## 3 Results and Discussion
### Volatile Constituents
#### 3.5.1 Feeds and Olive Cake
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compounds** & **LRI** & **CTR** & **ECO** & **Olive Cake** \\ \hline Acids & & & & \\ Acetic acid & 1455 & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) & 0.36 \(\pm\) 0.02\({}^{\text{b}}\) \\ Propionic acid & 1540 & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) & 0.23 \(\pm\) 0.01\({}^{\text{b}}\) \\
2-Methyl-propanoic acid & 1566 & 0.62 \(\pm\) 0.04\({}^{\text{b}}\) & 0.55 \(\pm\) 0.04\({}^{\text{b}}\) & 0.28 \(\pm\) 0.02\({}^{\text{a}}\) \\ Butanoic acid & 1629 & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) & 0.94 \(\pm\) 0.06\({}^{\text{b}}\) \\
2-Methyl-butanoic acid & 1666 & 3.14 \(\pm\) 0.12\({}^{\text{c}}\) & 2.64 \(\pm\) 0.22\({}^{\text{b}}\) & 0.85 \(\pm\) 0.05\({}^{\text{a}}\) \\ Hexanoic acid & 1844 & 1.62 \(\pm\) 0.18\({}^{\text{a}}\) & 5.02 \(\pm\) 0.41\({}^{\text{b}}\) & 5.58 \(\pm\) 0.41\({}^{\text{b}}\) \\ Heptanoic acid & 1950 & tr\({}^{\text{a}}\) & 0.77 \(\pm\) 0.06\({}^{\text{b}}\) & 0.85 \(\pm\) 0.06\({}^{\text{b}}\) \\ Octanoic acid & 2060 & 0.26 \(\pm\) 0.03\({}^{\text{a}}\) & 0.94 \(\pm\) 0.07\({}^{\text{b}}\) & 1.06 \(\pm\) 0.08\({}^{\text{b}}\) \\ Nonanoic acid & 2165 & tr\({}^{\text{a}}\) & 0.71 \(\pm\) 0.03\({}^{\text{b}}\) & 0.74 \(\pm\) 0.04\({}^{\text{b}}\) \\ Tetradecanoic acid & 2694 & 0.90 \(\pm\) 0.07\({}^{\text{a}}\) & 0.87 \(\pm\) 0.07\({}^{\text{a}}\) & 0.39 \(\pm\) 0.02\({}^{\text{b}}\) \\ Pentadecanoic acid & 2799 & 0.26 \(\pm\) 0.03\({}^{\text{b}}\) & 0.26 \(\pm\) 0.03\({}^{\text{b}}\) & tr\({}^{\text{a}}\) \\ Hexadecanoic acid & 2906 & 3.23 \(\pm\) 0.16\({}^{\text{a}}\) & 3.63 \(\pm\) 0.18\({}^{\text{b}}\) & 3.89 \(\pm\) 0.31\({}^{\text{b}}\) \\ All & & 10.02 \(\pm\) 0.63\({}^{\text{a}}\) & 15.39 \(\pm\) 1.11\({}^{\text{b}}\) & 15.18 \(\pm\) 1.08\({}^{\text{b}}\) \\ \hline Aldehydes & & & & \\ Pentanal & 985 & 0.85 \(\pm\) 0.05\({}^{\text{a}}\) & 1.23 \(\pm\) 0.07\({}^{\text{b}}\) & 0.66 \(\pm\) 0.04\({}^{\text{a}}\) \\ Hexanal & 1085 & 9.79 \(\pm\) 0.57\({}^{\text{c}}\) & 8.45 \(\pm\) 0.42\({}^{\text{b}}\) & 4.42 \(\pm\) 0.22\({}^{\text{a}}\) \\ Heptanal & 1188 & 1.21 \(\pm\) 0.08\({}^{\text{a}}\) & 2.44 \(\pm\) 0.17\({}^{\text{b}}\) & 2.03 \(\pm\) 0.14\({}^{\text{b}}\) \\ Octanal & 1292 & 3.54 \(\pm\) 0.14\({}^{\text{a}}\) & 5.76 \(\pm\) 0.23\({}^{\text{b}}\) & 6.86 \(\pm\) 0.27\({}^{\text{c}}\) \\ (Z)-2-Heptension & 1328 & 0.58 \(\pm\) 0.03\({}^{\text{a}}\) & 0.50 \(\pm\) 0.02\({}^{\text{a}}\) & 1.39 \(\pm\) 0.07\({}^{\text{b}}\) \\ Nonanal & 1395 & 3.71 \(\pm\) 0.19\({}^{\text{a}}\) & 10.31 \(\pm\) 0.61\({}^{\text{b}}\) & 24.04 \(\pm\) 1.44\({}^{\text{c}}\) \\ (E)-2-Octenal & 1431 & 0.96 \(\pm\) 0.06\({}^{\text{a}}\) & 0.92 \(\pm\) 0.05\({}^{\text{a}}\) & 0.80 \(\pm\) 0.04\({}^{\text{a}}\) \\ Decanal & 1499 & 0.37 \(\pm\) 0.01\({}^{\text{a}}\) & 0.42 \(\pm\) 0.02\({}^{\text{a}}\) & 1.25 \(\pm\) 0.05\({}^{\text{b}}\) \\ Benzaldehyde & 1527 & 0.24 \(\pm\) 0.02\({}^{\text{a}}\) & 0.55 \(\pm\) 0.04\({}^{\text{a}}\) & 2.01 \(\pm\) 0.14\({}^{\text{b}}\) \\ (E)-2-Nonanal & 1535 & 0.39 \(\pm\) 0.02\({}^{\text{b}}\) & 0.26 \(\pm\) 0.02\({}^{\text{b}}\) & tr\({}^{\text{a}}\) \\ (E)-2-Decenal & 1645 & 0.29 \(\pm\) 0.01\({}^{\text{a}}\) & 0.93 \(\pm\) 0.05\({}^{\text{b}}\) & 0.80 \(\pm\) 0.04\({}^{\text{b}}\) \\ (Z)-8-Undecenal & 1750 & tr\({}^{\text{a}}\) & 0.30 \(\pm\) 0.02\({}^{\text{b}}\) & tr\({}^{\text{a}}\) \\ All & & 21.95 \(\pm\) 1.18\({}^{\text{a}}\) & 32.07 \(\pm\) 1.72\({}^{\text{b}}\) & 44.27 \(\pm\) 2.45\({}^{\text{c}}\) \\ \hline Alcohols & & & & \\ Ethanol & 937 & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) & 0.23 \(\pm\) 0.01\({}^{\text{b}}\) \\
5-Ethyl-2-heptanol & 1121 & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) & 0.25 \(\pm\) 0.02\({}^{\text{b}}\) \\
1-Butanol & 1143 & 0.32 \(\pm\) 0.02\({}^{\text{b}}\) & 0.29 \(\pm\) 0.01\({}^{\text{b}}\) & tr\({}^{\text{a}}\) \\
2-Methyl-1-butanol & 1158 & 0.26 \(\pm\) 0.01\({}^{\text{b}}\) & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) \\
3-Methyl-1-butanol & 1205 & 0.39 \(\pm\) 0.02\({}^{\text{b}}\) & 0.27 \(\pm\) 0.01\({}^{\text{a}}\) & 0.27 \(\pm\) 0.02\({}^{\text{a}}\) \\
1-Pentanol & 1247 & 6.27 \(\pm\) 0.34\({}^{\text{c}}\) & 4.75 \(\pm\) 0.19\({}^{\text{b}}\) & tr\({}^{\text{a}}\) \\ Heptan-2-ol & 1315 & 0.35 \(\pm\) 0.02\({}^{\text{b}}\) & tr\({}^{\text{a}}\) & tr\({}^{\text{a}}\) \\
3-Methyl-1-pentanol & 1351 & 25.90 \(\pm\) 1.18\({}^{\text{c}}\As results from the table, a large number of volatiles were identified, belonging to different classes of substances such as aliphatic acids, alcohols, ketones, esters, and aldehydes; moreover, terpenes, lactones, furans, and aromatic compounds were identified too.