## 3 Results
### Volatile Compounds of Citrus and Other Nectar Honeys
#### 3.2.2 PCA: Characterization of Citrus Honey Samples of Different Geographical Origin (Part I)  
During PCA, the volatile compounds that showed high loading values were ethyl dodecanoate (F1, loading value of 0.871), ilac aldehyde C (F2, loading value of 0.690), \(\alpha\)-4-dimethyl-3-cyclohexene-1-acetaldehyde (F3, loading value of 0.494), ilac aldehyde D (F4, loading value of 0.657), 2-methylbutanal (F5, loading value of 0.503), methyl anthranilate (F6, loading value of 0.946), and para-cymene (F7, loading value of 0.930) (Table 2).  
The first two components (factors) explained 50.82% of the total variance (Figure 2a,b). In addition, the group of samples situated at the bottom (right quadrant) indicates that citrus honey samples C-Grc-11 to C-Grc-17, belonging to the group of citrus honey from Greece, showed high positive scores for component 1, and component 1 also has high loadings for octane, \(\alpha\)-pinene, octanal, nonane, decanal, nonanal, \(\beta\)-damascenone, 6-methyl-5-hepten-2-one, ethyl dodecanoate, ethyl hexadecanoate, and 3,4,5-trimethylphenol. The high loadings for volatile compounds reveal that these play a significant role in the overall variation of citrus honey from Argos (Greece) as indicators of its geographical origin. The analysis further reveals that the volatile compounds grouped together in Figure 2a,b at the bottom (right quadrant) are highly correlated.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \begin{tabular}{c} **Principal** \\ **Component** \\ **Analysis** \\ \end{tabular} & \begin{tabular}{c} **Enlyl** \\ **Dodecanoate** \\ **(F1)** \\ \end{tabular} & \begin{tabular}{c} **Lilac** \\ **(Aledehyde C)** \\ **(F2)** \\ \end{tabular} & \begin{tabular}{c} **Alpha-4-Dimethyl-3-** \\ **Cyclohexene-1-** \\ **Acetaldehyde** \\ **(F3)** \\ \end{tabular} & \begin{tabular}{c} **Alpha-4-Dimethyl-3-** \\ **Cydohexene-1-** \\ **D (F4)** \\ \end{tabular} & \begin{tabular}{c} **Aliac Aldehyde** \\ **D (F5)** \\ \end{tabular} & \begin{tabular}{c} **Methyl** \\ **Anthranilate** \\ **(F6)** \\ \end{tabular} & \begin{tabular}{c} **Para-Cymene** \\ **(F7)** \\ \end{tabular} \\ \hline \
\begin{tabular}{c} Eigenvalue \\ Variability (\%) \\ Cumulative \% \\ \end{tabular} & 10.889 & 5.374 & 2.348 & 1.976 & 1.602 & 1.298 & 1.225 \\
\begin{tabular}{c} Variability (\%) \\ Cumulative \% \\ \end{tabular} & 34.029 & 16.795 & 7.339 & 6.174 & 5.006 & 4.056 & 3.829 \\ \hline \multicolumn{7}{c}{PCs: Principal components. The compound with the highest loading value is highlighted in the corresponding principal component.} \\ \end{tabular}
\end{table}
Table 2: Cumulative variability explained by the 7 volatile compounds (factor variables, PCs) with eigenvalues greater than 1 during PCA.  
Figure 2: (**a**) Active volatile compounds (variables) of citrus honey related to geographical origin based on PCA. \(\varpi\): alpha; \(\beta\): beta. (**b**) Score plot (distribution of citrus honey samples) in the multi-dimensional space of PCA with respect to geographical origin.  
2.3 PCA: Characterization of Citrus and Other Nectar Honey Samples of Different Geographical Origin (Part II)  
For PCA in case a higher sample size of honey was used (n = 44) (citrus and nectar honey samples) the volatile compounds that had high loading values were: \(\alpha\)-pinene (loading value of 0.76), decanal (loading value of 0.72), benzeneacetonitrile (loading value of 0.78), lilac aldehyde C (loading value of 0.73), \(\alpha\),\(A\)-dimethyl-3-cyclohexene-1-acetaldehyde (loading value of 0.59), ethyl decanoate (loading value of 0.74), lilac aldehyde D (loading value of 0.62), furfural (loading value of 0.47), lilac aldehyde B (loading value of 0.54), and hotrienol (loading value of 0.64).