Department of Bioproducts and Biosystems

Wood extractives

The Wood Extractives group is headed by Academy Research Fellow Jinze Dou. The group’s research interests focus on fundamental understanding of the challenges posed by wood extractives, particularly in the areas of the wood yard and the fiber line of pulp mills, including pre-treatment techniques for “pulping” of the bark, characterization and (bio)chemical control of pitch/stickies deposits, and the functionalization of extractives for added-value biochemicals.
Color photo of a hat made of fine bark strips featuring a red hatband and a fiber-constructed letter "A"
Handcraft: Tapani Vuorinen, Photo: Valeria Azovskaya | Aalto University

Research topics

  • Bark structure and chemistry
  • Role of the extractives in formation of pitch/stickies deposits
  • Extractives functionalization
Pitch deposits in the bleach plant process pipe
Pitch deposits in the bleach plant process pipe. Photo: Jinze Dou

Ongoing research projects

Understanding the Role of Wood Extractives in Formation of Pitch Deposits (WEPitch)
Control of wood extractives has a vital role in closing the water loops in pulp mills, thus helping the pulp and paper industry to achieve the “zero effluent” target. As there is no efficient way to control and remove them from the fiber line, extractives can be a technical challenge. Wood extractives cause a lot of effort to the process and can create serious problems, because they flow and accumulate in water, forming pitch deposits. The extractives retained in the pulps may adversely affect the physiochemical properties of the products. Efficient removal of pitch deposits from the fiber line is currently hampered by the lack of knowledge of their full chemical characteristics and the exact formation mechanism. The Industry- and FinnCERES- jointly funded project WEPitch (2024-2028) is designed to find ways to gain essential knowledge to understand, prevent and control deposit formation and improve the overall operation, revenue and quality performance of the pulp and paper mill.

Related publication:
Dou, J.*; Niemelä, Klaus*; Haatainen, Tiina; Tervola, Pekka; Vehmaa Janne*. Investigation of pitch deposits throughout the fibre line of softwood pulp mills. (2023-03-28) J. Cleaner Prod. 405, 136940.

Color photograph of a person in the forest wearing a lab coat and blue gloves pouring brown liquid from a glass tube into a glass flask, next to a container of bark/wood chips and a brown liquid being filtered into another glass flask
Photo: Eeva Suorlahti | Aalto University CHEMARTS

Stability enhancement of softwood (sawdust wood and bark) stilbene through chemical functionalization as ultra stable UV-filters in sunscreen (FACE+)

Trans-stilbenes can be isomerized to their cis-isomers under sunlight, and the cis-isomers are prone to undergo a Mallory reaction yielding polycyclic aromatic hydrocarbons. This preference is very hard to overcome as it is strictly under orbital symmetry control. The Academy of Finland Research Fellow project (2023–2027) will focus on functionalizing the recovered stilbene from pine wood sawdust and spruce bark as ultra-stable UV-filter alternatives for sunscreen. This may improve the stilbene stability 1000-fold without losing its UV-absorbing activity. These materials are today merely burned for energy, but when using them to added-value chemicals, it could allow more incomes for the Finnish forest owners and industry.

Related publications:

Dou, J.*; Multia, Evgen; Dong, Xinyue; Wang, Lei*; Vuorinen, Tapani. Valorization of long-neglected spruce bark and bark-press effluents through integrated utilization of stilbenoids and pectin. (2023) Chem. Eng. J.

Dou, J.*; Sui, M.; Malinen, K.; Pesonen, T.; Isohanni, T.; Vuorinen, T. Spruce Bark Stilbenes as a Nature-inspired Sun Blocker for Sunscreens. (2022-03-02) Green Chem. 24, 2962−2974.

News and events

  • Hao Xi and Ali Muhammad join the lab for master thesis project in February 2024
  • Noora Karvonen, Mitja Heikkilä, and Vera Haag join the lab for bachelor thesis project in Jan 2024
  • New project "WEPitch", jointly funded by Industry and FinnCERES, started in March 2024
  • Wajeeha Munib joins the lab in December 2023
  • New project "FACE+", funded by Academy of Finland, started in September 2023


Dr. Dou teaches the lecture ‘‘Wood Extractives in Fiberline’’ as part of the course ‘‘CHEM-E1150 - Biomass Pretreatment and Fractionation’’, organized next time in Jan-March 2024. The main target of the lecture is to focus on the reactivity of wood extractives in fiberline. Particularly, the students are expected to know the reactivity of major category of wood extractives (fats, resin acids, tall oil, turpentines) in the fractionation process (i.e. cooking and bleaching).

Previous research project

Fractionation of willow bark for combined production of extracts and fiber bundles

Color photo of willow tree bark
Photo: Aalto University

This project, mainly funded by Finnish Cultural Foundation (2016-2019) and FinnCERES (2019-2021), provides a general, integrative study on the morphology and chemistry of willow wood and bark and its fractionation into hot water extract, fiber bundles, fibers and fibrils. Potentially interesting research approaches and gaps in our current knowledge are identified and discussed on the way towards full exploitation of the value of the bark as a source fibers and extracts.

Related publications

Dou, J.*; Wang, Jincheng; Hietala, Sami; Vuorinen, Tapani*; Zhao, Jian. Structural Features of Lignin-Hemicellulose-Pectin (LHP) Orchestrate the Tailored Microbial Consortium for potential in Bark Biorefinery. (2023) Green Chem.

Dou, J.*; Kögler, Martin; Kesari, Kavindra; Pitkänen, Leena; Vuorinen, Tapani. Seasonal dynamics in structural characteristics within bark stems of cultivated willow (Salix sp.) by NMR and time-gated Raman spectroscopy. (2023-01-26) Green Chem. 25, 1908−1919.

Dou, J.*; Wang, J.; Zhao, J.*; Vuorinen, T. Tailor-made Enzyme Consortium Segregating Sclerenchyma Fibre Bundles from Willow Bark. (2022-02-23) Green Chem. 24, 2576−2587.

Dou, J.*; Chandgude, V.; Vuorinen, T.*; Bankar, S.; Hietala, S.; Huy, L. Enhancing Biobutanol Production from Biomass Willow by Pre-removal of Water Extracts or Bark. (2021-10-22) J. Cleaner Prod.327, 129432.

Dou, J.*; Heinonen, J.; Xu, C.; Vuorinen, T.; Sainio, T.* Chromatographic purification of the natural phytochemicals from willow bark water extracts. (2020-12-26) Sep. Purif. Technol. 261, 118247.

Dou, J.; Kim, H.; Li, Y.; Padmakshan, D.; Yue, F.; Ralph J.; Vuorinen, T*. Structural characterization of lignins from willow bark and wood. (2018-06-22) J. Agric. Food Chem. 66, 7294−7300.

Dou, J.; Galvis, L.; Holopainen-Mantila, U.; Reza, M.; Tamminen, T.; Vuorinen, T*. Morphology and Overall Chemical Characterization of Willow (Salix sp.) Inner Bark and Wood: Toward Controlled Deconstruction of Willow Biomass. (2016-06-06) ACS Sustainable Chem. Eng. 4, 3871–3876.

Group members

 Jinze Dou

Jinze Dou

Academy Research Fellow
 Wajeeha Munib

Wajeeha Munib

Research assistant (preparing for doctoral thesis work)

Hao Xi

Master's thesis worker
Academy Research Fellow Jinze Dou.

Research Council of Finland Fellow Dr. Jinze Dou

Dr. Dou obtained his PhD in the field of Bioproduct Technology under the supervision of Prof. Tapani Vuorinen from Aalto University in 2018, though part of his research was carried out at the University of Wisconsin Madison, USA, under the supervision of Prof. John Ralph. During his postdoctoral research work at Aalto, he had long visits to the University of Aveiro, Portugal (Prof. Dmitry Evtyuguin), Lappeenranta-Lahti University of Technology in Finland (Prof. Tuomo Sainio) and Shandong University, China (Prof. Jian Zhao). In addition to these academic steps, he also has industrial experience working as a research scientist at Andritz Oy (January 2022-August 2023). The Research Council of Finland (formerly known as the Academy of Finland) awarded Dou the Academy Research Fellowship for 2023-2027.

Munib Wajeeha

Research Assistant (preparing for doctoral thesis work) Wajeeha Munib

Munib is a doctoral student specializing in the stability enhancement of stilbenes from pine wood sawdust and spruce bark through chemical functionalization. She has a foundational Master's degree in organic chemistry and a robust research background in organic synthesis. Her current doctoral research is focused on developing ultra-stable UV filters for sunscreen applications, leveraging the inherent properties of softwood sawdust and spruce bark extractive stilbenes. Areas of interest include: wood extractives, controlled stereo chemical reactions, and chemical functionalization of stilbenes for macrocyclization. 

Photo of student Hao Xi wearing a grey shirt looking directly into the camera

Research Assistant Hao Xi

Hao is an aspiring master’s student at Aalto University, focusing on biomass refining. His academic journey is enriched by practical experiences, such as internships at Metsä Board in 2021 and BASF in 2023. An academic exchange at the Technical University of Denmark broadened his horizons. Currently, he is advancing his Master’s thesis under the guidance of Dr. Jinze Dou. With a passion for sustainability, Hao’s goal is to apply his knowledge to initiatives that have a significant and positive environmental impact.

Color photo of student Muhammad Ali smiling into the camera wearing a dark suit jacket and grey shirt

Master's thesis worker Muhammad Ali

Ali contributes as a Master's thesis worker on the characterization of extractive-free de-inked pulp. His focus is to integrate the surface chemistry and full chemistry data of de-inked pulp. The work will offer a holistic understanding of the chemical characteristics of extractive-free de-inked pulp.

Latest publications

Characterization of crude extracts from willow barks and their performance as proanthocyanidin -based coagulants in water treatment

Jinze Dou, Adedayo Bello, Jari Koivisto, Kristoffer Meinander, Tiina Leiviskä, Tapani Vuorinen 2024

Microwave hydrolysis, as a sustainable approach in the processing of seaweed for protein and nanocellulose management

Anna Trubetskaya, Huy Quang Lê, Jenni Leppiniemi, Tetyana Koso, Teemu Välisalmi, Markus B. Linder, Italo Pisano, Jinze Dou, J. J. Leahy, Eero Kontturi 2024

Willow Bark-Derived Material with Antibacterial and Antibiofilm Properties for Potential Wound Dressing Applications

Jinze Dou, Polina Ilina, Cristina D. Cruz, Denise Nurmi, Paula Zegarra Vidarte, Marja Rissanen, Päivi Tammela, Tapani Vuorinen 2023

Willow bark proanthocyanidins with potential for water treatment: Chemical characterization and zinc/bisphenol A removal

Jinze Dou, Toni Varila, Juha-Pekka Salminen, Sari Tuomikoski, Sami Hietala, Maria Hemmi, Tao Hu, Ulla Lassi, Tapani Vuorinen 2023

In Situ Adsorption of Red Onion (Allium cepa) Natural Dye on Cellulose Model Films and Fabrics Exploiting Chitosan as a Natural Mordant

Rafael Grande, Riikka Räisänen, Jinze Dou, Satu Rajala, Kiia Malinen, Paula A. Nousiainen, Monika Österberg 2023

Effect of Hybrid Type and Harvesting Season on Phytochemistry and Antibacterial Activity of Extracted Metabolites from Salix Bark

Jinze Dou, Polina Ilina, Jarl Hemming, Kiia Malinen, Heidi Mäkkylä, Natália Oliveira De Farias, Päivi Tammela, Gisela De Aragão Umbuzeiro, Riikka Räisänen, Tapani Vuorinen 2022
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In September, 15 new Academy Researcher Fellows will start at Aalto

The Academy of Finland has granted Aalto University funding for 15 Academy Research Fellowships

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