Flax fibers: assessing the non-cellulosic polysaccharides and an approach to supramolecular design of the cell wall

Abstract

Due to their particular tensile properties and composition, flax cellulosic fibres are widely used in various applications and are important in the stem architecture, as a source of mechanical support. Here, we have examined how various chemical extractions of cell-wall polysaccharides might improve our understanding of the structure and composition of these fibres. A set of chemical extractions, which had previously been independently studied on fibres of different origins and by different laboratories, was run on the same batch of technical fibres, variety Eden, and the released non-cellulosic polysaccharides were analyzed in terms of sugar composition and size exclusion chromatography. No single-step protocol was able to extract all the non-cellulosic polysaccharides estimated to be in the range of 130–140 mg per g of dry fibres. The major polymers consisted of rhamnogalacturonan and glucomannan, while the minor ones were xyloglucan and xylan. Several types of stepwise extractions helped to elucidate the subfractions of each polymer that are differently retained within cell wall. From our data, we have pointed out a new model which might help to approach the supramolecular design of the flax cellulosic fibres and, afterwards, the relationships between their chemical composition and their mechanical properties.