Next Article in Journal
Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks
Next Article in Special Issue
Clonal Variation in the Bark Chemical Properties of Hybrid Aspen: Potential for Added Value Chemicals
Previous Article in Journal
Synthesis, Characterization, Electrochemistry, Photoluminescence and Magnetic Properties of a Dinuclear Erbium(III)-Containing Monolacunary Dawson-Type Tungstophosphate: [{Er(H2O)(CH3COO)(P2W17O61)}2]16−
Previous Article in Special Issue
Value-Added Compound Recovery from Invasive Forest for Biofunctional Applications: Eucalyptus Species as a Case Study
Open AccessArticle

Fate of Antioxidative Compounds within Bark during Storage: A Case of Norway Spruce Logs

1
Natural Resources Institute Finland (Luke), Tietotie 2, FI-02150 Espoo, Finland
2
Natural Resources Institute Finland (Luke), Teknologiakatu 7, FI-67100 Kokkola, Finland
3
Natural Resources Institute Finland (Luke), Kaironiementie 15, FI-39700 Parkano, Finland
4
Natural Resources Institute Finland (Luke), Myllytie 1, FI-31600 Jokioinen, Finland
5
Department of Chemistry, University of Helsinki, PO Box 55, FI-00014 Helsinki, Finland
6
Johan Gadolin Process Chemistry Centre, Åbo Akademi University, FI-20500 Turku, Finland
*
Author to whom correspondence should be addressed.
Academic Editors: Daniel Granato and Petri Kilpeläinen
Molecules 2020, 25(18), 4228; https://doi.org/10.3390/molecules25184228
Received: 31 August 2020 / Revised: 10 September 2020 / Accepted: 11 September 2020 / Published: 15 September 2020
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
Softwood bark is an important by-product of forest industry. Currently, bark is under-utilized and mainly directed for energy production, although it can be extracted with hot water to obtain compounds for value-added use. In Norway spruce (Picea abies [L.] Karst.) bark, condensed tannins and stilbene glycosides are among the compounds that comprise majority of the antioxidative extractives. For developing feasible production chain for softwood bark extractives, knowledge on raw material quality is critical. This study examined the fate of spruce bark tannins and stilbenes during storage treatment with two seasonal replications (i.e., during winter and summer). In the experiment, mature logs were harvested and stored outside. During six-month-storage periods, samples were periodically collected for chemical analysis from both inner and outer bark layers. Additionally, bark extractives were analyzed for antioxidative activities by FRAP, ORAC, and H2O2 scavenging assays. According to the results, stilbenes rapidly degraded during storage, whereas tannins were more stable: only 5–7% of the original stilbene amount and ca. 30–50% of the original amount of condensed tannins were found after 24-week-storage. Summer conditions led to the faster modification of bark chemistry than winter conditions. Changes in antioxidative activity were less pronounced than those of analyzed chemical compounds, indicating that the derivatives of the compounds contribute to the antioxidative activity. The results of the assays showed that, on average, ca. 27% of the original antioxidative capacity remained 24 weeks after the onset of the storage treatment, while a large variation (2–95% of the original capacity remaining) was found between assays, seasons, and bark layers. Inner bark preserved its activities longer than outer bark, and intact bark attached to timber is expected to maintain its activities longer than a debarked one. Thus, to ensure prolonged quality, no debarking before storage is suggested: outer bark protects the inner bark, and debarking enhances the degradation. View Full-Text
Keywords: antioxidant; bark; condensed tannin; forestry side-stream; stilbene; timber antioxidant; bark; condensed tannin; forestry side-stream; stilbene; timber
Show Figures

Figure 1

MDPI and ACS Style

Jyske, T.; Brännström, H.; Sarjala, T.; Hellström, J.; Halmemies, E.; Raitanen, J.-E.; Kaseva, J.; Lagerquist, L.; Eklund, P.; Nurmi, J. Fate of Antioxidative Compounds within Bark during Storage: A Case of Norway Spruce Logs. Molecules 2020, 25, 4228.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop