THE ANTIPULPING EFFECT OF THE FLAVANOL OF LARCH HEARTWOOD IN THE SULPHITE COOK

Abstract

In the previous report the authors concluded that the flavanol in larch heartwood has the antipulping effect in sulphite cook owing to the condensation of flavanol and lignin. Some studies were carried out on the antipulping effect of larch heartwood in sulphite cook, especially the behavior of flavanol and the condensation of lignin and flavanol during the cooking. The results are summarized as follows. : (1) The occurrence of the condensation product was not remarkable in the cook of isolated native lignin and flavanol. (2) Quercetin (yield, over 65%) was obtained by the sulphite cooking of isolated flavanol. A large amount of quercetin (yield, over 0.5% based upon the larch heartwood) was also obtained from the waste liquor in normal sulphite cook of larch heartwood. (3) The yellow color of pulp obtained by sulphite cook seems to be due to the presence of quercetin. The result of the determination with ultraviolet absorption spectrum indicates that the content of quercetin in the yellowish pulp is less than 0.12%.