Drying temperature effects on oil dispersion and properties of alginate-kiwi seed oil films

Abstract

This study evaluated the effects of drying temperatures (25, 30, 40, and 60 °C) on the oil dispersion and physicochemical properties of sodium alginate–kiwi seed essential oil composite films, including their drying kinetics, oil distribution, morphology, mechanical strength, thermal stability, and barrier properties. The drying temperature significantly influenced the physical integrity and oil dispersion of the film. A drying temperature increased from 25 to 60 °C reduced film thickness from 54.1 to 43.3 μm, increased water vapor permeability from 5.0 × 10⁻¹¹ to 5.9 × 10⁻¹¹ g m⁻² s⁻¹ Pa⁻¹, and adversely affected ultraviolet light barrier properties, while enhancing transparency and having no notable effect on moisture content. Confocal laser scanning microscopy, scanning electron microscopy, atomic force microscopy, and X-ray diffraction analysis revealed that low temperature drying enhanced homogeneity, compactness, and crystallinity. Mechanical properties, including tensile strength (1.6–2.23 MPa) and elongation at break (70.9 %–93.6 %), improved with the increasing temperatures up to 40 °C but declined thereafter. These findings highlighted the influence of drying temperature on the functional properties of the composite films, suggesting that low drying temperatures of 25–30 °C are optimal for maintaining the desirable structural and functional characteristics for food packaging applications.