Effects of Cuminaldehyde on the Structural, Mechanical, UV-Barrier, and Functional Properties of Gelatin/Konjac Glucomannan Edible Films

Cuminaldehyde (CA), a major bioactive constituent of cumin essential oil, was incorporated into gelatin/konjac glucomannan (Gel/KGM) composite films at different levels, expressed relative to the polymer content (mL/g polymer), to investigate its effects on film structure, physicochemical properties, and antioxidant activity. Structural characteristics of the films were examined using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Mechanical properties, surface wettability, optical properties, water sensitivity, and antioxidant activity were also determined. Spectroscopic analyses indicated changes in the molecular interactions of the Gel/KGM matrix following CA incorporation, while XRD and SEM analyses showed reduced structural order and a more heterogeneous microstructure at higher CA levels. Representative contact-angle observations showed an initial angle of 40.2° for the Control and 58.0° for CA-10, suggesting a tendency toward reduced surface wettability after CA incorporation. The addition of CA also improved UV-shielding properties and enhanced antioxidant responses, although the magnitude and trend of the antioxidant effect depended on the assay. In contrast, higher CA levels significantly reduced tensile strength and increased water solubility, whereas the tensile strength of films containing 1 mL CA did not differ significantly from that of the control (p > 0.05). These results demonstrate that the structural, physicochemical, and functional responses of Gel/KGM composite films varied with the nominal CA loading. Among the tested formulations, CA-3 represented a possible compromise between structural integrity and functional performance. Further studies using real food matrices are required to validate its practical applicability under actual food-packaging conditions.