Development of multifunctional composite films based on κ-carrageenan/polyvinyl alcohol-polyethylene glycol copolymer blended with epigallocatechin gallate for strawberry preservation.

The rising demand for environmentally sustainable food packaging alternatives has led to the development of natural biopolymer based biodegradable films. In this study, we have developed a multifunctional composite film composed of κ-carrageenan (KC) and polyvinyl alcohol-polyethylene glycol graft copolymer (PVA-PEG, which exhibits intrinsic plasticizing attributes) as base film material. This composite film was reinforced by epigallocatechin gallate (EGCG) to address the functional limitations of developed KC/PVA-PEG (KCKB) films. The KC/PVA-PEG/EGCG 0.5% (KCKE 0.5%) films demonstrated sustained mechanical performance (7.1 ± 0.2 MPa), with improved surface hydrophobicity (72.3 ± 1.1°) and reduced water vapor permeability (0.9*10-7.g.mm/s.m2.Pa) in comparison to blank films (KCKB). The morphological, molecular and thermal characterization through SEM, 3D optical profilometry, FTIR, XRD, and TGA validated compatibility among film components and improved thermal stability. The optical analysis suggested increased opacity and reduced UV transmittance, contributing to the protection of food against UVdegradation. The KCKE 0.5% film exhibited significant antioxidant activity (~95% DPPH radical scavenging) and effective antibacterial potential against Escherichia coli (51.9% inhibition) and Staphylococcus aureus (75.3% inhibition) bacteria. The biocompatibility assay confirmed KCKE 0.5% films safety for food packaging applications. In preservation assessment, KCKE 0.5% effectively maintained visual appearance, weight, pH, and total phenolic content of stored strawberries. The soil burial test indicated ~60% physical disappearance of films within 42 days, supporting its environmental sustainability. These findings highlight the potential of KCKE composite film as an eco-friendly active packaging solution for food preservation applications.