**5. Conclusions**

In this study, we applied a new fumigation method by placing the essential oil on the sterile gauze inside the polymeric films. Fruit samples without PD and in open net packages were considered as controls and all packages were stored at 12 ± 1 ◦C for 18 days. In combination with plant extract (PD), polymeric films played a very effective role in the quality maintenance of longan fruit samples. Compared to control packages, all types of polymeric films in combination with PD prevented weight loss, inhibited microbial growth, and delayed the pericarp browning of longan fruit samples. PD-treated fruit samples and sealed in packaging films also exhibited high firmness and color values, better prevented the oxidation of the phenols and flavonoids, and better inhibited enzyme activity than the control treatment. Extended shelf life of 18 days was observed in OPP-20 and OPP-40 packaging films with good quality attributes. SEM analysis showed a clear uniformity in the pericarp structures, which was entirely associated with the obtained results. Overall, PD maintained the structural integrity of the pericarp, prevented pericarp browning, inhibited the growth of microorganisms, and had a very positive effect on longan fruit quality as compared to control fruit samples. Therefore, with a combination of OPP-20 and OPP-40 polymeric films, PD could be applied commercially as a potent antioxidant and antimicrobial agent in a wide range of food products to replace synthetic fumigants or preservatives.

**Author Contributions:** Conceptualization and design, C.H. and M.R.K.; methodology, M.R.K.; resources, H.S. and L.R.; software, R.U., H.U., H.S., M.A. and A.K.; writing—original draft, M.R.K.; supervision, C.H.; statistical analysis, M.R.K. and I.M.Q.; data curation, M.R.K., H.U., T.N., M.A. and A.K.; writing—review and editing, M.R.K., C.H., I.M.Q. and R.U.; funding acquisition, C.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Guangxi Science and Technology Plan Project (Project No. AB18221126), the Guangxi Natural Science Foundation Program (2019JJD120012), and the Postdoctoral Project of the Guangxi University.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors thank Guangxi University for providing a Postdoctoral Fellowship.

**Conflicts of Interest:** The authors declare no conflict of interest.
