Loblolly pine wood between the ages of 5-35 was refined into medium density fiberboard furnish at steam pressures from 2 to 18 bar. The effect of age and processing conditions on the properties of the fibers was assessed by wet chemical analyses, Near Infrared Spectroscopy (NIR) and powder X-ray diffraction (XRD). In general, the percentages of extractives and glucose increased, while the xylose, galactose, and mannose decreased with increasing refining pressure. There were no consistent changes in chemical composition of the refined fibers as a function of the age of the wood. The crystallinity of the refined fibers increased with both age and refining pressure. The spectroscopic and XRD data were analyzed using multivariate statistical methods, indicating a strong relationship between the spectral patterns and refining pressure
