Browsing by Subject "WOOD"

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  • Randall, Ricardo S.; Miyashima, Shunsuke; Blomster, Tiina; Zhang, Jing; Elo, Annakaisa; Karlberg, Anna; Immanen, Juha; Nieminen, Kaisa; Lee, Ji-Young; Kakimoto, Tatsuo; Blajecka, Karolina; Melnyk, Charles W.; Alcasabas, Annette; Forzani, Celine; Matsumoto-Kitano, Miho; Mähönen, Ari Pekka; Bhalerao, Rishikesh; Dewitte, Walter; Helariutta, Yrjö; Murray, James A. H. (2015)
    Higher plant vasculature is characterized by two distinct developmental phases. Initially, a well-defined radial primary pattern is established. In eudicots, this is followed by secondary growth, which involves development of the cambium and is required for efficient water and nutrient transport and wood formation. Regulation of secondary growth involves several phytohormones, and cytokinins have been implicated as key players, particularly in the activation of cell proliferation, but the molecular mechanisms mediating this hormonal control remain unknown. Here we show that the genes encoding the transcription factor AINTEGUMENTA (ANT) and the D-type cyclin CYCD3;1 are expressed in the vascular cambium of Arabidopsis roots, respond to cytokinins and are both required for proper root secondary thickening. Cytokinin regulation of ANT and CYCD3 also occurs during secondary thickening of poplar stems, suggesting this represents a conserved regulatory mechanism.
  • Valoppi, Fabio; Lahtinen, Maarit; Bhattarai, Mamata; Kirjoranta, Satu; Juntti, Venla; Peltonen, Leena; Kilpeläinen, Petri O.; Mikkonen, Kirsi S. (2019)
    With the emerging bio-based technologies, the fractionation of complex biomass is essential to obtain value-added functional molecules for material, chemical, and energy production. The refining process of biomasses often requires the use of solvents and hazardous chemicals, whose removal after fractionation decreases the eco-compatibility of the process and increases the cost and time of the refinement. Softwood extracts obtained through the environmentally friendly pressurized hot water extraction are heterogeneous mixtures rich in hemicelluloses and lignin. Here we developed a simple, fast, organic solvent-free, and sustainable method to fractionate softwood extracts using centrifugal forces. The characteristics of each obtained fraction in terms of composition, macromolecular properties (particle size, molar mass, charge), interfacial activity, and stabilization capacity were highly dependent on the centrifugal force and time applied. The hemicellulose and lignin contents in the fractions were balanced by centrifugal forces to obtain functional emulsifiers that efficiently stabilized the oil/water interface. Through fractionation of softwood extracts, we also found that both the hemicelluloses and lignin particles are involved in emulsion interface formation and stabilization. Centrifugation is a scalable concept that can be feasibly and easily introduced into the biorefinery system and used to optimize the composition of biomass fractions for targeted purposes.
  • Aaen, Ragnhild; Lehtonen, Mari; Mikkonen, Kirsi S.; Syverud, Kristin (2021)
    The use of wood-derived cellulose nanofibrils (CNFs) or galactoglucomannans (GGM) for emulsion stabilization may be a way to obtain new environmentally friendly emulsifiers. Both have previously been shown to act as emulsifiers, offering physical, and in the case of GGM, oxidative stability to the emulsions. Oil-in-water emulsions were prepared using highly charged (1352 ± 5 µmol/g) CNFs prepared by TEMPO-mediated oxidation, or a coarser commercial CNF, less charged (≈ 70 µmol/g) quality (Exilva forte), and the physical emulsion stability was evaluated by use of droplet size distributions, micrographs and visual appearance. The highly charged, finely fibrillated CNFs stabilized the emulsions more effectively than the coarser, lower charged CNFs, probably due to higher electrostatic repulsions between the fibrils, and a higher surface coverage of the oil droplets due to thinner fibrils. At a constant CNF/oil ratio, the lowest CNF and oil concentration of 0.01 wt % CNFs and 5 wt % oil gave the most stable emulsion, with good stability toward coalescence, but not towards creaming. GGM (0.5 or 1.0 wt %) stabilized emulsions (5 wt % oil) showed no creaming behavior, but a clear bimodal distribution with some destabilization over the storage time of 1 month. Combinations of CNFs and GGM for stabilization of emulsions with 5 wt % oil, provided good stability towards creaming and a slower emulsion destabilization than for GGM alone. GGM could also improve the stability towards oxidation by delaying the initiation of lipid oxidation. Use of CNFs and combinations of GGM and CNFs can thus be away to obtain stable emulsions, such as mayonnaise and beverage emulsions.
  • Ahvenainen, Patrik; Kontro, Inkeri; Svedström, Kirsi (2016)
    Cellulose crystallinity assessment is important for optimizing the yield of cellulose products, such as bioethanol. X-ray diffraction is often used for this purpose for its perceived robustness and availability. In this work, the five most common analysis methods (the Segal peak height method and those based on peak fitting and/or amorphous standards) are critically reviewed and compared to two-dimensional Rietveld refinement. A larger () and more varied collection of samples than previous studies have presented is used. In particular, samples () with low crystallinity and small crystallite sizes are included. A good linear correlation () between the five most common methods suggests that they agree on large-scale crystallinity differences between samples. For small crystallinity differences, however, correlation was not seen for samples that were from distinct sample sets. The least-squares fitting using an amorphous standard shows the smallest crystallite size dependence and this method combined with perpendicular transmission geometry also yielded values closest to independently obtained cellulose crystallinity values. On the other hand, these values are too low according to the Rietveld refinement. All analysis methods have weaknesses that should be considered when assessing differences in sample crystallinity.
  • Tanaka, Atsushi; Khakalo, Alexey; Hauru, Lauri; Korpela, Antti; Orelma, Hannes (2018)
    In this study, we investigate the “chemical welding” of paper with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) using a two-step process. First, the IL is transported into the structure of the paper as a water solution. Then, partial dissolution is achieved by activation with heat (80–95 °C), where the water evaporates and the surfaces of the fibres partially dissolve. The activated paper is washed with water to remove IL, and dried to fuse fibre surfaces into each other. The “chemically welded” paper structure has both elevated dry and wet strength. The treatment conditions can be adjusted to produce both paper-like materials and films. The most severe treatment conditions produce films that are fully transparent and their oxygen and grease barrier properties are excellent. As an all-cellulose material, the “chemically welded” paper is fully biodegradable and is a potential alternative to fossil fuel-based plastics.
  • Korhonen, Jaana; Miettinen, Jenni; Kylkilahti, Eliisa; Tuppura, Anni; Autio, Minna; Lähtinen, Katja; Pätäri, Satu; Pekkanen, Tiia-Lotta; Luhas, Jukka; Mikkilä, Mirja; Linnanen, Lassi; Ollikainen, Markku; Toppinen, Anne (2021)
    It is uncertain how the traditional forest sector can respond to the changing political environment, evolving markets, and global environmental problems. This study focuses on the development of forest-based bioeconomy (BE) in Finland from the perspective of three forest-based value networks (wooden multistory construction, fiber-based packaging, and biorefining) and thus breaks the tendency of siloed discussions. The study of expert opinions applies a collaborative interdisciplinary research method that combines group discussions and follow-up survey data. The results indicate that transformational regulation, proper incentives, and ways of increasing interaction at the business-consumer interface are required to support the creation of new practices and the destruction of old practices in the industry renewal. (C) 2021 The Authors. Published by Elsevier Ltd.
  • Chen, Jia-Jia; Wang, Ling-Yan; Immanen, Juha; Nieminen, Kaisa; Spicer, Rachel; Helariutta, Ykä; Zhang, Jing; He, Xin-Qiang (2019)
    Tissue regeneration upon wounding in plants highlights the developmental plasticity of plants. Previous studies have described the morphological and molecular changes of secondary vascular tissue (SVT) regeneration after large-scale bark girdling in trees. However, how phytohormones regulate SVT regeneration is still unknown. Here, we established a novel in vitro SVT regeneration system in the hybrid aspen (Populus tremula x Populus tremuloides) clone T89 to bypass the limitation of using field-grown trees. The effects of phytohormones on SVT regeneration were investigated by applying exogenous hormones and utilizing various transgenic trees. Vascular tissue-specific markers and hormonal response factors were also examined during SVT regeneration. Using this in vitro regeneration system, we demonstrated that auxin and cytokinin differentially regulate phloem and cambium regeneration. Whereas auxin is sufficient to induce regeneration of phloem prior to continuous cambium restoration, cytokinin only promotes the formation of new phloem, not cambium. The positive role of cytokinin on phloem regeneration was further confirmed in cytokinin overexpression trees. Analysis of a DR5 reporter transgenic line further suggested that cytokinin blocks the re-establishment of auxin gradients, which is required for the cambium formation. Investigation on the auxin and cytokinin signalling genes indicated these two hormones interact to regulate SVT regeneration. Taken together, the in vitro SVT regeneration system allows us to make use of various molecular and genetic tools to investigate SVT regeneration. Our results confirmed that complementary auxin and cytokinin domains are required for phloem and cambium reconstruction.
  • Heiskanen, Aleksi; Hurmekoski, Elias; Toppinen, Anne; Näyhä, Annukka (2022)
    The forest-based sector is facing one the greatest transitions in its history in the face of global megatrends. Globalization, sustainability challenges and the ICT sector have put the world in a new light. Whereas some of the recent developments have resulted in challenges for the traditional forest industry, many positive expectations and opportunities are also seen to arise in the form of the transition to a sustainable bio-economy. However, to be able to fully seize the opportunity, the industry has to navigate through contingency where preparedness can have a major impact. Foresight as a strategic approach can help to prepare and sensitize decision-makers to be prepared for the future. Foresight is a process aimed at understanding the various and alternative developments of the future better. In this review, we aim to find out what the state-of-the-art of qualitative foresight in the context of forest-based sector is. Forest sector foresight remains a nascent stream in peer-reviewed literature despite the small increase in articles since 2010. Foresight has been applied relatively evenly across the sub-sectors, attention having been predominantly on adaptive approaches. Foresight studies could be classified based on their objectives and types of output into three main categories: Identifying Drivers and Trends, Management of Change and Visioning. Notably, almost all the scientific foresight literature deals with sectoral level, and lacks organisational points of view. Foresight could also provide an opportunity to include stakeholder engagement beyond business-as-usual, which seems to remain currently relatively marginal. The findings suggests that foresight in the forest sector is not entirely novel, but still developing. Many opportunities to fully capture the potential lie ahead and micro level perspectives could be enhanced in the literature.
  • Hyväkkö, Uula; King, Alistair W. T.; Kilpeläinen, Ilkka (2014)
  • Jyske, Tuula; Brännström, Hanna; Sarjala, Tytti; Hellström, Jarkko; Halmemies, Eelis; Raitanen, Jan-Erik; Kaseva, Janne; Lagerquist, Lucas; Eklund, Patrik; Nurmi, Juha (2020)
    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 H(2)O(2)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.
  • Mukrimin, Mukrimin; Conrad, Anna O.; Kovalchuk, Andriy; Julkunen-Tiitto, Riitta; Bonello, Pierluigi; Asiegbu, Fred O. (2019)
    Conifer trees, including Norway spruce, are threatened by fungi of the Heterobasidion annosum species complex, which severely affect timber quality and cause economic losses to forest owners. The timely detection of infected trees is complicated, as the pathogen resides within the heartwood and sapwood of infected trees. The presence of the disease and the extent of the wood decay often becomes evident only after tree felling. Fourier-transform infrared (FT-IR) spectroscopy is a potential method for non-destructive sample analysis that may be useful for identifying infected trees in this pathosystem. We performed FT-IR analysis of 18 phloem, 18 xylem, and 18 needle samples from asymptomatic and symptomatic Norway spruce trees. FT-IR spectra from 1066 – 912 cm−1 could be used to distinguish phloem, xylem, and needle tissue extracts. FT-IR spectra collected from xylem and needle extracts could also be used to discriminate between asymptomatic and symptomatic trees using spectral bands from 1657 – 994 cm−1 and 1104 – 994 cm−1, respectively. A partial least squares regression model predicted the concentration of condensed tannins, a defense-related compound, in phloem of asymptomatic and symptomatic trees. This work is the first to show that FT-IR spectroscopy can be used for the identification of Norway spruce trees naturally infected with Heterobasidion spp.
  • Daly, Paul; Peng, Mao; Di Falco, Marcos; Lipzen, Anna; Wang, Mei; Ng, Vivian; Grigoriev, Igor; Tsang, Adrian; Makela, Miia R.; de Vries, Ronald P. (2019)
    The extent of carbon catabolite repression (CCR) at a global level is unknown in wood-rotting fungi, which are critical to the carbon cycle and are a source of biotechnological enzymes. CCR occurs in the presence of sufficient concentrations of easily metabolizable carbon sources (e.g., glucose) and involves downregulation of the expression of genes encoding enzymes involved in the breakdown of complex carbon sources. We investigated this phenomenon in the white-rot fungus Dichomitus squalens using transcriptomics and exoproteomics. In D. squalens cultures, approximately 7% of genes were repressed in the presence of glucose compared to Avicel or xylan alone. The glucose-repressed genes included the essential components for utilization of plant biomass-carbohydrate-active enzyme (CAZyme) and carbon catabolic genes. The majority of polysaccharide-degrading CAZyme genes were repressed and included activities toward all major carbohydrate polymers present in plant cell walls, while repression of ligninolytic genes also occurred. The transcriptome-level repression of the CAZyme genes observed on the Avicel cultures was strongly supported by exoproteomics. Protease-encoding genes were generally not glucose repressed, indicating their likely dominant role in scavenging for nitrogen rather than carbon. The extent of CCR is surprising, given that D. squalens rarely experiences high free sugar concentrations in its woody environment, and it indicates that biotechnological use of D. squalens for modification of plant biomass would benefit from derepressed or constitutively CAZyme-expressing strains. IMPORTANCE White-rot fungi are critical to the carbon cycle because they can mineralize all wood components using enzymes that also have biotechnological potential. The occurrence of carbon catabolite repression (CCR) in white-rot fungi is poorly understood. Previously, CCR in wood-rotting fungi has only been demonstrated for a small number of genes. We demonstrated widespread glucose-mediated CCR of plant biomass utilization in the white-rot fungus Dichomitus squalens. This indicates that the CCR mechanism has been largely retained even though wood-rotting fungi rarely experience commonly considered CCR conditions in their woody environment. The general lack of repression of genes encoding proteases along with the reduction in secreted CAZymes during CCR suggested that the retention of CCR may be connected with the need to conserve nitrogen use during growth on nitrogen-scarce wood. The widespread repression indicates that derepressed strains could be beneficial for enzyme production.
  • Carvalho, Danila M.d.; Berglund, Jennie; Marchand, Célia; Lindström, Mikael E.; Vilaplana, Francisco; Sevastyanova, Olena (2019)
    The impact of various degrees of acetylation on improving the thermal stability of xylan isolated from different botanical source has been studied; methylglucuronoxylan from birch and eucalyptus, arabinoglucuronoxylan from spruce and glucuronoarabinoxylan from sugarcane bagasse and straw. The lower molecular weight of nonacetylated methylglucuronoxylan (17.7-23.7 kDa) and arabinoglucuronoxylan (16.8 kDa) meant that they were more soluble in water than glucuronoarabinoxylan (43.0-47.0 kDa). The temperature at the onset of degradation increased by 17-61 degrees C and by 75-145 degrees C for low and high acetylated xylans respectively, as a result of acetylation. A glass transition temperature in the range of 121-132 degrees C was observed for the samples non-acetylated and acetylated at low degree of acetylation (0.0-0.6). The acetylation to higher degrees (1.4-1.8) increased the glass transition temperature of the samples to 189-206 degrees C. Acetylation proved to be an efficient method for functionalization of the xylan to increase the thermal stability.
  • Lopez, Sara Casado; Peng, Mao; Issak, Tedros Yonatan; Daly, Paul; de Vries, Ronald P.; Mäkelä, Miia R. (2018)
    Fungi can decompose plant biomass into small oligo-and monosaccharides to be used as carbon sources. Some of these small molecules may induce metabolic pathways and the production of extracellular enzymes targeted for degradation of plant cell wall polymers. Despite extensive studies in ascomycete fungi, little is known about the nature of inducers for the lignocellulolytic systems of basidiomycetes. In this study, we analyzed six sugars known to induce the expression of lignocellulolytic genes in ascomycetes for their role as inducers in the basidiomycete white-rot fungus Dichomitus squalens using a transcriptomic approach. This identified cellobiose and L-rhamnose as the main inducers of cellulolytic and pectinolytic genes, respectively, of D. squalens. Our results also identified differences in gene expression patterns between dikaryotic and monokaryotic strains of D. squalens cultivated on plant biomass-derived monosaccharides and the disaccharide cellobiose. This suggests that despite conservation of the induction between these two genetic forms of D. squalens, the fine-tuning in the gene regulation of lignocellulose conversion is differently organized in these strains. IMPORTANCE Wood-decomposing basidiomycete fungi have a major role in the global carbon cycle and are promising candidates for lignocellulosic biorefinery applications. However, information on which components trigger enzyme production is currently lacking, which is crucial for the efficient use of these fungi in biotechnology. In this study, transcriptomes of the white-rot fungus Dichomitus squalens from plant biomass-derived monosaccharide and cellobiose cultures were studied to identify compounds that induce the expression of genes involved in plant biomass degradation.
  • Bock, Peter; Nousiainen, Paula; Elder, Thomas; Blaukopf, Markus; Amer, Hassan; Zirbs, Ronald; Potthast, Antje; Gierlinger, Notburga (2020)
    Vibrational spectroscopy is a very suitable tool for investigating the plant cell wall in situ with almost no sample preparation. The structural information of all different constituents is contained in a single spectrum. Interpretation therefore heavily relies on reference spectra and understanding of the vibrational behavior of the components under study. For the first time, we show infrared (IR) and Raman spectra of dibenzodioxocin (DBDO), an important lignin substructure. A detailed vibrational assignment of the molecule, based on quantum chemical computations, is given in the Supporting Information; the main results are found in the paper. Furthermore, we show IR and Raman spectra of synthetic guaiacyl lignin (dehydrogenation polymer-G-DHP). Raman spectra of DBDO and G-DHP both differ with respect to the excitation wavelength and therefore reveal different features of the substructure/polymer. This study confirms the idea previously put forward that Raman at 532 nm selectively probes end groups of lignin, whereas Raman at 785 nm and IR seem to represent the majority of lignin substructures.
  • Mansikkala, Tuomas; Patanen, Minna; Karkonen, Anna; Korpinen, Risto; Pranovich, Andrey; Ohigashi, Takuji; Swaraj, Sufal; Seitsonen, Jani; Ruokolainen, Janne; Huttula, Marko; Saranpaa, Pekka; Piispanen, Riikka (2020)
    Lignans are bioactive compounds that are especially abundant in the Norway spruce (Picea abiesL. Karst.) knotwood. By combining a variety of chromatographic, spectroscopic and imaging techniques, we were able to quantify, qualify and localise the easily extractable lignans in the xylem tissue. The knotwood samples contained 15 different lignans according to the gas chromatography-mass spectrometry analysis. They comprised 16% of the knotwood dry weight and 82% of the acetone extract. The main lignans were found to be hydroxymatairesinols HMR1 and HMR2. Cryosectioned and resin-embedded ultrathin sections of the knotwood were analysed with scanning transmission X-ray microscopy (STXM). Cryosectioning was found to retain only lignan residues inside the cell lumina. In the resin-embedded samples, lignan was interpreted to be unevenly distributed inside the cell lumina, and partially confined in deposits which were either readily present in the lumina or formed when OsO(4)used in staining reacted with the lignans. Furthermore, the multi-technique characterisation enabled us to obtain information on the chemical composition of the structural components of knotwood. A simple spectral analysis of the STXM data gave consistent results with the gas chromatographic methods about the relative amounts of cell wall components (lignin and polysaccharides). The STXM analysis also indicated that a torus of a bordered pit contained aromatic compounds, possibly lignin.
  • Dou, Jinze; Karakoc, Alp; Johansson, Leena-Sisko; Hietala, Sami; Evtyugin, Dmitr; Vuorinen, Tapani (2021)
    High surface lignin content (i.e. 34.6 %) sclerenchyma fiber bundles were successfully isolated with a yield of 71 % by a mild alkali (NaOH dosage of 5 wt%) extraction of eucalyptus (Eucalyptus globulus) bark under 100 degrees C for 60 min.. The mechanical properties of the composites prepared by hot pressing of cellulose acetate butyrate (CAB) sheets with the fiber bundles were evaluated. The fiber bundles exhibited good compatibility with CAB due to their hydrophobic fiber surfaces. The mechanical properties of the fiber bundle/ cellulose acetate butyrate composites revealed the maximum at a weight ratio of 25:75, which demonstrates the promise of utilizing these isotropic aligned fiber bundles as the reinforcement to the cellulose acetate butyrate without the addition of plasticizers for composite uses.
  • Giummarella, Nicola; Balakshin, Mikhail; Koutaniemi, Sanna; Karkonen, Anna; Lawoko, Martin (2019)
    The question of whether lignin is covalently linked to carbohydrates in native wood, forming what is referred to as lignin-carbohydrate complexes (LCCs), still lacks unequivocal proof. This is mainly due to the need to isolate lignin from woody materials prior to analysis, under conditions leading to partial chemical modification of the native wood polymers. Thus, the correlation between the structure of the isolated LCCs and LCCs in situ remains open. As a way to circumvent the problematic isolation, biomimicking lignin polymerization in vivo and in vitro is an interesting option. Herein, we report the detection of lignin-carbohydrate bonds in the extracellular lignin formed by tissue-cultured Norway spruce cells, and in modified biomimetic lignin synthesis (dehydrogenation polymers). Semi-quantitative 2D heteronuclear singular quantum coherence (HSQC)-, P-31 -, and C-13-NMR spectroscopy were applied as analytical tools. Combining results from these systems, four types of lignin-carbohydrate bonds were detected; benzyl ether, benzyl ester, gamma-ester, and phenyl glycoside linkages, providing direct evidence of lignin-carbohydrate bond formation in biomimicked lignin polymerization. Based on our findings, we propose a sequence for lignin-carbohydrate bond formation in plant cell walls.
  • Lehtonen, Mari; Merinen, Maria; Kilpeläinen, Petri O.; Xu, Chunlin; Willför, Stefan M.; Mikkonen, Kirsi S. (2018)
    Hypothesis: Amphiphilic character of surfactants drives them at the interface of dispersed systems, such as emulsions. Hemicellulose-rich wood extracts contain assemblies (lignin-carbohydrate complexes, LCC) with natural amphiphilicity, which is expected to depend on their chemical composition resulting from the isolation method. Lignin-derived phenolic residues associated with hemicelluloses are hypothesized to contribute to emulsions' interfacial properties and stability. Experiments: We investigated the role of phenolic residues in spruce hemicellulose extracts in the stabilization of oil-in-water emulsions by physical and chemical approach. Distribution and changes occurring in the phenolic residues at the droplet interface and in the continuous phase were studied during an accelerated storage test. Meanwhile, the physical stability and lipid oxidation in emulsions were monitored. Findings: Naturally associated lignin residues in GGM act as vehicles for anchoring these hemicelluloses into the oil droplet interface and further enable superior stabilization of emulsions. By adjusting the isolation method of GGM regarding their phenolic profile, their functionalities, especially interfacial behavior, can be altered. Retaining the native interactions of GGM and phenolic residues is suggested for efficient physical stabilization and extended protection against lipid oxidation. The results can be widely applied as guidelines in tailoring natural or synthetic amphiphilic compounds for interfacial stabilization. (C) 2017 Elsevier Inc. All rights reserved.
  • Taboada-Puig, Roberto; Lu-Chau, Thelmo A.; Moreira, Maria T.; Feijoo, Gumersindo; Lema, Juan M.; Fagerstedt, Kurt; Ohra-Aho, Taina; Liitia, Tiina; Heikkinen, Harri; Ropponen, Jarmo; Tamminen, Tarja (2018)
    The objective of this study was to evaluate the ability of one versatile peroxidase and the biocatalytically generated complex Mn(III)-malonate to polymerize coniferyl alcohol (CA) to obtain dehydrogenation polymers (DHPs) and to characterize how closely the structures of the formed DHPs resemble native lignin. Hydrogen peroxide was used as oxidant and Mn2+ as mediator. Based on the yields of the polymerized product, it was concluded that the enzymatic reaction should be performed in aqueous solution without organic solvents at 4.5pH6.0 and with 0.75H(2)O(2):CA ratio1. The results obtained from the Mn3+-malonate-mediated polymerization showed that the yield was almost 100%. Reaction conditions had, however, effect on the structures of the formed DHPs, as detected by size exclusion chromatography and pyrolysis-GC/MS. It can be concluded that from the structural point of view, the optimal pH for DHP formation using the presently studied system was 3 or 4.5. Low H2O2/CA ratio was beneficial to avoid oxidative side reactions. However, the high frequency of - linkages in all cases points to dimer formation between monomeric CA rather than endwise polymerization. (c) 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:81-90, 2018