Steaming-caused chemical changes of sugi (Cryptomeria japonica) wood monitored by NIR spectroscopy

Abstract

Abstract. Mahdiyanti SH, Tsuchikawa S, Mitsui K, Tolvaj L. 2020. Steaming-caused chemical changes of sugi (Cryptomeria japonica) wood monitored by NIR spectroscopy. Asian J For 4: 6-9. Steaming is a common method to change the color of wood to enhance attractiveness. This study aimed to investigate time-dependence of chemical changes of sugi (Cryptomeria japonica D. Don) wood steamed with temperature of 90 and 110°C and monitored up to 20 days using NIR spectroscopy. The difference spectrum method was applied to find the absorption increases and decreases. Before the subtraction, the spectra were normalized to one unit at 1739 nm to eliminate the parallel shift of the spectra. The results showed that steam-induced chemical changes in the wavelength range of 1300-2100 nm were related to the absorption of water and the absorption of extractives, especially phenolic contents. These chemical changes were suspected to be strongly related to color changes in steamed wood. Longer duration of steaming caused phenolic compounds to change into similar contents in all wood tissues, which cause their color to change more uniformly. Steaming caused a water bounding capacity loss of the cell wall. This change was much faster at 110°C than at 90°C.