## Results and Discussion
### Diversity of volatiles isolated by headspace solid-phase microextraction (HS-SPME)  
A total of 25 VOCs were identified in _A. fruticosa_ honey headspace by HS-SPME followed by GC and GC-MS. A representative chromatogram is presented in Figure 1.  
Benzene derivatives were the most abundant compounds in the headspace of _A. fruticosa_ honey, including 2-phenylethanol (38.3-58.4%), benzaldehyde (1.3-4.9%), phenylacetaldehyde (1.7-2.2%) and benzyl alcohol (1.1-1.3%), which have also been reported as ubiquitous in most honeys from a wide range of floral sources. However, very high percentage of 2-phenylethanol can be  
Figure 1: Representative TIC chromatogram of _A. fruticosa_ honey headspace VOCs isolated by HS-SPME. Numbers refer to the compounds listed in Table 1.  
noted as characteristic of this honey, although it is not specific marker. This aromatic compound, with a floral odor, was identified as a potent contributor to the aroma of linden, haze, caju, morrao de candeia and assa-piexe honeys [7,19,20]. Terpenes, particularly linalool derivatives, were another abundant group of the headspace VOCs (Table 1) including _trans_-linalool oxide (10.8-16.9%), _cis_-linalool oxide (1.3-3.2%), hotrienol (4.3-5.3%) and an isomer of lilac aldehyde (0.3-1.1%). Biogenetic studies have shown that lilac aldehydes are formed from linalool by direct hydroxylation of linalool at C8 to (_E_)-8-hydroxylinalool and further to (_E_)-8-oxolinalool, that is converted to lilac alcohols that undergo oxidation to lilac aldehydes [21]. Alternatively, epoxidation of linalool gives 6,7-epoxylinalool which undergoes further oxidation and heat and/or acidic conditions form two furan linalool oxides [22]. Minor percentages (4.3-5.3%) of hotrienol were also identified. Since no heat was applied during the VOC isolation process, hotrienol was probably formed during honey ripening \begin{table}
\begin{tabular}{l l c c c c} \hline \multirow{2}{*}{No.} & \multirow{2}{*}{Compound} & \multirow{2}{*}{RI} & \multicolumn{4}{c}{Area percentage (\%)} \\ \cline{3-6}  & & & Min. & Max. & Av. & SD. \\ \hline
1. & Methyl sulfide & \(\circ\) 900 & 0.0 & 0.3 & 0.13 & 0.15 \\
2. & Dimethyl disulfide & \(\circ\) 900 & 0.0 & 0.2 & 0.10 & 0.10 \\
3. & Octanea & \(\circ\) 900 & 0.9 & 1.6 & 1.33 & 0.38 \\
4. & Furfurala & \(\circ\) 900 & 0.5 & 1.4 & 0.97 & 0.45 \\
5. & Nonanea & 900 & 0.0 & 0.5 & 0.27 & 0.25 \\
6. & 1-(2-Furanyl)- ethanone & 914 & 0.0 & 0.2 & 0.10 & 0.10 \\
7. & Benzaldehydea & 965 & 1.3 & 4.9 & 2.97 & 1.81 \\
8. & 2,4-Dimethyl-3,6-dihydro-2H-pyran & 969 & 1.0 & 1.6 & 1.20 & 0.35 \\
9. & Hexanoic acida & 974 & 0.4 & 0.7 & 0.50 & 0.17 \\
10. & Benzyl alcohola & 1037 & 1.1 & 1.3 & 1.20 & 0.10 \\
11. & Phenylacetaldehydea & 1048 & 1.7 & 2.2 & 2.00 & 0.26 \\
12. & _trans_-Linalool oxide (furan type) & 1076 & 10.8 & 16.9 & 14.23 & 3.12 \\
13. & _cis_-Linalool oxide (furan type) & 1091 & 1.3 & 3.2 & 2.37 & 0.97 \\
14. & Linaloola & 1101 & 1.0 & 2.1 & 1.53 & 0.55 \\
15. & Hotrienol & 1106 & 4.3 & 5.3 & 4.80 & 0.50 \\
16. & 2-Phenylethylanola & 1116 & 38.3 & 58.4 & 47.30 & 10.21 \\
17. & Isophoronea & 1124 & 0.1 & 1.2 & 0.67 & 0.61 \\
18. & Phenylacetonitrile & 1142 & 0.8 & 1.0 & 0.90 & 0.10 \\
19. & 4-Ketoisophorone & 1147 & 0.0 & 0.4 & 0.17 & 0.21 \\
20. & Lilac aldehydea & 1154 & 0.3 & 1.1 & 0.73 & 0.40 \\
21. & Pinocarvone & 1166 & 0.1 & 0.9 & 0.57 & 0.42 \\
22. & Nonan-1-ola & 1175 & 1.0 & 2.8 & 1.77 & 0.93 \\
23. & Nonanoic acida & 1273 & 0.7 & 2.1 & 1.43 & 0.70 \\
24. & 4-Vinyl-2-methoxy-phenol & 1314 & 0.0 & 0.6 & 0.30 & 0.30 \\
25. & (_E_)-\(\beta\)-Damascenone & 1385 & 0.7 & 1.5 & 1.07 & 0.40 \\ \cline{2-2} \cline{3-6}  & & & 89.7-92.9\% & & & \\ \hline \end{tabular} RI = retention indices on HP-5 MS column; Min. = minimal percentage; Max. = maximal percentage; Av. = average percentage; SD. = standard deviation; = ‘-identification confirmed with reference compound; \({}^{**}\) - correct isomer not identified.  
\end{table} 
Table 1: _A. fruticosa_ honey VOCs isolated by HS-SPME. [23].