## 3 Results and Discussion
### Volatile Compounds  
Volatile compounds are responsible for the aroma profile of olive fruits. Consequently, the volatile compounds profile is considered a suitable tool for authentication of virgin olive oils. In total, 60 volatile compounds were identified in the WOF used, composed of 21 terpenoids, 15 hydrocarbons, 9 aldehydes, 8 alcohols, 2 ketones, 2 esters, and 3 miscellaneous compounds (Table 6). Most of the volatile compounds in the WOF were terpenoids (46.84%), followed by hydrocarbons (20.21%) and aldehydes (10.95%), whereas the content of the rest of the classes was slightly lower (<12%). Regarding ketones, their percentage was recorded at low levels (5.09%), with acetoin and 6-methyl-5-heptene-2-one being the predominant compounds. The main volatile compounds of unripe fruits were \(\beta\)-ocimene (13.63%), followed by \(\alpha\)-copaene (9.64%), \(\alpha\)-farnesene (8.03%), and \(\alpha\)-phellandrene (5.04%), all of them belonging to terpenoids. \(\beta\)-ocimene (floral, herbal, sweet note) along with \(\alpha\)-farnesene (woody, green, floral, herbal note) and \(\alpha\)-copaene (woody, spicy note) have already been identified as volatile markers in Greek olive oils [79]. The presence of many mono- and sequiterpenes, even if in low amounts, in the unripe fruits has also been mentioned by [PERSON] et al. [80]. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**No.** & **Volatile Compound** & **RI (exp) 1** & **RI (lit) 2** & **\% Area 3** & **Odor Description 4** \\ \hline \multicolumn{5}{c}{Aldehydes} \\
1 & **2-Methyl-butanal** & 646 & 664 & 0.07 \(\pm\) 0.01 & Musty, coffee, nutty \\
2 & **Hexanal** & 803 & 801 & 3.80 \(\pm\) 0.25 & Green, apple \\
3 & **(E)-2-Hexanal** & 861 & 853 & 4.78 \(\pm\) 0.02 & Apple-like, green, leaf \\
4 & **Heptanal** & 904 & 902 & 0.21 \(\pm\) 0.02 & Fresh, fatty, green, herb, wine \\
5 & **(E,E)-2,4-heptdalen** & 1001 & 998 & 0.24 \(\pm\) 0.01 & Fatty, nut \\
6 & **Octanal** & 1005 & 1005 & 0.27 \(\pm\) 0.01 & Fatty, lemon \\
7 & **Benzene acetaldehyde** & 1053 & 1050 & 0.45 \(\pm\) 0.04 & Pungent, honey, fruity, \\
8 & **Nonanal** & 1106 & 1102 & 1.00 \(\pm\) 0.07 & Rose, fresh, orris, orange, fatty \\
9 & **Decanal** & 1208 & 1204 & 0.17 \(\pm\) 0.01 & Soap, orange peel, tallow \\ \hline \multicolumn{5}{c}{Total Aldehydes} \\
10 & **Acetoin** & 695 & 709 & 3.31 \(\pm\) 0.18 & Creamy, fatty \\
11 & **6-Methyl-5-Heptene-2-one** & 989 & 986 & 1.79 \(\pm\) 0.02 & Citrus-like, fruity \\ \hline \multicolumn{5}{c}{Total Ketones} \\  & \multicolumn{1}{c}{Alcohols} \\
12 & **1-Methoday-2-propanol** & 649 & 672 & 0.24 \(\pm\) 0.03 & - \\
13 & **3-Methyl-1-butanol** & 721 & 727 & 0.19 \(\pm\) 0.01 & Fermented \\
14 & **2,3-Butanediol** & 785 & 785 & 2.42 \(\pm\) 0.05 & Creamy \\
15 & **2,3-Butanediol isomer** & 797 & 806 & 0.67 \(\pm\) 0.01 & Creamy \\
16 & **1-Hexanol** & 875 & 867 & 0.62 \(\pm\) 0.01 & Herbal, pungent, alcoholic \\
17 & **1-Hexanol 2-ethyl-** & 1032 & 1029 & 0.25 \(\pm\) 0.01 & Herbal, pungent, alcoholic \\
18 & Benzyl alcohol & 1043 & 1034 & 0.49 \(\pm\) 0.02 & Floral, sweet, phenolic \\
19 & **Phenethyl alcohol** & 1119 & 1110 & 0.47 \(\pm\) 0.06 & Floral, sweet, bread \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Volatile composition (% of total area of identified compounds) of wild olive fruit as determined by solid-phase microextraction/gas chromatography-mass spectrometry (SPME-GC-MS) method.