Development of Ultrasound-Assisted Doped with White Round Grapefruit Essential Oil Bilayer Films for Lycium barbarum Preservation

The present study explored assisted treatments with different ultrasonic times (0, 5, 10, 15, and 20 min) to evaluate the combined effect of three composite films (cedarwood essential oil, grapefruit essential oil, and white round grapefruit essential oil) on the preservation of goji berries. The results showed that ultrasound-assisted treatment for 10 min significantly improved the mechanical and barrier properties of chitosan/poly(vinyl alcohol) films. According to this experiment, the preservation effect of the three composite films on Lycium barbarum was compared by the layer-by-layer self-assembly method, and the results showed that chitosan/poly(vinyl alcohol) film/white round grapefruit essential oil had a strong antimicrobial effect on Aspergillus niger. In addition, the ultrasonic-assisted bilayer film (zein-chitosan/poly(vinyl alcohol)/white round grapefruit essential oil) could effectively reduce the weight loss rate, decay rate, and malondialdehyde content of L. barbarum at 4 and 25 °C and thus prolong the shelf life. In conclusion, the newly developed zein-chitosan/poly(vinyl alcohol) bilayer film with white round grapefruit essential oil can be an effective alternative to inedible polymers as a sustainable food packaging solution in food packaging materials.