A1 Journal article (refereed)
The effect of thermal drying on the contents of condensed tannins and stilbenes in Norway spruce (Picea abies [L.] Karst.) sawmill bark (2021)
Jylhä, P., Halmemies, E., Hellström, J., Hujala, M., Kilpeläinen, P., & Brännström, H. (2021). The effect of thermal drying on the contents of condensed tannins and stilbenes in Norway spruce (Picea abies [L.] Karst.) sawmill bark. Industrial Crops and Products, 173, Article 114090. https://doi.org/10.1016/j.indcrop.2021.114090
JYU authors or editors
Publication details
All authors or editors: Jylhä, Paula; Halmemies, Eelis; Hellström, Jarkko; Hujala, Maija; Kilpeläinen, Petri; Brännström, Hanna
Journal or series: Industrial Crops and Products
ISSN: 0926-6690
eISSN: 1872-633X
Publication year: 2021
Volume: 173
Article number: 114090
Publisher: Elsevier BV
Publication country: Netherlands
Publication language: English
DOI: https://doi.org/10.1016/j.indcrop.2021.114090
Publication open access: Openly available
Publication channel open access: Partially open access channel
Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/78371
Abstract
The initial CT content of 35–36 mg g−1 in dry bark material declined to 25–31 mg g-1 in 28–34 h. The average degree of polymerisation (DP) decreased slightly, and the relative proportion of prodelphinidins in CTs increased significantly in the 60 and 70 °C schemes. The proportion of A-type linkages slightly increased with the increase in drying temperature. The initial mean stilbene contents varied from 19 mg g−1 to 22 mg g−1 in dry bark mass. Isorhapontin was the major stilbene constituent, with a proportion of 45–49 % of the total stilbenes. Stilbene losses of up to 60 % were detected during the drying processes. In 10 h, for example, 36–43 % of total stilbenes were lost. Degradation activities by enzymes released from the bark and oxidative reactions after crushing at the debarking phase were concluded to be the primary mode of degradation. The results indicate that bark CT content can be preserved at a moderate temperature not exceeding 50 °C, but the degradation of CTs may affect their suitability for various applications. Sufficient stilbene content for industrial processes is unlikely to be maintainable through thermal drying. The permanence of the post-drying extractives content should be assessed based on a practical-scale storage experiment using bark dried to varying moisture contents.
Keywords: biomass (industry); bark; Norway spruce; drying; degradation; naturally occurring substances; tannins; stilbenes
Free keywords: condensed tannins; stilbenes; gravimetric extractives; thermal drying; degradation
Contributing organizations
Ministry reporting: Yes
Reporting Year: 2021
JUFO rating: 2