## 3 Results and Discussion  
### Physico-Chemical Properties of Oils  
The total carotenoid content of the control oil and of the oils macerated with dried tomato by-products is presented in Table 1. No carotenoids were detected in the refined sunflower oil, but maceration of the oil with tomato by-products determined the enrichment of the oil in carotenoids. Moreover, a linear dependency was found between the content of carotenoids in the enriched oils and the amount of extracted by-products (r = 0.996).  
Generally, sunflower oil shows a lower oxidation resistance compared to other edible oils due to the higher unsaturation degree and the lower antioxidant protection conferred by alpha-tocopherol as compared with other tocopherols (gamma- and delta-tocopherol) with higher antioxidant potency that are found in other edible oils (i.e., soybean oil) [33]. Significant decreases in the peroxide value were recorded in the oils after the extraction of 2.5% and 5% dried tomato by-products compared with the control oil, which could be ascribed to the antioxidant action of the carotenoids and of the other antioxidant compounds extracted from dried tomato by-products.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline  & **C** & **DTB2.5** & **DTB5** \\ \hline Total carotenoid content (mg/kg) & nd a & 19.48 \(\pm\) 0.68 b & 34.86 \(\pm\) 0.85 c \\ Acid value (g/kg) & 0.56 \(\pm\) 0.03 a & 0.84 \(\pm\) 0.05 b & 0.98 \(\pm\) 0.04 c \\ Peroxide value (meq/kg) & 2.10 \(\pm\) 0.10 c & 1.88 \(\pm\) 0.09 b & 1.42 \(\pm\) 0.06 a \\ Antioxidant activity (mmol/kg) & 2.78 \(\pm\) 0.13 a & 3.34 \(\pm\) 0.17 b & 4.01 \(\pm\) 0.18 c \\ L* & 78.85 \(\pm\) 0.25 c & 76.92 \(\pm\) 0.28 b & 75.7 \(\pm\) 0.32 a \\ a* & 0.12 \(\pm\) 0.03 a & 0.65 \(\pm\) 0.03 b & 0.95 \(\pm\) 0.04 c \\ b* & 6.37 \(\pm\) 0.21 a & 4.69 \(\pm\) 0.28 b & 3.61 \(\pm\) 0.46 c \\ \hline \hline \end{tabular}
\end{table}
Table 1: Acid values, peroxide values, total carotenoid content, and antioxidant activity of control and experimental oils.  
The extraction of dry tomato by-products resulted in a significant increase (\(p<0.05\)) of the radical scavenger activity as a result of the extraction of carotenoids and other antioxidant compounds. The antioxidant activity was linearly correlated with the carotenoid content of the oils (r = 0.992). DTB extraction determined a slight but significant (\(p<0.05\)) increase in the acid value of the oils. This may be assigned to the hydrolysis of triglycerides as a result of the action of lipolytic enzymes originating from the tomato by-product.  
The level of the CIELab parameters of the control and extracted oils are shown in Table 1. The extraction of dry tomato by-products significantly influenced the color values of the oils (\(p<0.05\)). Redness (a* values) increased while lightness (L* values) and yellowness (b* values) decreased, changes that could be assigned to the extraction of carotenoids, especially the red lycopene, in the oil. A similar evolution of color parameters has been previously reported by [PERSON] et al. [27] in different oils enriched with carotenoids from dried tomato waste. However, [PERSON] et al. [34] reported an increase in all color values, including b* values in the oils enriched with carotenoids extracted from by-products of sea buckthorn. The differences may be due to the predominance of the red lycopene in the carotenoid profile of tomato waste [24], as compared with sea buckthorn by-products whose carotenoid profile is dominated by the yellow zeaxanthin and the orange \(\beta\)-carotene pigments [35; 36].