## 3 Results and Discussion
### Characterization of Essential Oils  
#### 3.1.1 Chemical Composition  
Essential oils are complex mixtures of sometimes more than 200 components, but the main components (with the highest percentage) are responsible for the bioactivity and chemical properties of the essential oil. The extraction yield of an essential oil, as well as its composition, is influenced by many environmental and processing factors. Growth environment, harvest season, climatic conditions, genetic origin of the plants, vegetative plant phases and sapling time, extraction method and quantification techniques may have impacts on the essential oil's composition [13; 28; 35]. For these reasons, the identification of essential oil components is mandatory. The identification of the essential oils' components was elucidated through mass spectral data, the retention time, and calculated retention indices. The obtained data were then compared to the available literature and NIST library databases. The results are presented in Table 3.  
The identified components in lemon essential oil accounted for 95.92% of the total composition. The major components were limonene (67.39%), \(\gamma\)-terpinene (10.86%), and \(\beta\)-pinene (8.11%). Myrcene and \(\alpha\)-pinene were present in percentages of 1.90 and 2.12%, while all other components were in percentages lower than 1%. [PERSON] et al. [12] analyzed _C. lemon \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Plant Material** & **Yield (exp), \%** & **Yield (lit) 1, \%** & **Ref.** \\ \hline Lemon peel & 4.90 & 1.24–3.00 & [25; 26] \\ Bay leaf & 0.74 & 0.57–3.25 & [27; 28] \\ Clove buds & 9.43 & 3.80–18.00 & [29; 30] \\ Nutmeg & 9.19 & 3.40–17.00 & [31; 32] \\ Star anise & 9.65 & 3.00–9.00 & [33; 34] \\ Oregano & 1.62 & 1.10–2.90 & [17; 35] \\ \hline \hline \end{tabular}  
* The literature yields are given for the lowest and highest reported yields.  
\end{table} 
Table 2: Yield of essential oils—experimental data compared to the published data. peel from India with major components of limonene (55.40%) and neral (10.39%), while _trans_-verbenol was present in the intermediate concentrations (6.43%). The predominant compound in lemon essential oil from Egypt was \(\beta\)-pinene (31.38%), while the amount of limonene was only 14.57% [13]. Limonene (29.52%) was also dominant in lemon essential oil from Iraq, followed by \(\beta\)-pinene (23.89%), R-citronellal (15.10%) and thymol (9.79%) [36]. On the other hand, lemon essential oil from Italy showed a more similar content to our sample, with limonene as the highly predominant compound (64.13%) followed by \(\beta\)-pinene (12.59%) and \(\gamma\)-terpinene (10.20%) [37]. For the bay leaf essential oil, 94.54% of the components were identified. Eucalypt was present in the highest percentage (43.48%), \(\alpha\)-terpinyl-acetate and methyl-eugenol were represented at 9.49 and 6.10%, while linalool, \(\alpha\)-pinene, \(\beta\)-pinene, and terpinene-4-ol were present in percentages of 4.30, 4.28, 3.24, and 3.10%, respectively. These findings agree with analysis of bay leaf essential oil from Spain, which was also rich in eucalypt (50.57%) and had significant amounts of \(\alpha\)- and \(\beta\)-pinene (6.81 and 2.36%), linalool (6.78%), \(\alpha\)-terpinyl-acetate (10.25%), methyl-eugenol (2.74%) and terpinene-4-ol (2.24%) [38]. Similar results were found in bay leaf essential oil from Turkey with main components linalool (41.4%), \(\alpha\)-pinene (5.9%) \(\alpha\)-terpinyl-acetate (5.7%), \(\beta\)-pinene (4.5%), and terpinene-4-ol (1.8%) [14]. The sample from Morocco had a lower percentage of eucalypt (36.58%), a higher percentage of \(\alpha\)-terpinyl-acetate (15.42%), and sabinene as one of main compounds (12.08%) [4]. Clove essential oil has two predominant components--eugenol (61.44%) and \(\beta\)-caryophyllene (24.64%). Of the components, 99.27% were identified. Eugenol-acetate, \(\alpha\)-humulene, \(\alpha\)-copaene, and \(\delta\)-cadinene were present in amounts higher than 1%.