Abstract: In order to further develop the application of plant essential oil on post-harvest sterilization and preservation of fruits and vegetables, the oregano essential oil was used as the core material, and gelatin and gum arabic as the wall material to prepare oregano essential oil microcapsules (OEO-MPs) by the coacervation method through the optimized process. Then, its physicochemical and slow-released properties were further characterized using scanning electron microscope, fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Finally, the anti-fungal activity of OEO-MPs and their effects on decay rate and disease resistance related enzyme activities in shelf life of apricot fruit were evaluated at different application dose. The results showed that the optimal process conditions were that the core-to-wall ratio was 1:1, the wall material concentration was 1%, the reaction temperature was 45 ℃, and the reaction time was 30 min, and the microencapsulation rate of OEO-MPs prepared by this process was 83.65%, the loading amount of oregano essential oil (OEO) was 74.36%, and the particle size was 147 μm. Compared to single oregano essential oil (98% purity), OEO-MPs maintained higher stability, and obtained better spherical and regular surface structure, higher thermal stability and slow-released performance. In addition, 4% of OEO-MPs reduced the total number of colonies, molds and decay rate of apricot fruit during shelf life and increased peroxidase, L-phenylalanine ammonia-lyase, β-1, 3-glucanase, catalase and chitinase activity, while reduced the polyphenol oxidase activity during apricots shelf life than that in control. These results provided a new idea for the development of a slow-released bacteriostatic agent based on plant essential oils.

Key words: Oregano essential oil, Microcapsules, Slow-released, Fungicides