Influence of thermal modification and extraction techniques on yield, antioxidant capacity and phytochemical profile of chestnut (Castanea sativa Mill.) wood

Numerous investigations on the antioxidant properties of different plant tissue extracts are available in literature, but few studies on the effect of thermally modified wood on secondary metabolites were carried out up to now. This study highlights the influence of the thermal modification of Castanea sativa Mill. wood on total content of antioxidant compounds and consequently on its antioxidant activity. In addition, a chemical profile by Gas Chromatography-Mass Spectrometry (GC-MS) of the extractives was carried out. Wood of chestnut, thermally modified at 180 °C for 3 h, was used to obtain wood meal which was subjected to different extraction techniques, as maceration extraction (ME), ultrasound assisted extraction (UAE) and accelerated solvent extraction (ASE). The total content of principal antioxidant compounds, such as polyphenols, flavonoids and tannins, as well as the evaluation of antioxidant capacity by using different in vitro assays were determined. Relative Antioxidant Capacity Index (RACI), which is used to compare all antioxidant parameters, has also been applied. The study demonstrated a positive influence on chemical compounds present in C. sativa Mill wood originating from the thermal modification process. Thus, is possible to consider thermal modification as a promising strategy to improve the antioxidant activity of chestnut wood extractives.