Table 8.

The discrimination power of the PEN3 e-nose for distinguishing decay of Aesculus hippocastanum wood blocks, caused by four different species of wood decay fungi, based on PCA by pair-wise comparisons of headspace volatiles. Principal component 1 and principal component 2 explained 65.2% and 28.9%, respectively of the sample variance (σ²) in the data. The data values indicate the decimal fraction overlap of principal component aroma elements that the sample analytes share in common. By definition, a specific analyte shares all principal components when compared against itself and the theoretical decimal fraction overlap is 1.000 for self-comparisons.

Analyte type	Undecayed healthy control	Armillaria mellea	Inonotus dryadeus	Ganoderma lucidum	Heterobasidion annosum
Undecayed healthy control		0.801	0.023	0.529	0.793
Armillaria mellea	0.801		0.824	0.509	0.767
Inonotus dryadeus	0.023	0.824		0.620	0.857
Ganoderma lucidum	0.529	0.509	0.620		0.748
Heterobasidion annosum	0.793	0.767	0.857	0.749