## 3 Results and Discussion  
### Volatile Composition of Olive Oil  
A total of 72 volatile compounds were identified for both harvesting periods. The volatiles were classified to the appropriate chemical class and consisted of nine acids, nineteen alcohols, thirteen aldehydes, seven esters, six hydrocarbons, seven ketones, six terpenoids and five miscellaneous compounds. The comparison of the volatile composition was studied within samples according to their growing area (Table 1) and according to their variety (Table S2). The identified compounds have already been reported by other researchers for olive oils from Spain [20; 21], Italy [32], Greece [12] and Tunisia [23]. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{4}{c}{**Content (\% of Total Identified Compounds)**} \\ \hline
**Compound** & **CRE** & **PEL** & **LES** & **RID 1** \\ \hline \multicolumn{4}{c}{_Acids_} \\ Acetic acid & 4.62 \({}^{\text{a}}\) & 3.04 \({}^{\text{b}}\) & 5.43 \({}^{\text{a}}\) & A \\ Propanoic acid & 0.24 \({}^{\text{a}}\) & 0.13 \({}^{\text{b}}\) & 0.13 \({}^{\text{b}}\) & A \\ Butanoic acid & 0.24 \({}^{\text{a}}\) & 0.12 \({}^{\text{b}}\) & 0.15 \({}^{\text{b}}\) & A \\
3-Methylbutanoic acid & 0.04 \({}^{\text{a}}\) & 0.03 \({}^{\text{b}}\) & 0.04 \({}^{\text{a}}\) & B \\ Hexanoic acid & 0.31 \({}^{\text{a}}\) & 0.25 \({}^{\text{ab}}\) & 0.23 \({}^{\text{b}}\) & A \\
2-Ethylhexanoic acid & 0.06 \({}^{\text{a}}\) & 0.08 \({}^{\text{a}}\) & 0.08 \({}^{\text{a}}\) & B \\ Heptanoic acid & 0.06 \({}^{\text{ab}}\) & 0.04 \({}^{\text{a}}\) & 0.06 \({}^{\text{b}}\) & B \\ Octanoic acid & 0.07 \({}^{\text{a}}\) & 0.09 \({}^{\text{a}}\) & 0.08 \({}^{\text{a}}\) & A \\ Nonanoic acid & 0.29 \({}^{\text{a}}\) & 0.46 \({}^{\text{b}}\) & 0.27 \({}^{\text{a}}\) & B \\ \multicolumn{4}{c}{_Alcohals_} \\ Ethanol & 5.23 \({}^{\text{a}}\) & 4.13 \({}^{\text{a}}\) & 3.98 \({}^{\text{a}}\) & A \\
1-Propanol & 0.02 \({}^{\text{a}}\) & 0.02 \({}^{\text{a}}\) & 0.04 \({}^{\text{b}}\) & A \\
2-Methyl-1-propanol & 0.11 \({}^{\text{a}}\) & 0.08 \({}^{\text{a}}\) & 0.29 \({}^{\text{b}}\) & A \\
3-Pentanol & 0.28 \({}^{\text{a}}\) & 0.54 \({}^{\text{b}}\) & 0.60 \({}^{\text{b}}\) & A \\
1-Butanol & 0.12 \({}^{\text{ab}}\) & 0.06 \({}^{\text{a}}\) & 0.13 \({}^{\text{b}}\) & A \\
1-Penten-3-ol & 10.56 \({}^{\text{a}}\) & 10.96 \({}^{\text{a}}\) & 7.83 \({}^{\text{b}}\) & A \\
3-Methyl-1-butanol & 0.20 \({}^{\text{a}}\) & 0.14 \({}^{\text{a}}\) & 0.60 \({}^{\text{b}}\) & A \\
1-Pentanol & 0.32 \({}^{\text{a}}\) & 0.35 \({}^{\text{a}}\) & 0.58 \({}^{\text{b}}\) & A \\ (Z)-2-Penten-1-ol & 4.29 \({}^{\text{a}}\) & 4.05 \({}^{\text{a}}\) & 3.18 \({}^{\text{b}}\) & B \\
1-Hexanol & 4.05 \({}^{\text{a}}\) & 4.80 \({}^{\text{a}}\) & 7.98 \({}^{\text{b}}\) & A \\ (E)-3-Hexen-1-ol & 0.16 \({}^{\text{a}}\) & 0.38 \({}^{\text{b}}\) & 0.28 \({}^{\text{b}}\) & B \\ (Z)-3-Hexen-1-ol & 6.22 \({}^{\text{a}}\) & 9.17 \({}^{\text{b}}\) & 10.42 \({}^{\text{b}}\) & B \\ (E)-2-Hexen-1-ol & 5.33 \({}^{\text{a}}\) & 6.72 \({}^{\text{a}}\) & 6.60 \({}^{\text{a}}\) & B \\
2-Ethyl-1-hexanol & 0.15 \({}^{\text{a}}\) & 0.31 \({}^{\text{b}}\) & 0.65 \({}^{\text{c}}\) & B \\
1-Octanol & 0.15 \({}^{\text{a}}\) & 0.10 \({}^{\text{b}}\) & 0.09 \({}^{\text{b}}\) & A \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Volatile composition of EVOOs according to the growing area of olive tree. The values represent the mean content (%) of the samples in each region. Data in the same row with different lowercase letters differ significantly (\(p<0.05\)). CRE: Crete; PEL: Peloponese; LES: Lesvos. Alcohols were the most numerous chemical class of volatile compounds detected, including mainly C5 and C6 compounds. 1-Penten-3-ol was the most prominent alcohol for olive oil samples from CRE and PEL (10.56% and 10.96%, respectively), whereas (Z)-3-hexen-1-ol was the dominant alcohol (10.42%) in LES samples.