## 3 Results and Discussion
### Evaluation of SAFE, SDE and SPME Extracts by GC\(\times\)GC
Moreover, in the case of aroma-active components determination, those factors are especially important. In the presented study, among the three applied techniques, the most suitable for the determination of aroma-active components was the SAFE method, mostly because it is an exhaustive extraction technique and does not require high temperatures as with the SDE technique. Most importantly, SAFE extraction led to the isolation of the greatest number of aroma active components. However, in the case of non-targeted analysis of volatiles in _Brassica_, all applied techniques might be useful, because the composition of extracted components differs between them. The common feature of all extracts was the majority of alcohols and sulfides. The main differences \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Compound** & **Molecular Weight** & **SDE \%** & **SAFE \%** & **SPME \%** \\ \hline n-pentyl isothiamate & 129 & 0.05 & 0.02 & 0.01 \\ hexanoic acid, methyl ester & 130 & nd & nd & 0.49 \\
1H-indole, 3-methyl- & 131 & 0.43 & 0.01 & 0.01 \\ benzenepropanenitrile & 131 & 0.89 & 0.34 & 0.08 \\ S-methyl pentanethoate & 132 & 0.01 & 0.03 & nd \\ benzyl isocyanate & 133 & nd & 0.01 & nd \\ benzothiazole & 135 & 0.05 & 0.75 & nd \\
3-ethyl-1,5-catalene & 138 & 0.63 & 0.17 & 0.18 \\ benzene, 1,2-dimethoxy- & 138 & nd & 0.51 & 0.21 \\furan, 2-pentyl- & 138 & 1.32 & 0.09 & 0.73 \\ thiophene, 3.4-diethyl- & 140 & 0.03 & nd & nd \\ cyclohexane, isothiçanoate- & 141 & nd & nd & nd \\
2-hexen-1-ol, acetate, (Z)- & 142 & 0.47 & nd & nd \\ nonanal & 142 & 0.23 & 0.29 & 0.10 \\
4-methylpentyl isothiamate & 143 & nd & 0.06 & nd \\ hexane, 1-isothiocyanato- & 143 & 0.09 & 0.04 & 0.01 \\ benzenepbutanentirile & 145 & 0.01 & nd & nd \\ sulforapane nitrile & 145 & nd & 0.22 & nd \\
1H-indole, 1-methoxy- & 147 & 0.50 & nd & nd \\ benzene, (isothiocyanatomethyl)- & 149 & 0.11 & 0.41 & 0.01 \\ methyl pentyl disulfide & 150 & 0.23 & 0.01 & nd \\
2,4-decadien, (E,E)- & 152 & 0.67 & 0.07 & 0.01 \\furan, 2-hexyl- & 152 & 0.03 & nd & nd \\ pyrazine, 2-methoxy-3-(1-methylethyl)- & 152 & 0.01 & nd & nd \\
1H-indole-3-acetonitrile & 156 & 0.28 & 1.15 & nd \\ decanal & 156 & 0.18 & 0.07 & 0.01 \\ tetrasulfide, dimethyl & 158 & 4.98 & 3.71 & 0.06 \\ methyl n-octyl sulfide & 160 & 0.08 & 0.01 & nd \\ benzene, (2-isothiocyanatoethyl)- & 163 & 0.52 & 0.43 & nd \\ methyl n-hexyl disulfide & 164 & 0.03 & nd & nd \\ sulforapane & 177 & nd & 0.03 & nd \\ sulfide, methyl 1-methyl-2-butenyl & 178 & 0.01 & nd & nd \\ butanoic acid, 3-hexenyl ester. (E)- & 184 & nd & nd & 0.07 \\ pentasulfide, dimethyl & 190 & 3.61 & 0.41 & nd \\ tetradacean & 198 & 0.13 & 0.28 & nd \\ pentadecane & 212 & 0.06 & 0.04 & nd \\ heptadecane & 240 & 0.13 & 0.22 & nd \\ hexadecanal & 240 & 0.06 & 0.03 & nd \\ heptacosane & 380 & 0.16 & nd & nd \\ sulfurous acid, octadecyl pentyl ester & 404 & 0.16 & 0.81 & nd \\ \hline \hline \end{tabular} s—solvent delay; nd—not detected.  
\end{table} 
Table 2: _Cont._were related to isothicyanates and pyrazines. Isothiocyanates were most effectively isolated by the SAFE method, while pyrazines by the SDE technique. The choice of appropriate extraction technique is of the highest importance in terms of flavor compounds composition and representativeness of the sample aroma. However separation of compounds using the right column for compounds of different character, polarity and belonging to different chemical classes is also important. Analysis of aroma compounds in flavor research is carried out often on two columns of different separation mechanisms to unequivocally resolve and identify the compounds of interest. GC\(\times\)GC provides spatial separation of compounds required in this type of research. The only previous attempt of analysis of aroma-active compounds in broccoli was performed by [PERSON] et al. [8]. Two extraction techniques were compared--SPME and the dynamic headspace sampling on a Tenax trap. Twelve aroma-active compounds were noted, however most of them were not identified.