Chemical composition of lignin and lipids from tagasaste (Chamaecytisus proliferus spp. palmensis)

Abstract

The chemical characterization of trimming residues of tagasaste (Chamaecytisus proliferus spp. palmensis), a hardy leguminous shrub that has been recently explored for pulp and paper production, was performed with especial emphasis in the composition of lignin and lipophilic extractives. Tagasaste was characterized by a high content of holocellulose (81%) and -cellulose (41%), while having a relatively low lignin content of 18.9%. The analysis of lignin was performed “in situ” by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and showed a composition with a guaiacyl:syringyl (G:S) molar proportion of 38:62 (S/G molar ratio of 1.6) and the absence of p-hydroxyphenyl (H) units. The high S/G ratio, together with its low lignin content makes tagasaste an adequate raw material for pulping. On the other hand, the relatively high acetone extractive content (1.4%) was mostly due to polar compounds and only 0.2% corresponded to lipophilic compounds. The lipophilic compounds, analyzed by GC and GC/MS, were mainly composed of fatty acids, including α-hydroxyfatty acids, and steroid compounds, such as free and conjugated (esters and glycosides) sterols.