Characterization of non-cellulosic glucans in Eucalyptus globulus Labill. wood and kraft pulp

resumo

The amount of non-cellulosic glucans in Eucalyptus globulus wood (approx. 4.5%) was assessed by extraction of sawdust with a 0.5 M NaOH solution at 90-120 degrees C and the structural features were elucidated in a glucan-enriched polysaccharide fraction isolated by hot water extraction (120 degrees C, 2 h). Isolated soluble glucans were characterized by wet chemistry methods and a set of 1 D and 2D NMR techniques. The major proportion of glucans consisted of amylose (20%) and annylopectin (80%), although a small proportion of beta-(1 -> 3)-glucan (<0.2% on wood weight) was also detected. Although glucans are easily removed in the initial phase of kraft pulping, notable amounts were found in unbleached pulp and it was supposed that in the final stage of kraft pulping a fraction of a-glucan is precipitated onto the fiber surface and contributes to the pulp yield.

palavras-chave

POLYSACCHARIDES; HEMICELLULOSE; RETENTION

categoria

Forestry; Materials Science

autores

Lisboa, SA; Evtuguin, DV; Neto, CP

nossos autores

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