## 3 Results and Discussion
### Color Characteristics of Yogurt Samples  
Color is an important quality factor of yogurt, which affects the acceptance of the product by the consumer. The presence of milk fat globules and casein micelles, which can scatter light in the visible spectrum [41], is responsible for the white color of yogurt. The addition of plant extracts provokes changes in yogurt samples and influences consumer choices. In Table 2, color parameters L*, a*, b*, chroma, and hue of all samples were presented one day after the fermentation and storage at 4 \({}^{\circ}\)C.  
Yogurt with 0% \(w\)/\(w\) lyophilized sea buckthorn extract had the lowest a* value of around \(-\)1.92 \(\pm\) 0.02 and the lowest b* value of about 10.2 \(\pm\) 0.57, (\(p\) < 0.05). With the addition of extracts of LSB to the samples, the a* and b* values increased while the L* values fluctuated according to the increase in LSB extract concentrations. However, the samples containing extracts of LSB at a concentration of 2% and 3% \(w\)/\(w\) presented a higher L* value than the rest of the extract concentrations and the control with values of 82.26 \(\pm\) 1.41 and 81.88 \(\pm\) 0.79, respectively (\(p\) > 0.05). The more the concentration of extract of LSB increased to 0.5%, 1%, 2%, and 3% \(w\)/\(w\), the more the values of a* and b* increased. More specifically, yogurt with 3% \(w\)/\(w\) lyophilized sea buckthorn, which was the highest concentration added, had the highest a* and b* values of 12.5 \(\pm\) 0.27 and 57.1 \(\pm\) 0.90, respectively. These samples have more redness and yellowness due to the yellow-orange color of the sea buckthorn and samples with a higher proportion of sea buckthorn extract had a more intense yellow and red color compared to the control sample. The high content of carotenoids in sea buckthorn is undoubtedly responsible for the yellow color. Hue and chroma measurements were also affected by the addition of different concentrations of extracts of LSB. In general, the color of extracts of LSB is responsible for color measurements on the enriched yogurts. For the concentrations of 0.5% and 1% \(w\)/\(w\) extracts of LSB, an increase in the b* values compared to control samples and a decrease in their L* values (74.85 \(\pm\) 0.71 and 74.95 \(\pm\) 0.23) was noticed, which is due to phenolic degradation and the formation of more brown pigments. Similar results were found in the yogurt samples fortified with extracts of argel leaf [15], chia seed extract [42], and _Pleurotous o \begin{table}
\begin{tabular}{c c c c c c} \hline
**Lyophilized Sea** & & & & & \\
**Buckthorn Extract** & **L*** & **a*** & **b*** & **Chroma*** & **Hue Angle (h*)** \\
**(\% \(w\)/\(w\))** & & & & & \\ \hline
0 & 78.99 \(\pm\) 2.37 \({}^{\circ}\) & \(-\)1.92 \(\pm\) 0.02 \({}^{\mathrm{d}}\) & 10.26 \(\pm\) 0.57 \({}^{\mathrm{e}}\) & 10.44 \(\pm\) 0.56 \({}^{\mathrm{e}}\) & 178.61 \(\pm\) 0.01 \({}^{\mathrm{a}}\) \\
0.5 & 74.85 \(\pm\) 0.71 \({}^{\mathrm{b}}\) & 1.25 \(\pm\) 0.18 \({}^{\mathrm{c}}\) & 16.32 \(\pm\) 0.21 \({}^{\mathrm{d}}\) & 16.37 \(\pm\) 0.20 \({}^{\mathrm{d}}\) & 1.49 \(\pm\) 0.01 \({}^{\mathrm{b}}\) \\
1 & 74.95 \(\pm\) 0.23 \({}^{\mathrm{b}}\) & 1.28 \(\pm\) 0.10 \({}^{\mathrm{c}}\) & 17.84 \(\pm\) 0.18 \({}^{\mathrm{c}}\) & 17.88 \(\pm\) 0.18 \({}^{\mathrm{c}}\) & 1.50 \(\pm\) 0.01 \({}^{\mathrm{b}}\) \\
2 & 82.26 \(\pm\) 1.41 \({}^{\mathrm{a}}\) & 6.33 \(\pm\) 0.20 \({}^{\mathrm{b}}\) & 30.37 \(\pm\) 0.49 \({}^{\mathrm{b}}\) & 31.03 \(\pm\) 0.47 \({}^{\mathrm{b}}\) & 1.37 \(\pm\) 0.01 \({}^{\mathrm{c}}\) \\
3 & 81.88 \(\pm\) 0.79 \({}^{\mathrm{a}}\) & 12.57 \(\pm\) 0.27 \({}^{\mathrm{a}}\) & 56.19 \(\pm\) 0.90 \({}^{\mathrm{a}}\) & 57.58 \(\pm\) 0.82 \({}^{\mathrm{a}}\) & 1.35 \(\pm\) 0.01 \({}^{\mathrm{c}}\) \\ \hline \end{tabular}  
* Different letters within the columns indicate significant differences (\(p\) < 0.05) among the different treatments. All measurements were conducted in triplicate.  
\end{table}