties. CMC also increased thermal stability, while the heat sealability of the films was unaffected by the production method. All films demonstrated strong antioxidant activity, regardless of their production method. These findings highlight the potential of CMC-enriched Allium-based edible films for packaging fatty foods prone to lipid oxidation. Hydrothermal pretreatment of whole Allium purees enhanced antioxidant properties, resulting in films with high antioxidant activity. Furthermore, the successful application of continuous casting demonstrates the feasibility of scaling up production, supporting the development of commercially viable bio-based packaging solutions.