Preparation and comparison of two functional nanoparticle-based bilayers reinforced with a κ-carrageenan-anthocyanin complex.

Abstract In the present study, two pH-sensitive bilayer films were developed and compared. Agar matrix incorporated with ZnO nanoparticles (NPs) or TiO2 NPs were combined with the infrastructure of a κ-carrageenan–Clitoria ternatea Linn anthocyanin (CA-CTLA) layer, denoted as AG-ZnO/CA-CTLA film and AG-TiO2/CA-CTLA film, respectively. The CA-CTLA layer was defined as the sensing layer, whereas the AG-TiO2 (or AG-ZnO) layer was the protective layer that enhanced the mechanical properties and colour stability. The AG-TiO2/CA-CTLA film displayed superior UV–vis light barrier property, pH sensitivity, and physical properties. The film's elongation at break and water vapour permeability were 57.08%, and 2.72 × 10−6 g.m−1.h−1.pa−1, respectively. Notably, the AG-TiO2/CA-CTLA film possessed the highest UV–vis light barrier properties, and the transmittance was close to 0 in the UV region. Furthermore, these films exhibited visual colour changes in the buffer solution (pH 2.0–12.0), ammonia vapour (80 M), and pork spoilage trials. Therefore, the bilayer films have promising properties for food packaging, especially the AG-TiO2 NPs/CA-CTLA film.