Mathematical modeling of carvacrol release from HD/PVA/starch-based active intelligent films

This study aimed to develop a hydrogel (HD)-based active intelligent packaging film for the controlled release of carvacrol (CA). HD was incorporated as a CA carrier within the matrix of acetylated distarch phosphate (ADSP) and polyvinyl alcohol (PVA). The structure and properties of HD and its effect on film properties were studied. Among them, the film containing 6 g HD (PRP-6 film) had the best overall performance. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction confirmed the good compatibility between HD and the film base. Thermogravimetric analysis revealed enhanced thermal stability of PRP-6 compared with that of the films with directly added CA (PCO film). The release kinetics of CA in PRP-6 films and PCO films was investigated under varying temperatures, humidity, and acid–base conditions. The PRP-6 film exhibited controlled CA release in response to environmental changes, extending the release period to 12 d compared with that of the PCO film. The first-order kinetic model provided the best fit for describing CA release behavior, and the release process of CA followed Fick's diffusion law. The PRP-6 film showed sustained antibacterial activity over a 12-day storage period. In addition, PRP-6 films retarded the increase in fish pH and L values and inhibited the decrease in fish TVB-N values. This study established a theoretical foundation for developing advanced active packaging systems in aquatic product preservation.