Beaugrand, Johnny
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Item type:Publication, Decortication and separation of wet or dry hemp stems - What difference does it make?Hemp decortication, a crucial step in fibre processing, traditionally uses dry stems with low water content. However, processing hemp in a wet state has gained attention as an alternative method, especially with the development of harvesting techniques that decorticate the stems directly in the field. We investigated the effects of stems' initial moisture content on hemp fibre functional quality using freshly harvested hemp stems from different varieties. The stems were subjected to wet and dry decortication processes to evaluate potential differences in fibre damage and biochemical composition. Our experiments involved utilising a laboratory roller-breaking device for the initial decortication of the fresh hemp stems in their wet state and subsequent mechanical separation to assess fibre bundle integrity. As a comparison, we performed the same procedure on stems that were first dried before processing. We found that wet processing resulted in higher lignin levels in the fibre bundles, containing a higher quantity of middle lamellas, where lignin or another biochemical marker is typically found. The analysis revealed significant damage to the fibre bundles during the wet decortication process, as evidenced by the destruction and fibrillation of the bundles, clearly visible in scanning electron microscope (SEM) images. Interestingly, the dry conditions led to more fractures between fibres, while wet conditions allowed fractures between bundles and the surrounding histological structure. These findings suggest that wet processing may render the material more ductile, resulting in more complex crack modes, including combined torsion and delamination, leading to fracture paths passing through the cross-section of individual fibres. Consequently, the fibre bundles from wet processing may exhibit more structural damage than dry-processed fibre bundles. In conclusion, our study's findings are important as they highlight the severe damage that can occur to the fibre bundles during the decortication and separation of freshly harvested, moist hemp stems.journal articleBand:22366 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Determination of a suitable molar absorption coefficient (ε) for lignin analysis of fibrous plants using the CASA method(Elsevier BV, 2025-05); Boizot, NathalieIn this study, the benchmarking and applicability of the CASA method for the analysis of fibrous plants, such as flax, hemp, and jute, is evaluated. Lignin is a phenolic biopolymer present in plant cell walls and is composed of three primary monomeric units, designated G, S, and H. Various factors, such as the genetic variability, influence the relative proportions of these units in plant samples. Recently, the cysteine-assisted sulfuric acid (CASA) method has been introduced as a rapid method for the quantification of lignin in wood samples. The aim of this study is to establish a suitable molar absorption coefficient (ε, L·g−1·cm−1) to adapt the CASA method for use with annual plant fibers. This investigation was motivated by the technical advantages of the CASA method, including higher throughput, lower reaction temperatures, and ecological benefits due to the absence of carcinogenic, mutagenic, or reprotoxic (CMR) substances and the need for minimal sample quantities. In this method, lignin solubilization is facilitated by cysteine, which is an amino acid that enhances the reaction kinetics, using a one-hour incubation period. However, as with any spectrophotometric technique, the CASA method depends on a molar absorption coefficient (ε) that varies according to the ratio of the aromatic units within the polymer. To evaluate the suitability of CASA for quantifying lignin in economically significant plant fibers, we investigate the impact of the unit ratios on the accuracy of ε. The results are compared with those of two widely recognized lignin analytical methods: the Klason method, which is a gravimetric reference method, and the acetyl bromide soluble lignin method, which is the most commonly used spectrophotometric approach. The final ε obtained in this study reveals a relative difference in lignin content ranging from −8 % to +9 % based on a comparison between the CASA and Klason methods across different industrial hemp varieties. Using known G:S ratios in annual fibrous plants, ε can be estimated from our results.journal articleBand:308Heft:116