## 3 Results and Discussion
### Estimation of Volatiles over Ripeting  
The volatile fraction resulting from avocado oil extraction with petroleum ether and isolated by the HS-SPME technique gave mainly terpenoids and hydrocarbons (non-terpenoids). In contrast to previous studies, trace amounts of aldehydes, ketones, and other compounds were detected [25; 33; 34; 36; 37], which may be attributed to the sampling method or to the differences among avocado varieties. The ripening stages (breaking, ripe, and overripe) indicated major differences in the semi-quantification of volatile compounds. The hydrocarbon (non-terpenoids) contents were found to be 14.41, 6.57, and 17.62 mg\(\cdot\)kg\({}^{-1}\) for breaking, ripe, and overripe samples over SE and 14.80, 2.89, and 14.14 mg\(\cdot\)kg\({}^{-1}\) over UAE, respectively. The corresponding terpenionids contents were found to be 18.44, 24.68, and 14.27 mg\(\cdot\)kg\({}^{-1}\) for breaking, ripe, and overripe samples over SE and 18.67, 28.74, and 15.50 mg\(\cdot\)kg\({}^{-1}\) over UAE. The above results show that, during maturation, the volatile fraction fluctuates. On the fourth day of maturation, the abundance of hydrocarbons was significantly lower (\(p<0.05\)) compared with the first day, while it increased on the eighth day. In contrast, the abundance of terpenids was significantly higher (\(p<0.05\)) on the fourth day of maturation. This change in volatility was observed in both cases of the extraction techniques (Figure 3). The abundance of hydrocarbons and terpenoids was examined by multivariate analysis of variance in comparison with the ripening stages. The Scheffe post hoc test was used to investigate which pairs of means were significant, and detailed results are presented in Table 2. It is evident that 21 of 44 total volatiles were statistically significant (\(p<0.05\)). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Volatile Compounds**} & \multirow{2}{*}{**CAS Number**} & \multirow{2}{*}{**RT a**} & \multirow{2}{*}{**RI b**} & \multicolumn{6}{c}{**Soxhlet**} & \multicolumn{3}{c}{**UAE**} \\ \cline{5-10}  & & & & **Breaking** & & **Ripe** & **Overripe** & **Breaking** & **Ripe** & **Overripe** \\ \hline \multicolumn{10}{c}{**Aldehydes**} \\ \hline nonanal & 124-19-6 & 17.7 & 1104 & 0.08 & 0.11 & 0.07 & 0.08 & 0.16 & 0.02 \\ \hline \multicolumn{10}{c}{**Ketones**} \\ \hline octan-2-one & 111-13-7 & 10.6 & 907 & 0.56 & 0.28 & 0.48 & 0.27 & 0.12 & 0.19 \\ \hline \multicolumn{10}{c}{**Others**} \\ \hline trans-decahydronaphthalene & 493-02-7 & 16.1 & 1057 & 0.34 & 0.10 & 0.25 & 0.27 & 0.02 & 0.27 \\ (15,45)-1,6-dimethyl-4-propan-2-yl-1,2,3,4-tetrahydroaphthalene & 72937-55-4 & 30.8 & 1519 & 0.13 & 0.24 & 0.19 & 0.13 & 0.23 & 0.22 \\ (calamene) & & & & & & & & & \\ \hline \hline \end{tabular}  
* RT: Retention time (min); b RI: Experimental retention index.  
\end{table} 
Table 1: _Cont._  
Figure 3: The variation of volatility during three ripening stages. Three volatiles significantly differed between the ripening stages, including 1-methyl-4-(propan-2-ylidene)cyclohex-1-ene; 1-methyl-4-(prop-1-en-2-yl)benzene (p-cymenene); and (15,8 aR)-4,7-dimethyl-1-propan-2-yl-1,2,3,5,6,8a-hexahdronaphthalene (\(\delta\)-cadinene). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{5}{c}{**Multiple Comparisonsa**} \\ \hline
**No.