Design of pH-sensitive sodium alginate/polyvinyl alcohol films with myricetin nanocrystals for intelligent food packaging.

Abstract

With the growing consumer demand for fresh and safe foods, intelligent packaging materials that monitor food quality in real time have attracted significant attention. Here, we report a pH-sensitive sodium alginate/polyvinyl alcohol/myricetin nanocrystals (SPMH) film as multifunctional intelligent food packaging. The prepared film showed satisfactory film-forming ability, biodegradability, and mechanical properties (83.62 MPa). Moreover, SPM-H film exhibited excellent water vapor barrier and oxygen barrier properties, reaching 7.4 × 10-11 g·m·m-2·Pa-1·s-1 and 242.51 cm3/m2 d 0.1 MPa, respectively. Notably, the incorporation of water-soluble myricetin nanocrystals (MNC), obtained via anti-solvent crystallization, imparted superior and multifunctional properties that go beyond conventional natural pigments. The SPM-H film exhibited imparted remarkable antibacterial, antioxidant, and UV shielding properties, thereby extending food shelf life by one day compared to conventional polyethylene (PE) packaging. Most importantly, the MNC endowed the film with a distinct dual-mode (colorimetric/fluorescence) pH-responsive behavior, a feature rarely achieved by most natural pigments, which significantly enhances the reliability of spoilage monitoring. These findings emphasize the potential of SPM-H films as sustainable, multifunctional intelligent food packaging for food preservation and safety monitoring.