Detection of the Aromatic Profile of Thermally Modified Wood Species

Thermo-modified wood material for indoor use produces chemical compounds that significantly affect indoor environmental issues and human health. The thermal modification method influences the chemical properties of wood. Our study aimed to evaluate the effect of thermal modification on the aromatic profile of seven wood species namely Cedrus deodara Roxb, Pinus laricio L, Alnus cordata L, Populus nigra L, Fagus sylvatica L (thermo-modified at a temperature of 200 °C), Quercus Cerris L, and Castanea sativa Mill (thermo-modified at a temperature of 170 °C). An olfactory machine so-called PEN 3 AIRSENSE electronic nose (e-nose) consisting of 10 doped semi-conductive metal-oxide gas sensors (MOS) was used for this purpose. Wood planks were thermally modified and cut into small wood blocks for autoclave sterilization to obtain the final extracts in water solution for olfactory detection. Principal component analysis (PCA) and linear discriminant analysis (LDA) provided an evaluation of the ability of the e-nose sensor array to associate a response pattern with the corresponding class of compounds. The loadings analysis was used to identify the sensors responsible for discrimination in the current pattern file. Results showed that the W5S sensor, with its characteristic for react to nitrogen oxides (NO2), explained most of the variance attributed to the odor of both thermo-modified and unmodified woods.