BLACKCURRENT STEMS - A NOVEL NON-TREE FIBER FOR THE PRODUCTION OF PULP AND PAPER

Debarked sterns of blackcurrant (Ribes nigrum L.; cv. Ben alder) were hammer-milled and extracted with water (70 degrees) and diethyl ether. The residue was subjected to alkaline extractions with increasing con centrations of aqueous NaOH and chlorite delignification. Analysis of the neutral sugar, lignin and uronic acid contents of the residues and extracts indicated that blackcurrant stem should be considered as a t ypical hardwood. The 0.1 M and 1.0M NaOH extracts provided both hemice llulose (H/C) A and a H/C B fraction, while the 4.5M NaOH extract only yielded the latter. The principal polysaccharides in all these fracti ons mere glucuronoxylans. These were present at higher concentrations in each H/C B fraction than the corresponding H/C A fraction. Other po lysaccharides present mere arabinoglucuronoxylan, glucomannan, mannan and galactan. The extracted lignin contents were greatest in the H/C A fractions. Tile effects of chlorite delignification mere largely conf ined to a reduction in the residual lignin content by c. 94%. This was confirmed by FT-IR spectroscopy. Four distinct cell types were found in blackcurrent stems; tracheids, libriform fibres, vessel elements an d ray parenchyma cells, These cell types are also present in a typical hardwood, although their dimensions were smaller. The results of the study suggest that blackcurrant stem fibres ha-e the potential to he u sed along with existing mood-based fibres in the production of pulp fo r paper manufacture.