Tannins extraction from Pinus pinaster and Acacia dealbata bark with applications in the industry

Abstract

The use of wood waste is considered a valuable resource and a market opportunity for new products that society and industry can employ. In this context, it seems important to consider the use of the bark of two species that are found in large quantities within the extensive forest area of Galicia (north-western Spain). These species are widely used in industrial processes in which a large amount of waste is generated, mainly bark. In this work, we extracted the tannins from the bark of Pinus pinaster and Acacia dealbata, and we studied the yields obtained according to three variables: the extraction method applied, soxhlet and in natural conditions with temperature and agitation; the particle size of the samples; and the two solvents used, ethanol and distilled water. The chemical properties of the extracts were also analysed. The yields obtained ranged from 3.6 to 25.8 wt% for P. pinaster, and from 5.2 to 29.5 wt% for A. dealbata. Phenol and anthocyanin content ranged from 217.8 to 873. 2 mg/g extract for P. pinaster, and from 77.3 to 820 mg/g extract for A. dealbata. Our results demonstrate that the differences in the extracts content depending on the method and particle size show different features of the antioxidant capacity.