## 4 Discussion  
Considering citrus honey samples, the iliac isomers (I-IV) are of great importance, since these volatile compounds hold a high proportion in the total volatile fraction of citrus honey. It has been documented in previous studies [3; 4; 8] that these volatile compounds may potentially be considered as \"key volatile compounds\" in citrus honey. However, in more recent studies it was reported that ilac aldehydes could potentially contribute to the aroma of Spanish sunflower and thyme honey [6] and of Turkish pine honey [19]. Some other aldehydes such as octanal, nonanal, and decanal have been also identified in citrus honey [3; 4; 8]. In the present study, nonanal and decanal could aid to the geographical discrimination of citrus honey (Table 1). 2-Methylbutanal (which comprises a leucine- and isoleucine-derived volatile) was identified only in Egyptian citrus honey samples. Benzaldehyde, with an almond-like and pleasant aroma was identified in higher amount (mg/kg) in Moroccan and Greek citrus honey samples compared to Egyptian and Spanish citrus honey samples. However, the other nectar honey samples studied had the highest amount (mg/kg) of benzaldehyde. This compound has previously been reported to contribute to the volatile fraction of Greek and Spanish citrus honey [3; 4; 8]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**LDA**} & \multirow{2}{*}{**Prediction Rate**} & \multicolumn{6}{c}{**Predicted Group Membership**} & \multicolumn{2}{c}{**Total**} \\ \cline{3-8}  & & **Geographical Origin** & **Cirus Honey** & **Cirus Honey** & **Cirus Honey** & **Other** & **Cirus and Nectar** & **Cirus and Nectar** \\  & & & **Home** & **Home** & **Home** & **Home** & **Honey** & **Nectar** & **Honey** \\  & & & **Egypt** & **Morocco** & **Greece** & **Spain** & **from Greece** & **Samples** \\ \hline \multirow{10}{*}{Counts-validated b\({}^{c}\)} & \multicolumn{2}{c}{Citrus honey from Egypt} & \multicolumn{2}{c}{5} & 1 & 1 & 0 & 0 & 7 \\  & \multicolumn{2}{c}{Citrus honey from Morocco} & \multicolumn{2}{c}{1} & 4 & 1 & 0 & 0 & 6 \\  & \multicolumn{2}{c}{Counts Honey from Greece} & \multicolumn{2}{c}{3} & 1 & 12 & 1 & 0 & 17 \\  & \multicolumn{2}{c}{Citrus honey from Spain} & \multicolumn{2}{c}{0} & 0 & 1 & 7 & 0 & 8 \\  & \multicolumn{2}{c}{Other nectar honey} & \multicolumn{2}{c}{0} & 0 & 0 & 0 & 6 & 6 \\  & \multicolumn{2}{c}{from Greece} & \multicolumn{2}{c}{0} & \multicolumn{2}{c}{0} & 0.0 & 0 & 6 & 6 \\ \cline{2-8}  & \multicolumn{2}{c}{Citrus honey from Greece} & \multicolumn{2}{c}{71.4} & 14.3 & 14.3 & 0.0 & 0.0 & 100.0 \\  & \multicolumn{2}{c}{Citrus honey from Morocco} & \multicolumn{2}{c}{16.7} & 66.7 & 16.7 & 0.0 & 0.0 & 100.0 \\  & \multicolumn{2}{c}{Citrus honey from Greece} & \multicolumn{2}{c}{17.6} & 5.9 & 70.6 & 5.9 & 0.0 & 100.0 \\  & \multicolumn{2}{c}{Citrus honey from Spain} & \multicolumn{2}{c}{0.0} & 0.0 & 12.5 & 87.5 & 0.0 & 100.0 \\  & \multicolumn{2}{c}{Other nectar honey} & \multicolumn{2}{c}{0.0} & 0.0 & 0.0 & 0.0 & 100.0 & 100.0 \\  & \multicolumn{2}{c}{from Greece} & \multicolumn{2}{c}{0.0} & 0.0 & 0.0 & 0.0 & 100.0 & 100.0 \\ \hline \hline \end{tabular}  
* a 97.7% of original method grouped cases correctly classified. b Cross-validation is performed only for those cases in the analysis. In the cross-validation method, each case is classified by the functions derived from all cases other than that particular case. c 77.3% of cross-validation method grouped cases correctly classified.  
\end{table} 
Table 3: _Cont._Regarding furan derivatives, furfural (furan-2-carbaldehyde) and 5-methyl-2-furaldehyde are owed to the thermal pre-treatment of honey during the HS-SPME [15], heat processing or storage, and should not be considered as markers of botanical or geographical origin, as reported by [PERSON] et al. [4]. Even though significant differences were detected in the composition (mg/kg) of furfural, with respect to geographical origin of citrus honey, we are in line with the report of [PERSON] et al.