Physicochemical and functional enhancement of κ-carrageenan films with olive oil for biodegradable active food packaging

Abstract

This study investigates the incorporation of olive oil at concentrations of 1.5%, 3.0%, and 4.5% into κ-carrageenan films to improve their physicochemical and antioxidant properties. Olive oil at 4.5% significantly (p < 0.05) reduced water solubility by 26%, although it also elevated water vapor permeability and opacity. Similarly, 4.5% olive oil also resulted in significant (p < 0.05) improvements in light barrier properties, particularly at wavelengths of 200, 280, and 400 nm. While tensile strength decreased with the incorporation of olive oil, elongation at break increased significantly (p < 0.05), enhancing film flexibility. Thermal analysis indicated an elevation in melting temperature, peaking at 104.75°C for films with 4.5% olive oil. Confocal laser scanning microscopy (CLSM) revealed that a 1.5% oil concentration produced the most homogeneous structure. Antioxidant analysis showed increased (p < 0.05) total phenolic content (22.02 mg GAE/100 g at 4.5% olive oil), with a corresponding rise (p < 0.05) in DPPH radical scavenging activity and ferric reducing antioxidant power (FRAP). Overall, these enhancements suggest that olive oil not only improves the physical integrity but also adds functional antioxidant benefits to κ-carrageenan films, highlighting their potential for active food packaging applications.

Highlights

• Olive oil enhances κ-carrageenan film flexibility and antioxidant properties.
• Increased olive oil reduces solubility but raises water vapor permeability.
• Higher olive oil concentrations increase film opacity and thermal stability.
• Confocal microscopy shows a homogeneous film at low olive oil concentration.
• κ-carrageenan-olive oil film is a promising active food packaging material.