Alkali-soluble hemicelluloses from both rettedlA5 and unrettedh.' jute bark and stem have been studied. However, there has been no report of water-soluble hemicellulose from jute samples. We now report the isolation. fractionation, and structural studies of different polysaccharide fractions obtained by extraction of unretted jute bark and stem (Corchorus capsularis) with water.
The dried and powdered bark and stem from unretted jute (C. capsularis) were first extracted with refluxing aqueous 80% ethanol followed by extraction with hot chloroform (Scheme 1) in order to remove all low-molecular-weight materials, waxes, lipids, etc. Extraction with water at room temperature followed by dialysis gave the dialysable and non-dialysable components. The bark contained -5% and the stem -2% of water-soluble material (Table I). of which the nondialysable part was the highest in amount.
P.c. revealed no free sugar (or lower oligosaccharides) in the dialysable fractions (A from bark and R from stem in Table I). The dialysable fractions contained small proportions of uranic acid residues and hence were not pectins. G.1.c. of the alditol acetates derived from the products of acid hydrolysis showed that the dialysable fractions from both the bark and the stem were rich in glucose, galactose. and mannose. There was also a small proportion of xylose and higher proportions of arabinose and rhamnose.
The non-dialysable fractions (B and S from bark and stem. respectively) were rich in galactose, glucose, and arabinose (Table I) and also contained significant proportions of mannose and rhamnose. Fraction S contained a small proportion of rhamnose and a rather high proportion of xylose, which, together with -10% of uranic acid, indicated that some xylan was extracted from the stem.
The uranic acid content of fraction B was quite high. Carboxyl-reduction' of