Extraction of bioactive compounds using twin-screw extrusion : comparison between two hemp coproducts

Overview & Synopsis

Biomass represents an important source for the production of multiple products including high-value chemicals. In this context, different lignocellulosic residues have been explored for the extraction of aromatic monomers. It includes ultrasonic extraction, refluxing extraction, alkaline hydrolysis and accelerated solvent extraction [1]. Aromatic monomers could be used for food, cosmetics and pharmaceutical applications. Hemp (Cannabis sativa L.) is an annual herbaceous plant. The natural fractions resulting from the industrial transformation of hemp are hemp fiber and its two co-products hemp wood and hemp dust. 5,500 tons of hemp wood and 2,300 tons of hemp dust are produced from the transformation of 10,000 tons of raw material. Hemp fiber is largely used in paper, for clothing and for the manufacture and reinforcing of every type of composites. Hemp wood and dust are used in gardening, stockbreeding and as litter for animals because of their high absorption capacity. Developing higher value-added applications from these natural by-products would secure the hemp sector. As these coproducts are rich in lignin, the extraction of aromatic monomers in particular ferulic and coumaric acids can represent an interesting valorization for hemp wood and dust. Characterization of this two coproducts using Van Soest method provided a value of 86.8% in lignocellulosic materials (50.6% cellulose, 18.2% hemicelluloses and 18.0% lignin) for hemp wood compared to 61.7% in lignocellulosic materials (43.9% cellulose, 10.7% hemicelluloses and 7.0% lignin) for hemp dust. Total phenolic compounds and aromatic monomers were evaluated using Folin-Ciocalteu method and HPLC-UV-vis analysis, respectively. In this work, twin-screw extrusion method has been developed to extract aromatic monomers in hemp wood and dust. Twin-screw extrusion is a continuous extraction system using thermo-mechano-chemical effects [2, 3]. The influence of experimental conditions, such as screw profile, solvent, liquid/solid ratio and temperature on extraction efficiency was studied for hemp wood and dust. High yields of aromatic compounds were obtained at low temperature and liquid/solid ratio using alkaline ethanol. Twin-screw extrusion gives promising results to obtain aromatic monomers of interest from hemp coproducts.