## 4 Discussion
A comparable study examined the fortification of refined olive oil with olive leaves, using conventional maceration for 5 days, and the phenolic content was significantly improved in the final fortified product [30]. Moreover, similar results were obtained in the study of [PERSON] et al. [38], which utilized dry lemon in various concentrations to enrich olive oil (virgin (VOO) and refined olive oil (ROO)) by conventional maceration for a 2-month duration at room temperature. In contrast, [PERSON] et al. [39] observed a decreased phenolic capacity when utilizing dry lemon zest instead of dried lemon at 5% concentration for 15 days duration at room temperature. This result of conventional maceration does not confirm our findings regarding lemon peel but this may be expected due to variations between different cultivars of the samples. Furthermore, similar results were presented by [PERSON] et al. [40], who performed a conventional maceration of 10 days' duration to enrich olive oil with fresh instead of dried orange peel in the same concentration of 5%\(w/w\). In the case of the conventional maceration methods for oil fortification with bioactive compounds from herbs, there is a large field of research on extra virgin and virgin olive oil, while research on refined olive oil is limited [41]. [PERSON] et al., [42], [PERSON] et al., [39], and [PERSON] et al. [43] performed a conventional maceration on virgin olive oil by enriching it with a 5% dry sample for a duration of 10 and 15 days. The first observed an increase in the total antioxidant activity of the enriched olive oil, while the second observed a decrease in the phenolic capacity. Moreover, [PERSON] et al. [39] used 5% and 15%\(w/w\) concentration of dry basil to enrich EVOO by conventional maceration at room temperature for 15 days with no phenolic increase in both concentrations. The results of the present study illustrated that refined olive oil fortification with 8% and 17% of dry basil resulted in an increased phenolic content in both the 15 and 30 day period during conventional maceration [39]. Regarding the incubator shaking maceration, there are not many studies that followed the same methodology for olive oil fortification with herbs or by-products. In the present study, it was presented that the phenolic content of most fortified refined oils with herbs and by-products was increased, while basil, sage, dittany, pomace, olive leaves, orange, and mandarin peel showed significant antioxidant capacity levels in all concentrations and times of extraction. According to literature data, [PERSON] et al. [44] performed a similar shaking process to fortify virgin olive oil with oregano and the findings towards phenolic content agree with our findings when performing the incubator maceration method derived with our findings. Therefore, this method has promising results that may benefit from more research on fortifying olive oils using an incubator-assisted maceration. In addition, the present study examined the ultrasound-assisted extraction maceration by using different times, temperatures, and concentrations of the herbs and by-products, presenting significant results towards antioxidant capacity and polyphenic content to the refined olive oil. Different temperatures (30 \({}^{\circ}\)C/40 \({}^{\circ}\)C) and concentrations (5% \(w/w\) and 10% \(w/w\)) of the sample during the extraction process did not play an important role in enriching the antioxidant capacity of the refined oil. As for the phenolic content of fortified refined oil, there are some noticeable results. Lemon balm, St. John's wort, and mandarin peel presented lower values during the ultrasound-assisted maceration process. This resulted because ultrasonic power plays an important role in phenolic degradation along with temperature conditions. The low observation of the total phenolic content of the above-mentioned samples is in line with the results of similar studies [45; 46].