Terhi Hakala - Academia.edu (original) (raw)

Papers by Terhi Hakala

Proceedings of 11th European Workshop on Lignocellulosics and Pulp. Hamburg, Germany, 16 - 19 Aug... more Proceedings of 11th European Workshop on Lignocellulosics and Pulp. Hamburg, Germany, 16 - 19 Aug. 2010, 153 - 157 Wood hemicellulose components, xylan and glucomannan, as well as lignin are interesting starting components for material applications, chemicals and liquid fuels. Thus, efficient and selective separation of these components from wood, pulp or process waters is of interest. With hydrolytic enzymes i.e. hemicellulases and cellulases the different carbohydrate components from lignocellulosic raw materials and pulps can be selectively decomposed. In this study enzymatic treatments were applied to enhance the lignin extraction from organosolv pulps. Organosolv pulps were obtained by cooking wood chips with the Lignofibre (LGF) process with acetic acid and phosphinic acid as catalyst. With the Lignofibre process it is possible to produce lignin rich, strong fibers with high yield. The enzymatic treatments were carried out before alkali extraction of the pulp to enhance the ex...

ABSTRACT : In this study we have collected information by interviewing all identified parties wit... more ABSTRACT : In this study we have collected information by interviewing all identified parties within the Finnish forest sector who might have a potential biotechnology connection : university research groups, research institutions, small and medium-sized biotechnology-companies and up to the largest forest companies. The ultimate goal was to assess how resources have been allocated and biotechnologies utilized within the value chain of the entire forest sector. This study aimed at providing answers to the following questions : • What are the current Finnish academic resources and projects related to forest industry biotechnology? • How much does the Finnish forest cluster invest in biotechnology R&D activity, and what are the key application areas in the value chain? • How well do the academic resources, company R&D investments and research needs converge to help secure the future competitiveness of the Finnish forest industries? In order to answer the questions above, the study app...

Applied Microbiology and Biotechnology

Manganese peroxidase (MnP) production in the white-rot basidiomycete Physisporinus rivulosus T241... more Manganese peroxidase (MnP) production in the white-rot basidiomycete Physisporinus rivulosus T241i was studied. Separate MnP isoforms were produced in carbon-limited liquid media supplemented with Mn(2+), veratryl alcohol, or sawdust. The isoforms had different pH ranges for the oxidation of Mn(2+) and 2,6-dimethoxyphenol. Although lignin degradation by white-rot fungi is often triggered by nitrogen depletion, MnPs of P. rivulosus were efficiently produced also in the presence of high-nutrient nitrogen, especially in cultures supplemented with veratryl alcohol. Two MnP encoding genes, mnpA and mnpB, were identified, and their corresponding cDNAs were characterized. Structurally, the genes showed marked dissimilarity, and the expression of the two genes implicated quantitative variation and differential regulation in response to manganese, veratryl alcohol, or sawdust. The variability in regulation and properties of the isoforms may widen the operating range for efficient lignin degr...

Journal of Agricultural and Food Chemistry, 2015

Pectinase treatment was used to facilitate protein recovery from defatted rapeseed (Brassica rapa... more Pectinase treatment was used to facilitate protein recovery from defatted rapeseed (Brassica rapa) cold-pressing residue in water-lean conditions and without pH adjustment. Effect of extraction pH on protein yield and physiochemical properties of the protein concentrates was assessed. Enzymatic hydrolysis of carbohydrates was feasible at high (40%) solid content and improved protein recovery at pH 6. Comparable protein yields (40-41% of total protein) from enzyme-aided water extraction (pH 6) and nonenzymatic alkaline extraction (pH10) at 10% solid content suggested that after enzymatic treatment, rapeseed protein could be extracted without exposure to alkali. However, water extraction required dilute conditions, whereas alkaline extraction was feasible also at 20% solid content. The water extracts possessed better protein solubility, higher ζ-potential, and smaller particle size than isoelectric precipitates from alkaline extraction, indicating higher dispersion stability. This is suggested to be mediated by electrostatic interactions between proteins and pectic carbohydrates in the water extracts.

Progress in Biotechnology, 2002

ABSTRACT Biopulping, i.e. treatment of wood chips by a suitable lignin-selective white-rot fungus... more ABSTRACT Biopulping, i.e. treatment of wood chips by a suitable lignin-selective white-rot fungus, has been successfully combined with mechanical pulping in the USA, and the process is now under commercalization. In contrast, biopulping combined with chemical pulping has been much less studied. The key factor for successful biopulping is to find a suitable fungus for the wood species of interest. More than 300 wood-rotting fungi, mostly newly isolated from old forests, were screened on plate tests, and the degradation of spruce wood blocks were tested by about 90 fungi. Suitable testing methods were developed and adopted to evaluate fungi that facilitate pulping. Most promising fungi were cultivated on spruce wood chips and the chips were then Kraft pulped. Some fungal treated samples were also mechanically pulped. Whiterot fungi usually produce organic acids such as oxalic acid during the degradation of lignin in wood. Therefore the compatibility of the fungal treatment with the present Kraft pulping practice is difficult to achieve, although the best fungi clearly degraded lignin and also improved alkali solubility of lignin.

Holzforschung, 2000

ABSTRACT Development of fiber strength properties and morphological changes on the surface of ble... more ABSTRACT Development of fiber strength properties and morphological changes on the surface of bleached hardwood kraft pulp after treatment with commercial cellobiohydrolase (CBH) was evaluated. Tensile and tear indices showed no significant effect of the treatment. The treatment resulted in reduction of wet zero-span strength, while the dry zero-span values increased. The decrease in wet zero-span values was most likely caused by preferential action of CBH on structurally irregular zones in the fiber wall coupled with greater sensitivity of wet zero-span testing towards the localized fiber defects. The fracture zone of the wet zero-span tested samples was imaged by scanning electron microscopy (SEM). Visual observation revealed differences in fiber fracture between treated and control samples. The straighter and cleaner fractures of the treated sample could be attributed to the localized hydrolytic action of CBH. Visual analysis of the treated fiber surface morphology by SEM showed an increase of more visible fiber wall dislocations, particularly on fibers of smaller diameter. The increased presence of the fiber dislocation correlates with the decrease in the wet zero-span values of treated samples.

Enzyme and Microbial Technology, 2004

Pre-treatment of wood chips with white-rot fungi (ie biopulping) has previously been shown to dec... more Pre-treatment of wood chips with white-rot fungi (ie biopulping) has previously been shown to decrease the energy consumption in mechanical pulping. In this study, promising novel fungal isolates were found for biopulping of Norway spruce (Picea abies). Three hundred ...

Enzyme and Microbial Technology, 2005

Carbohydrate Polymers, 2013

In this paper we describe the effect of enzyme treatments on the production of polymeric xylan, o... more In this paper we describe the effect of enzyme treatments on the production of polymeric xylan, oligosaccharides and hemicellulose lean pulp by alkaline extraction of bleached hardwood kraft pulp. Enzyme treatments were carried out before one or in between two subsequent alkaline extractions by purified Trichoderma reesei xylanase and endoglucanase II (Cel 5a) as well as by a commercial monocomponent endoglucanase (FibreCareR). Without enzyme pre-treatment 61% and 7% of the pulp xylan was extracted in high purity in the first and second alkaline stage, respectively. Higher molecular mass xylan was obtained in the second than in the first alkaline extraction. Xylanase treatment before alkaline extraction hydrolyzed up to 12% of xylan to xylooligosaccharides. According to our results, preparation of polymeric xylan, and/or oligosaccharides as well as hemicellulose lean pulp with cellulose content of 93-94%, is possible by enzyme-aided alkaline extraction process.

Biotechnology Letters, 2009

…, 2010

... Minna Blomstedt,a* Jaakko Asikainen,a Annina Lähdeniemi,b Timo Ylönen,b Jouni Paltakari,b and... more ... Minna Blomstedt,a* Jaakko Asikainen,a Annina Lähdeniemi,b Timo Ylönen,b Jouni Paltakari,b and Terhi K. Hakala a ... The heat-flux differential scanning calorimeter (Mettler 821e,Mettler-Toledo, Switzerland) was used for determining the amount of freezing and non-freezing ...

Applied Microbiology and Biotechnology, 2006

Applied Microbiology and Biotechnology, 2007