## 3 Results
### Method Application  
Two raw (unprocessed) milk samples from two ruminant species (cow and sheep) were divided in three sub-samples. From the milk samples considered, the fatty acid profile (Table 4) was determined at t\({}_{0}\) and the optimized TBARS method was applied: 5 mL of samples, 10 mL of 20% TCA, and 90 min incubation with TBA 0.8% at 80 \({}^{\circ}\)C, without adding antioxidant. Determinations were performed after defrosting of samples overnight in the refrigerator, at 4 \({}^{\circ}\)C (t\({}_{0}\)) and after keeping them for 24 h at 20 \({}^{\circ}\)C (t\({}_{1}\)). The results are presented in Table 5. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Fatty Acids g/100 g** & **Cow Milk** & **Sheep Milk** \\ \hline C4:0 & Butyric acid & 0.05 & 0.02 \\ C6:0 & Caprotic acid & 1.35 & 1.22 \\ C8:0 & Caprylic acid & 1.74 & 2.12 \\ C9:0 & Nonanoic acid & 0.14 & 0.39 \\ C10:0 & Capric acid & 5.04 & 9.22 \\ C11:0 & Undecanoic acid & 0.47 & 0.55 \\ C12:0 & Lauric acid & 6.57 & 7.40 \\ C13:0 & Tricdeanoic acid & 0.33 & 0.55 \\ C14:0 & Myristic acid & 14.80 & 15.82 \\ C15:0 & Pentadecanoic acid & 0.58 & 0.25 \\ C16:0 & Palmitic acid & 34.29 & 28.29 \\ C17:0 & Heptadecanoic acid & 0.46 & 0.71 \\ C18:0 & Stearic acid & 6.19 & 1.42 \\ C20:0 & Arachid acid & 0.04 & 0.18 \\ SFAs 1 & & 72.05 & 68.14 \\ C14:1 & Myristoleic acid & 1.63 & 1.08 \\ C15:1 & Pentadecenoic acid & 2.00 & 3.15 \\ C16:1 & Palmitoleic acid & 2.77 & 3.75 \\ C17:1 & Heptadecenoic acid & 0.58 & 0.61 \\ C18:1n9c & Oleic cis acid & 16.07 & 15.52 \\ MUFAs 2 & & 23.05 & 24.11 \\ C18:3n3 & Linolenic alfa acid & 0.21 & 0.44 \\ C20:3n3 & Eicosatrienoic acid & 0.08 & 0.07 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Fatty acid profiles for cow and sheep milk samples (\(n=3\)). It has to be highlighted that sheep milk presented higher PUFAs and MUFAs concentrations and lower saturated fatty acids (SFAs) concentration than cow milk samples. Moreover, it was observed that the \(\Omega_{3}\) and \(\Omega_{6}\) fatty acids had higher concentrations in sheep milk samples than in cow milk samples. As shown in Table 5, the absorbance values obtained for sheep milk were higher than those obtained for cow milk. After 24 h of storage at room temperature, there was even higher degradation in the case of sheep milk compared to cow milk for each degradation parameter considered (absorption wavelengths considered--450, 495, and 532 nm), as shown in Figure 2.  
In addition, it was observed that after 24 h of storage at room temperature, the degradation yield expressed for MDA concentration was higher in the case of sheep milk than for cow milk (13.40% and 8.07%, respectively). Data regarding the statistical correlation between fatty acids classes and lipids degradation parameters is presented in Table 6. The parameters considered for analysis were strongly positively correlated (Pearson correlation with 0.01 significance level) between each other except for the \(\Omega 6/\Omega 3\) ratio. Only SFAs values were strongly negatively correlated with all other parameters (except for the \(\Omega 6/\Omega 3\) ratio) proving an inverse proportionality between those classes of compounds and oxidation products. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fatty Acids g/100 g** & **Cow Milk** & **Sheep Milk** \\ \hline Omega 3  & 0.29 & 0.51 \\ C18:2n6t & Linoleic trans acid & 0.47 & 0.18 \\ C18:2n6c & Linoleic cis acid & 2.39 & 4.67 \\ C18:3n6 & Linolenic gamma acid & 0.09 & 0.00 \\ CLA (c9, t11) & Conjugate linoleic acid & 0.19 & 0.53 \\ C20:2n6 & Eicosadienoic acid & 0.04 & 0.08 \\ C20:3n6 & Eicosatrienoic acid & 0.00 & 0.12 \\ C20:4n6 & Arachidic acid & 0.18 & 0.23 \\ Omega 6 4  & 3.35 & 5.80 \\ PUFAs 5  & 3.64 & 6.31 \\ \hline \hline \end{tabular} \({}^{1}\)Saturated fatty acids, \({}^{2}\) monounsaturated fatty acids, \({}^{3}\) omega-3 fatty acids, \({}^{4}\) omega-6 fatty acids, \({}^{5}\) polyunsaturatedated fatty acids.  
\end{table} 
Table 4: _Cont._