## 3 Results and Discussion
### 3.2. _Nutritional Characteristics of Functional Bread_
#### 3.2.8 Antioxidant Activity  
After assessing the antioxidant activity of the bread samples (as depicted in Figure 6), it was observed that all samples incorporated with sea buckthorn pomace powder exhibited elevated values for this parameter (over 200 QE/100 g product) in comparison to the control sample. This augmentation is attributed to the presence of polyphenols, such as phenolic acid and flavonoids, which are acknowledged as the most active components responsible for the antioxidant characteristics of various sea buckthorn varieties. In addition to polyphenols, the antioxidant ability of sea buckthorn is linked to the combined influence of ascorbic acid and carotenoids [36]. Based on the obtained results, it can be concluded that the addition of sea buckthorn pomace powder led to a significant (\(p<0.05\)) escalation in the antioxidant activity of the developed products. The C10 bread sample had the highest value, whereas the M10 sample had the lowest value. Similar results were obtained by [PERSON] et al., 2021 [36]; namely, when the percentage of sea buckthorn was increased to 20% in cereal biscuits, a noticeable decrease in antioxidant activity was observed. This decline may be due to some antioxidants that can act as prooxidants at higher concentrations [36]. The antioxidant analysis of the bread samples confirmed that the products exhibit substantial antioxidant potential and constitute a rich source of antioxidant compounds, which may impart many beneficial effects on the human body.  
[PERSON] et al., 2016 [17] reported that the presence of antioxidants in bread samples with sea buckthorn reduces the degree of lipid oxidation due to the fat content of sea buckthorn. Additionally, [PERSON] et al., 2021 [36] found that cereal biscuits with 15% sea buckthorn biomass had increased antioxidant activity.  
According to the study conducted by [PERSON] et al., 2016 [17], the antioxidant activity (expressed as the percentage of free inhibited DPPH radicals) of pastry products increased from \(-18.08\pm 1.21\%\) to \(73.52\pm 0.63\%\) for 4% sea buckthorn flour gingerbread, and from \(-12.98\pm 0.91\%\) to \(17.86\pm 0.61\%\) for 4% sea buckthorn flour sponge cake. On the other hand,  
Figure 6: Antioxidant activity of functional bread samples with the addition of sea buckthorn pomace powder. Means followed by a common letter are not significantly different (\(p>0.05\)). Values followed by different superscript letters in the same column are significantly different (\(p<0.05\)). Means that do not share a letter in a column are significantly different (\(p<0.05\)).  
[PERSON] et al., 2020 [29] demonstrated that the addition of 1% sea buckthorn berry flour slightly increased the antioxidant activity of their samples, but it remained negative (\(-\)8.65 \(\pm\) 0.62%). When 5% sea buckthorn biomass flour was added, the antioxidant activity of the samples increased to 20.05 \(\pm\) 0.51%, which was significantly lower than the antioxidant activity observed in the study conducted by [PERSON] et al., 2016 [17].  
[PERSON] et al., 2019 [30] showed that the antioxidant activity of sea buckthorn powder used in biscuit preparation was affected by the drying temperature. Specifically, biscuits made with sea buckthorn powder dried at 50 \({}^{\circ}\)C for 12 h exhibited an antioxidant activity of 88.97 \(\pm\) 0.82, while those made with powder dried at 80 \({}^{\circ}\)C for 5 h had an activity of 89.14 \(\pm\) 0.27.  
In a separate study by [PERSON] and [PERSON], 2018 [27], it was observed that the type and amount of sea buckthorn powder used in bakery products influenced their antioxidant activity. Bakery products made with sea buckthorn peel powder had the highest antioxidant activity, followed by those made with marc powder and seed powder. This was due to the peel powder's high content of ascorbic acid, total phenolic content, and total flavonoid content, followed by the marc powder and seed powder.