Turmeric and Red Cabbage Extract Composites with Chitosan as Natural Ingredient-Based pH-Responsive Intelligent Packaging Strips

Abstract

The successful fabrication and testing of two different intelligent packaging strips based on cross-linked chitosan composites containing (i) curcumin and (ii) red cabbage anthocyanins is reported. The intelligent strips were analyzed using selected analytical techniques, including Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), and UV–visible spectroscopy (UV–vis). The tensile strength of the materials was evaluated, determining values for curcumin-containing films (CVGCurc) and anthocyanin-containing films (CVGRCE) of 9.5 and 9.9 MPa, respectively. The surface water contact angles were determined as 84.7 ± 3° and 56.5 ± 5° for CVGCurc and CVGRCE films. Furthermore, both intelligent film strips demonstrated strong UV-blocking capacities and good barrier properties to water vapor, determined as 2.6 × 10^–10 ± 0.6 × 10^–11 g·m^–1·s^–1·Pa^–1 and 3.65 × 10^–10 ± 0.8 × 10^–11, g·m^–1·s^–1·Pa^–1 for CVGCurc and CVGRCE films, respectively. Overall, the physiochemical properties determined show promising values for both films for application as intelligent packaging strips, with CVGCurc displaying improved performance in mechanical, barrier, and thermal investigations. Finally, the film strips were applied to a prawn degradation study, evaluating the pH-triggered color change over time. Both films displayed a significant color change with an increase in pH within the packaging headspace, with CVGRCE films showing the largest ΔE value (47.9). Therefore, these two intelligent films offer a proof-of-concept study for the application of cross-linked chitosan films to intelligent packaging. Indeed, the films can be considered a promising starting point for the development and commercialization of simple, green, and cost-effective smart packaging materials to aid consumers in an effort to minimize household food waste.