Tannin and Related Polyphenolic Components from Tropical Tree Species

Abstract

Tannins are widely distributed in tree species such as conifers, eucalypts and legumes. They are divided into two major groups, condensed tannins and hydrolysable tannins. It is well known that condensed tannins undergo some condensation reactions in alkaline media [1, 2]. Thus, it is supposed that condensed tannins partly recondense with lignin fragments during kraft pulping process and consequently affect the pulp properties on recycling uses. It is also well known that tannins are present at very high concentrations in the bark of timber species. Bark is one of the main unused resources, and large quantities of barks are burned up in Japan [3]. Because the regulation of incinerators was made strict in 2002 due to the problem of dioxins, the development of utilization of bark has become a very important issue. In this study, characterization of tannin and related polyphenolic components from the wood and bark of tropical tree species (Eucalyptus camaldulensis, Acacia mangium and A. auriculiformis) was conducted in order to obtain the basic information relating to above matters.