Estimation of quality of thermally modified beech wood with red heartwood by FT-NIR spectroscopy

The research examines the possibility of predicting the mechanical [modulus of rupture (MOR) and modulus of elasticity (MOE)] and physical (oven-dry and air-dry densities) properties of thermally modified beech wood (Fagus moesica C.) with red heartwood by using FT-NIR spectroscopy and partial least squares regression. Samples of sapwood and red heartwood were treated for 4 h at temperatures of 170, 190, and 210 °C. FT-NIR spectra (100 scans and 4 cm⁻¹) were collected on the radial surface at eight points before and after the thermal modification. Oven-dry and air-dry densities as well as MOR and MOE determined by three-point bending tests were evaluated. Generally, according to the residual prediction deviation (RPD), the majority of the models obtained can be used for preliminary screening (1.5