Effect of carvacrol on properties and release behavior of gelatin-egg white protein/polyethylene bilayer film

A bilayer antibacterial film of gelatin (G)-egg white protein (EW) containing carvacrol (CA) on polyethylene (PE) was prepared. This study investigated the effects of different concentrations of CA on the apparent viscosity and particle size of gelatin and egg white protein composite film-forming solution (FFS). The static rheological results showed that the viscosity of FFS increased significantly in the presence of CA. The results of particle size showed that FFS had good stability. Fourier transform infrared (FTIR) spectroscopy indicated that there were hydrogen bond interactions among G/EW and CA with good compatibility. Scanning electron microscopy (SEM) indicated that the incorporation of CA made the film surface structure denser. The film with CA had good antioxidant and antibacterial activities. Under the same conditions, the higher the CA content, the higher the release rate, and the release rate was positively correlated with the increase in temperature and ethanol content in the food simulant, which indicated that the bilayer antibacterial film containing CA could be used for packaging high-fat foods. Therefore, the G/EW-PE bilayer antibacterial film containing CA could make up for the poor water resistance of the edible monolayer film, and gave the antibacterial function that the polyethylene packaging film did not have. Practical Applications CA has safe and efficient antibacterial activity. It is listed by the Food and Drug Administration (FDA) in the list of additives that can be directly added to food for human consumption. Compared with the traditional single-layer packaging film (plastic film and edible packaging film), the G/EW-PE bilayer film containing CA can not only make up for the poor water resistance of the edible single-layer film, but also give the plastic film new packaging performance. This study characterized the microstructure, physical properties, antibacterial properties and the release of CA in the film, which provided theoretical reference for the development of food packaging.