Willow bark is a rich source of heterogeneous polyphenolic compounds and a potential feedstock for biorefinery processes aiming at chemicals and fiber production. Here, mild hot water treatment of willow hybrid Karin was studied to find a practical means of isolating its non-cell-wall components for their utilization in a willow biorefinery proposed to aid valorization of the willow biomass. A short aqueous treatment of the bark at 80 °C liberated the extract in >20% yield under unpressurized conditions. The extract was characterized using mainly gas chromatography-mass spectrometry and one- and two-dimensional NMR techniques. Authentic analytes were applied to confirm the identification and quantification of the main components that were picein, (+)-catechin, triandrin, glucose, and fructose. Fructose was converted into 5-hydroxymethylfurfural in an acidic treatment which led to its condensation with the phenolic components and formation of a recalcitrant precipitate that should be avoided. © 2018 American Chemical Society.
- Willow bark
Dou, J., Koivisto, J., Dharshana , P., Kögler, M., Xu, C., Willför, S., Ralph, J., Vuorinen, T., & Mobley, J. K. (2018). Characteristics of Hot Water Extracts from the Bark of Cultivated Willow (Salix sp.). ACS Sustainable Chemistry & Engineering, 6(4), 5566–5573. https://doi.org/10.1021/acssuschemeng.8b00498