## 3 Results and Discussion
### Antioxidant and Radical Scavenging Activities of Cow Yogurts with Different Fat Content
\begin{table}
\begin{tabular}{c c c c c c} \hline \multirow{2}{*}{**\% Fat of Yogurt**} & \multicolumn{2}{c}{**FRAP Assay**} & \multicolumn{2}{c}{**FRAP Assay**} \\  & **(mg/L Trolox per kg Yogurt)** & **(mg/L Gallic Acid per kg Yogurt)** \\ \cline{2-5}  & **pHAP Extract** & **UC Extract** & **CR Preparation** & **pHAP Extract** & **UC Extract** \\ \hline
0 & 41.0 \({}^{\text{a}\text{A}}\)\(\pm\) 1.1 & 57.0 \({}^{\text{a}\text{B}}\)\(\pm\) 1.3 & 172.8 \({}^{\text{a}\text{C}}\)\(\pm\) 2.9 & 48.1 \({}^{\text{a}\text{A}}\)\(\pm\) 1.3 & 66.9 \({}^{\text{a}\text{B}}\)\(\pm\) 1.6 \\
2 & 36.4 \({}^{\text{b}\text{A}}\)\(\pm\) 1.3 & 51.0 \({}^{\text{b}\text{B}}\)\(\pm\) 1.4 & 152.1 \({}^{\text{b}\text{C}}\)\(\pm\) 3.0 & 42.7 \({}^{\text{b}\text{A}}\)\(\pm\) 1.5 & 59.8 \({}^{\text{b}\text{B}}\)\(\pm\) 1.6 \\
4 & 32.2 \({}^{\text{c}\text{A}}\)\(\pm\) 1.2 & 45.6 \({}^{\text{c}\text{B}}\)\(\pm\) 1.6 & 123.8 \({}^{\text{c}\text{C}}\)\(\pm\) 5.7 & 37.8 \({}^{\text{c}\text{A}}\)\(\pm\) 1.4 & 53.5 \({}^{\text{c}\text{B}}\)\(\pm\) 1.9 \\ \hline \end{tabular}  
* 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 yogurts with different fat content. Different capital letters in the same row represent significant differences in values (\(p<0.05\)) between pHAP, UC and CR preparations of the same yogurt.  
\end{table} 
Table 8: Antioxidant activities of cow yogurts with different fat content preparations obtained by pH adjustment and precipitation (pHAP), ultra-centrifugation (UC), and “Clarifying Reagent” (CR), as determined by FRAP assay \({}^{1}\). incubation and precipitation) that potential lead to antioxidants degradation or loss.CR preparations of cow yogurts with different fat content were also tested using the FRAP assay (Table 8). Again, yogurt with 0% fat appeared to be the most active one, followed by yogurt with 2% fat and that with 4% fat. Scavenging capacities of cow yogurt with different fat content against hydroxyl radicals and superoxide anion are presented in Table 9. In these assays, pHAP extracts and CR preparations of the yogurts were used. Scavenging capacities of both pHAP and CR yogurt preparations against ROS followed the order 0% > 2% > 4% fat content. Cow yogurt with less fat content in pHAP and UC extracts exhibited higher antioxidant and scavenging of ROS activities than cow yogurt with higher fat content. To sum up, all the antioxidant assays tested indicate that the water-soluble constituents of cow yogurt with less fat content have higher antioxidant and scavenging of ROS activities than cow yogurt with higher fat content. A similar pattern was followed in CR preparations, as the cow yogurt with 0% fat content showed the highest antioxidant and scavenging of ROS potential than the other cow yogurts. This finding indicates that proteinaceous and water-soluble constituents of cow yogurt demonstrate higher antioxidant potential than the lipids. From another point of view, it was confirmed again (as in Section 3.1) the considerably stronger antioxidant and ROS scavenging activities observed in the CR yogurt preparations as compared with the pHAP and UC extracts. This is attributed to the aqueous nature of the extracts, which do not contain any lipids and have a low protein content. On the other hand, \"Clarifying Reagent\" dissolves both proteins and fat, indicating that the detected activities might be related to the significant presence of these compound categories. Considering also that the yogurt with less fat content contains higher protein and water-soluble constituents than the respective ones with higher fat content (fat removal leads to the increase of protein and soluble constituents), the yogurt antioxidant activities are mainly attributed to their peptide/protein content.