## 3 Results and Discussion
### Volatile Constituents
#### 3.5.2 Milk and Cheese  
In Table 6, the volatile percentage composition in single compounds and classes of substances for the milk and cheese, both CTR and ECO, are reported. The volatiles belonged to different classes of substances, all these well known in the volatile fraction of dairy products, such as aliphatic acids, alcohols, ketones, esters, and aldehydes; moreover, terpenes, lactones, and aromatic compounds were identified too. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Cheese**} & \multicolumn{4}{c}{**Milk**} \\ \hline
**Compounds** & **LRI** & **CTR** & **ECO** & & **CTR** & **ECO** & \\ \hline Acids & & & & & & & \\ Acetic acid & 1460 & 0.90 \(\pm\) 0.06 b  & 0.33 \(\pm\) 0.02 a  & **2.19 \(\pm\) 0.15 b  & 0.13 \(\pm\) 0.01 a  & **\(\ast\ast\)** \\ Propanoic acid & 1543 & tr a  & 0.46 \(\pm\) 0.03 b  & **\(\ast\ast\)** & - & ns \\ Butanoic acid & 1631 & 3.24 \(\pm\) 0.16 b  & 1.14 \(\pm\) 0.07 a  & 0.51 \(\pm\) 0.04 a  & 0.93 \(\pm\) 0.03 b  & \(\ast\)* \\ Hexanoic acid & 1740 & 9.09 \(\pm\) 0.63 b  & 3.90 \(\pm\) 0.31 a  & 1.07 \(\pm\) 0.05 a  & 1.05 \(\pm\) 0.04 a  & ns \\ Heptanoic acid & 1954 & 0.22 \(\pm\) 0.01 a  & 0.16 \(\pm\) 0.01 a  & 0.37 \(\pm\) 0.02 b  & Tr a  & * \\ Octanoic acid & 2062 & 3.79 \(\pm\) 0.18 b  & 2.88 \(\pm\) 0.14 a  & 1.21 \(\pm\) 0.06 a  & 1.65 \(\pm\) 0.08 b  & ns \\ Nonanoic acid & 2170 & 2.02 \(\pm\) 0.10 a  & 1.96 \(\pm\) 0.08 a  & ns & 3.49 \(\pm\) 0.21 b  & 1.09 \(\pm\) 0.06 a  & **\(\ast\ast\)** \\ (E)-2-Octenoic acid & 2184 & tr a  & 0.36 \(\pm\) 0.02 b  & ** - & - & ns \\ Decanoic acid & 2276 & 2.24 \(\pm\) 0.11 b  & 1.87 \(\pm\) 0.07 a  & 5.21 \(\pm\) 0.36 b  & 4.00 \(\pm\) 0.28 a  & ns \\ (E)-9-Decenoic acid & 2332 & - & - & ns & 0.08 \(\pm\) 0.01 a  & tr a  & ns \\ Undecanoic acid & 2379 & 0.27 \(\pm\) 0.02 a  & 0.23 \(\pm\) 0.02 a  & ns & 0.26 \(\pm\) 0.02 a  & 0.29 \(\pm\) 0.02 a  & ns \\ (E)-2-Decenoic acid & 2399 & 0.15 \(\pm\) 0.01 a  & 0.37 \(\pm\) 0.03 a  & * & 0.24 \(\pm\) 0.02 a  & 0.32 \(\pm\) 0.03 a  & ns \\ Benzoic acid & 2430 & - & - & ns & 0.32 \(\pm\) 0.01 a  & 0.29 \(\pm\) 0.02 a  & ns \\ Dodecanoic acid & 2488 & 1.70 \(\pm\) 0.12 a  & 2.03 \(\pm\) 0.16 a  & ns & 2.32 \(\pm\) 0.13 a  & 3.25 \(\pm\) 0.23 b  & ns \\ Trideanoic acid & 2587 & tr a  & 0.23 \(\pm\) 0.01 a  & * & 0.34 \(\pm\) 0.02 a  & 0.54 \(\pm\) 0.04 b  & ns \\ Tetradecanoic acid & 2698 & 6.27 \(\pm\) 0.25 a  & 11.57 \(\pm\) 0.81 b  & * & 22.69 \(\pm\) 1.34 a  & 25.67 \(\pm\) 1.26 b  & ns \\ Pentadecanoic acid & 2799 & 2.50 \(\pm\) 0.15 a  & 3.34 \(\pm\) 0.23 b  & ns & 3.13 \(\pm\) 0.10 a  & 3.44 \(\pm\) 0.08 b  & ns \\ Hexadecanoic acid & 2810 & 24.42 \(\pm\) 1.22 a  & 41.36 \(\pm\) 1.65 b  & * & 43.50 \(\pm\) 2.26 a  & 48.72 \(\pm\) 2.59 b  & All & 56.81 \(\pm\) 3.02 a  & 72.19 \(\pm\) 3.66 b  & * & 86.93 \(\pm\) 4.80 a  & 91.37 \(\pm\) 4.77 b  & ns \\ Short-Medium & 2192 & 1.28 b  & 13.66 \(\pm\) 0.80 a [FOOTNOTE:a]Aliphatic acids are the main classes of substances in the milk and cheese samples. The short-chain acids are responsible for the sour taste, while long-chain acids are odorless; the unsaturated ones such as (E)-2-Decenoic acid have a more intense odor. Short-chain free fatty acids (SCFFA) have strong sweaty, cheessy, and lipolysis notes, low flavor thresholds, and are considered key aroma compounds in dairy products. In particular, butanoic acid (cheessy, dairy, buttery) has been demonstrated to be the marker aroma compound of raw cow milk. Contrastingly, medium-chain free fatty acids (MCFFA) such as C\({}_{10}\) and C\({}_{12}\), for their high flavor thresholds, influence the dairy products' aroma less. Comparing the acid amount in CTR and ECO milk, there was a higher amount in the ECO, which had the highest amount of long-chain free fatty acids (LCFFA), while the CTR had the highest amounts of medium- and short-chain ones. Thus, the ECO cheese showed a healthier FFA profile.