Hot water extraction of Norway spruce (Picea abies [Karst.]) bark: analyses of the influence of bark aging and process parameters on the extract composition.

Bianchi, Sauro; Koch, Gerald; Janzon, Ron; Mayer, Ingo; Saake, Bodo; Pichelin, Frédéric (2016). Hot water extraction of Norway spruce (Picea abies [Karst.]) bark: analyses of the influence of bark aging and process parameters on the extract composition. Holzforschung, 70(7), pp. 619-631. De Gruyter 10.1515/hf-2015-0160

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The hot water (HW) extraction of Norway spruce (Picea abies [Karst.]) delivers condensed tannins and considerable amounts of other compounds. Yield and composition of the HW extracts were investigated as a function of natural weathering for up to 15 months. Total phenol monomers and oligomers were detected by Folin-Ciocaltau assay after fractionation by solid phase extraction (SPE). Procyanidins (PC) were determined by HPLC-UV after acid thiolysis and carbohydrates by HPLC combined with acid hydrolysis. Topochemistry of the bark before and after extraction was investigated by UV- microspectrometry (UMSP) and non-extractable PC analyzed by direct thiolysis on the bark. The influence of the parameters on the yield and composition of the extracts were evaluated, such as the extraction temperature, time and the addition of sodium sulfate and urea. Prolonged weathering resulted in a considerable decrease of the total extraction yield, partly because of leaching of phenolic monomers, mono- and oligosaccharides. The yield of phenolic oligomers also decreased at a moderate rate, while the yield of polysaccharides (pectins) was almost stable. Nonextractable and non-leachable compounds deposited in the cell lumens represent the majority of the phenolic extractives in spruce bark. Sequential extractions performed at increasing temperature proved to be a suitable method for the recovery of tannin-rich extracts.

Item Type:

Journal Article (Original Article)

Division/Institute:

School of Architecture, Wood and Civil Engineering

Name:

Bianchi, Sauro0000-0002-6979-3622;
Koch, Gerald;
Janzon, Ron;
Mayer, Ingo;
Saake, Bodo and
Pichelin, Frédéric0000-0003-3856-6707

ISSN:

1437-434X

Publisher:

De Gruyter

Language:

English

Submitter:

Admin import user

Date Deposited:

17 Dec 2019 10:40

Last Modified:

18 Dec 2020 13:28

Publisher DOI:

10.1515/hf-2015-0160

Related URLs:

ARBOR DOI:

10.24451/arbor.6118

URI:

https://arbor.bfh.ch/id/eprint/6118

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