Characterization of thyme essential oil composite film based on soy protein isolate and its application in the preservation of cherry tomatoes

Soy protein isolate (SPI) can be used as a carrier for essential oils in active packaging with the purpose of inhibiting the growth of spoilage microorganisms on food and extending food storage time. This study assessed the effect of adding thyme essential oil (TEO) on the physical properties, antioxidant activity, and antibacterial properties of thyme essential oil films (TEOF) using SPI as the film-forming matrix. The results indicated that the property of the composite film is improved after adding TEO. Scanning electron microscopy (SEM), infrared spectroscopy and X-ray diffraction (XRD) were used to analyze the better compatibility of the film matrix. Antibacterial experiments showed that the addition of TEO resulted in a stronger inhibitory effect of the composite film on Staphylococcus aureus and Escherichia coli. Furthermore, the results of the cherry tomato packaging test demonstrated that the film with concentration of 2.4 g/100 g TEO had the best preservation effect during storage, which could delay the decay, providing a reference for its application in food packaging.