Comparison of an Electronic Nose Based on Ultrafast Gas Chromatography, Comprehensive Two-Dimensional Gas Chromatography, and Sensory Evaluation for an Analysis of Type of Whisky

Table 4

Key chemical compounds (variables), which are important for sample discrimination.

Number of variables-column number	Name of the compound	Scotch	Irish	Bourbon
1-1	2-Propanol	+	+	+
2-1	n-Butanol	+	+	+
3-1	Furfural	+	+	+
4-1	Ethyl isovalerate	−	+	+
5-1	Alpha-pinene	+	+	+
6-1	Decanal	+	+	+
7-1	Eugenol	+	+	+
8-1	Geosmin	+	+	+
9-1	Gamma-decalactone	+	+	+
10-1	12-Methyltridecanal	+	+	+
1-2	n-Butanol	+	+	+
2-2	Furfural	+	−	+
3-2	1-Octanol	−	−	+
4-2	Decanal	+	+	+
5-2	2,4-Nonadienal	+	+	+
6-2	Phenylethyl acetate	+	+	+
7-2	(E,E)-2,3-Decadienal	+	+	+
8-2	4-Vinylguaiacol	−	−	+
9-2	Geosmin	+	+	+
10-2	Gamma-nonalactone	−	−	+
11-2	Gamma-decalatone	+	+	+

“+” means that the compound was considered as variable for the chosen group.
“−” means that the compound was not considered as variable for the chosen group.