Effect of Heat Treatment and Cryogenic Treatment on Chemical Components of Rowan (Sorbus torminalis L.) Wood

Abstract

This study investigated the changes in the chemical composition of Rowan (Sorbus torminalis L.) when subjected to heat treatment (HT) and cryogenic treatment (Cr). Rowan wood was treated with HT at two different temperatures (190 and 212 °C) and times (1 and 2 hours). Subsequently, Cr was applied to some of the HT samples and a control sample (Control), creating a total of 8 experimental variations. The content of lignin, holocellulose, alpha-cellulose, ash, and the solubilities of hot water, 1% NaOH, and acetone, were determined. The control and the samples treated with HT and Cr showed differences in most of the investigated properties. For example, the amount of lignin in the samples increased as the HT temperature and time increased (maximum increase of 94.5%). However, Cr was found to limit this increase. Hemicelluloses were the most degraded components during HT, while the degradation of alpha-cellulose was much more limited. In contrast, Cr slightly increased the amounts of hemicelluloses and alpha-cellulose in the heat-treated samples. While HT (212 °C, 2 h) increased the amount of extractives by 2.3 times, Cr caused a decrease in the Control, but greatly reduced this increase in other samples.