## 3 Results and Discussion
### Antioxidant and Radical Scavenging Activities of Full-Fat Cow, Coat and Eve Yogurts
Protein and total sulfhydryl groups content of the three yogurt pHAP extracts are consistent with their antioxidant and scavenging capacities reported above as it is known that yogurt peptides exhibit antioxidant activities while the -SH group can be oxidized to -S-S-, which also contributes to the antioxidant potential of the product. [PERSON] & [PERSON] (2011) came to a similar conclusion, by observing that the antioxidant potential of the water-soluble extracts of traditional and commercial yogurts was proportional to their bioactive peptide content [11]. In a study of [PERSON] et al. (2017), the increase of \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Yogurt**} & **Lowry Assay** & **Bradford Assay** & **Total Sulfhydryl Groups** \\  & **(mg BSA/kg Yogurt)** & **(mg BSA/kg Yogurt)** & **(mg Glutathione/kg Yogurt)** \\ \hline Cow & 1237 \({}^{\mathrm{a}}\) \(\pm\) 22 & 2027 \({}^{\mathrm{a}}\) \(\pm\) 41 & 4.0 \({}^{\mathrm{a}}\) \(\pm\) 0.3 \\ Goat & 1214 \({}^{\mathrm{a}}\) \(\pm\) 17 & 1986 \({}^{\mathrm{a}}\) \(\pm\) 59 & 3.8 \({}^{\mathrm{a}}\) \(\pm\) 0.3 \\ Ewe & 1307 \({}^{\mathrm{b}}\) \(\pm\) 12 & 2247 \({}^{\mathrm{b}}\) \(\pm\) 45 & 5.2 \({}^{\mathrm{b}}\) \(\pm\) 0.2 \\ \hline \hline \end{tabular} \({}^{\mathrm{I}}\) Each value was expressed as mean \(\pm\) standard deviation of three replicates. Different lowercase letters in the same column represent significant differences in values (\(p<0.05\)) between cow, goat and ewe yogurts.  
\end{table} 
Table 6: Protein and total sulfhydryl groups content of cow, goat and ewe yogurt preparations obtained by pH adjustment and precipitation (pHAP) procedure \({}^{\mathrm{I}}\). \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Yogurt**} & \multicolumn{2}{c}{**Hydroxyl Radicals**} & \multicolumn{2}{c}{**Superoxide Radicals**} \\  & **(mg Trolox/kg Yogurt)** & **(mg Trolox/kg Yogurt)** \\ \cline{2-4}  & **pHAP Extract** & **CR Preparation** & **pHAP Extract** & **CR Preparation** \\ \hline Cow & 35.5 \({}^{\mathrm{a}}\)\(\pm\) 2.7 & 102.6 \({}^{\mathrm{a}}\)\(\pm\) 8.0 & 142.6 \({}^{\mathrm{a}}\)\(\pm\) 6.9 & 255.1 \({}^{\mathrm{a}}\)\(\pm\) 35.2 \\ Goat & 33.2 \({}^{\mathrm{a}}\)\(\pm\) 1.5 & 96.1 \({}^{\mathrm{a}}\)\(\pm\) 4.6 & 137.8 \({}^{\mathrm{a}}\)\(\pm\) 5.2 & 215.4 \({}^{\mathrm{a}}\)\(\pm\) 15.6 \\ Ewe & 50.2 \({}^{\mathrm{b}}\)\(\pm\) 1.8 & 133.1 \({}^{\mathrm{b}}\)\(\pm\) 7.3 & 171.5 \({}^{\mathrm{b}}\)\(\pm\) 2.0 & 377.7 \({}^{\mathrm{b}}\)\(\pm\) 17.4 \\ \hline \hline \end{tabular} \({}^{\mathrm{I}}\) Each value was expressed as mean \(\pm\) standard deviation of three replicates. Different lowercase letters in the same column represent significant differences in values (\(p<0.05\)) between cow, goat and ewe yogurts. Different capital letters in the same row represent significant differences in values (\(p<0.05\)) between pHAP and CR preparations of the same yogurt.  
\end{table} 
Table 5: Hydroxyl and superoxide anion radical scavenging activities of cow, goat and ewe yogurt preparations obtained by pH adjustment and precipitation (pHAP) and “Clarifying Reagent” (CR) \({}^{\mathrm{I}}\). the antioxidant and scavenging of ROS activities of yogurts during long-term storage was associated with the release of bioactive peptides through protein hydrolysis. The authors characterized the peptides as \"sacrificial\" antioxidants due to their ability to act quickly against the ROS [25]. Apart from peptides/proteins, the antioxidant activity of yogurts has been also related to the presence of lipids (e.g., linoleic acid), which seem to contribute to the anti-thrombotic and cholesterol-lowering properties of the product [26, 27]. The latter strengthens our findings as significantly higher antioxidant activities were recorded via the use of CR (dissolves both proteins and fats) than the water-soluble extracts obtained by pHAP and UC procedures.