## 4 Conclusions  
The present findings indicate that ultrasound-assisted maceration of VAO with powders of avocado leaves (AL) or olive processing by-products (OL and OP) may increase its content in various bioactives, mainly of lipophilic nature, in a dose-dependent manner. Regardless of the fortification agent used, the oxidative stability and antioxidant potential improved, while standard quality parameters remained within the typical ranges for VAOs. Although the oxidative stability correlated significantly with the total polar phenol content, further insight is required to better understand such findings considering that the HPLC analysis indicated low enrichment in strong phenolic antioxidants. Color alteration, especially in the case of AL-VAOs, may not necessarily be an issue for acceptability considering the literature findings for commercially available samples. The analysis of the VOCs indicated some possible safety and sensory issues. The presence of estragole and methyl-eugenol in the AL-VAOs or odorants in OP-VAOs and OL-VAOs, with potential unpleasant contributions, must not be overlooked in future studies. In the same direction, further research on the handling practices of raw materials to reduce off-flavors may be beneficial for oil manufacturers.  
**Supplementary Materials:** The following supporting information can be downloaded at [[https://www.mdpi.com/article/10.3390/foods14020294/s1](https://www.mdpi.com/article/10.3390/foods14020294/s1)]([https://www.mdpi.com/article/10.3390/foods14020294/s1](https://www.mdpi.com/article/10.3390/foods14020294/s1)), Table S1: Quality characteristics and physicochemical composition of the control extra virgin olive oil sample; Table S2: Fatty acid profile and oxidative susceptibility of control and enriched oil samples; Table S3: Color parameters of the studied control and enriched virgin avocado oils; Table S4: Volatile compounds of the control and enriched virgin avocado oils; Figure S1: High-resolution mass spectrum of avocado leaf extract; Figure S2: ATR-FT-IR spectra of the studied control and enriched virgin avocado oils; Figure S3: Scattered t1/t2 score plots of the studied control and enriched virgin avocado oils; Figure S4: HPLC-DAD chromatograms of the studied control and enriched virgin avocado oils. Figure S5: Pictures of the control and enriched virgin avocado oils. C-VAO = freshly extracted virgin avocado oil; AL5-AL10-AL20, OL5-OL10-OL20, and OP5-OP10-OP20 represent C-VAO enriched with avocado leaves, olive leaves, and olive pomace, respectively, at 5, 10, and 20% (_w/w_) employing ultrasound-assisted maceration.  
**Author Contributions:** Conceptualization, S.A.O. and N.N.; methodology, I.P., S.S., S.A.O., S.L. and N.N.; formal analysis, I.P., S.S. and S.L.; investigation, I.P., S.S., S.A.O. and N.N.; writing--original draft preparation, I.P.; writing--review and editing, I.P., S.A.O. and N.N.; visualization, I.P. and S.S.; supervision, N.N. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.  
**Acknowledgments:** We would like to thank the Institute of Olive, Subtropical Plants, and Vine (Chania, Crete, Greece) for the collection and shipping of the avocado leaves; the Union of Agricultural Cooperative of Lakonia (Lakonia, Greece) for the shipping of the dried olive pomace samples; and the Evercrete-Antonakis Bros company (Chania, Greece) for the donation of the reference avocado oil sample.  
**Conflicts of Interest:** The authors declare no conflicts of interest.