Multiscale assessment of the heterogeneity of scutched flax fibers

The industrial process of extracting flax fibers from a plant ( Linum usitatissimum L.), which involves a combination of retting and scutching, could lead to matter heterogeneity within individual roll bales. Although many studies have investigated the variability of flax fiber compositions and properties as functions of various factors throughout the value chain, no researchers have focused on long-fiber bale heterogeneity and its impact on quality. In this work, five batches were empirically identified based on visual and textural criteria, and were subsequently characterized. The study of their differences and similarities using a combination of physicochemical methods allowed them to be classified into several groups, depending on the criteria measured and the structural scale. Thus, variations in surface composition were related to the presence of external tissue residues and microbial biomass but were not related to the measured polysaccharide composition. Additionally, the technical fibers displayed different mechanical and hygroscopic properties, which could be distributed within 2-4 groups, independent of color and surface composition criteria. This study is a first step in determining fiber heterogeneity, which constitutes a global quality assessment for the further application of flax fibers.