Characterization of technological properties of matá-matá wood (Eschweilera coriacea [DC.] S.A. Mori, E. odora Poepp. [Miers] and E. truncata A.C. Sm.) by Near Infrared Spectroscopy

Abstract: The aim of this study was to determine the technological properties (chemical, mechanical and physical) of Eschweilera sp. woods using near infrared spectroscopy (NIRS). NIR spectroscopy proved to be efficient for chemical analysis (extractives, lignin and carbohydrates) and physical-mechanical testing (moisture content, basic density - BD, modulus of elasticity - MOE and modulus of rupture - MOR) of wood, providing a powerful tool for use in sustainable forest management activities in the Amazon. Wood samples from three trees of each Eschweilera species were collected from the Experimental Station of Tropical Forestry/INPA/Brazil. Specimens were extracted from the cross-sectional area (20 × 20 × 30 mm) in the direction sapwood-heartwood. NIR spectra (4.000-10.000 cm-1) were then obtained from the samples (moisture 12%) using Fourier-transform spectrometry. The Partial Least Squares (PLS) regression prediction models for the chemical, mechanical and physical properties of Amazonian woods were used for quantification. The results for total extractives (both in toluene and ethanol) and hot water solubility showed a maximum extractive concentration of 7.66% and 3.13% for E. odora (yellow mata-mata), including several compounds with low molecular weight, such as resins, gums, terpenes, alkaloids, flavonoids, and tannins. The highest concentration of phenolic substances (tannins) was found in E. Truncata (black mata-mata, 10.00%). The macrocomponents (primary metabolism) of Eschweilera species were in the range of 44.20-46.33% for cellulose and 28.89-31.21% for lignin. Mineral compounds (ash) were quantified in concentrations < 0.70%. The predictive results for the physical and mechanical properties of mata-mata wood are in the standard range for tropical woods. The higher calorific value (HCV) varied from 4.993-5.033 cal g-1 and the BD from 0.78-0.88 g m-3. Regarding moisture, the highest content was observed in E. truncata (13.46%). Values for mechanical resistance were in the range of 14,253-17,447 MPa for MOE and 146.04-175.73 MPa for MOR, with the greatest strength attributed to E. truncata wood. The values obtained for the wood technological properties of E. coriacea (white mata-mata), E. odora (yellow mata-mata) and E. truncata (black mata-mata) were compatible with those obtained by destructive determination of tropical species and also for other species of the genus Eschweilera.