Douglas bark dry fractionation for polyphenols isolation: From forestry waste to added value products

Abstract

In order to isolate polyphenols from Douglas fir outer bark, this latter was mechanically fractionated by means of knife and ball millings. The sieving of the resulting powder gave rise to a set of fractions with different particle sizes and shapes. The particles ranging from 0.56 to 0.16 mm size were mainly composed of tannins (46%) while, taxifolin was located in the coarser fraction (83%) with particles size above 1 mm. The isolated phenolic compounds are suitable of upgrading to higher value products.