Abstract: In order to further develop the application of plant essential oil in post-harvest sanitation and preservation of fruits and vegetables, oregano essential oil was microencapsulated by the coacervation method using gelatin and arabic gum as the wall material under optimized conditions. The physicochemical and slow-release properties of oregano essential oil microcapsules (OEO-MPs) were characterized using scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Finally, the anti-fungal activity of different doses of OEO-MPs on apricot fruit during postharvest storage and its effects on decay incidence and disease resistance-related enzyme activities were evaluated. The results showed that the optimal process conditions were as follows: core-to-wall ratio 1:1, wall material mass ratio (gelatin and gum arabic) 1:1, reaction temperature 45 ℃, and reaction time 30 min. The microencapsulation rate of OEO-MPs prepared by the optimized process was 83.65%, the loading amount of oregano essential oil (OEO) was 74.36%, and the particle size was 147 μm. Compared with oregano essential oil (98% purity), OEO-MPs, spherical with a more regular surface structure, exhibited higher stability, and possessed higher thermal stability and slow-release performance. In addition, 4% OEO-MPs reduced the total number of colonies, total mold count and decay incidence of apricot fruit during shelf life, increased peroxidase, L-phenylalanine ammonia-lyase, β-1,3-glucanase, catalase and chitinase activities, and reduced polyphenol oxidase activity compared with the control. These results provided a new idea for the development of a slow-release bacteriostatic agent based on plant essential oil.

Key words: oregano essential oil; microcapsules; slow-release; anti-fungal agent