Comparing chemical composition and lignin structure of Miscanthus x giganteus and Miscanthus nagara harvested in autumn and spring and separated into stems and leaves

Abstract

Miscanthus crops possess attractive properties such as high photosynthesis yield and carbon fixation rate. Moreover, M. nagara, shows good frost tolerance. Monolignol ratio and most abundant linkages of the isolated lignins have been identified.

Lignins Isolated via Catalyst-free Organosolv Pulping from Miscanthus x giganteus, M. sinensis, M. robustus and M. nagara: A Comparative Study

“…The stem and mixture lignins, for example, have a relatively high share of approximately 20 % or more (peak value for M. sinensis Sin2 with over 30 %). In the leaf-derived lignins, the proportions are significantly lower on average.Results presented here for stem versus leaf-based lignins are in good agreement with previously published studies including further data such as crop yields, chemical composition of the biomasses, ash contents[30,31,43,44] and calorific values[43]. If the highest possible lignin content is desired, stem samples should be chosen, specifically from the M. x giganteus genotype, which revealed lignin contents up to 27 %.From a European agricultural perspective, the genotype M. nagara (NagG10) might be the most suitable for further uses due to its high crop yield and winter hardiness.…”

“…In the following, the organosolv process, the determination of the chemical composition according to the NREL procedure as well as the HSQC NMR analyses are described. Further details could be found in the corresponding studies reported by our group [30,31,43,44].…”

“…The Miscanthus samples were ground to a particle size of less than 0.5 mm using a ball mill (Fritsch model Pulverisette 6) and a sieving machine, (Retsch model AS 200 basic). The digestion method used was previously published in detail [30]. For this purpose, 50 g of the biomass samples were mixed with 500 mL of 80% ethanol solution in a Parr pressure reactor.…”

“…Spectra of the aromatic region can be assigned to the lignin monomer building blocks (H, G, S), whereas the signals of the non-aromatic mainly indicate the linkage patterns (A, B, C, D) within the lignin(Figure 8)[30,31,43].…”

Lignins Isolated via Catalyst-Free Organosolv Pulping from Miscanthus x giganteus, M. sinensis, M. robustus and M. nagara: A Comparative Study

“…Besides crop and cell wall composition, focus of current research is also directed toward Miscanthus-derived lignins and their detailed 3D structure, including the monolignol ratio (G, H, S, Figure 1) and corresponding interunit linkages (Figures 2-4) [27][28][29][30][31]. Both the G/H/S ratio and the linkages strongly depend on the biomass origin (crop genotype) and biomass treatment (pulping) method for lignin isolation.…”