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Constituents of bark
... Many bark extractives show bioactivity such as antifungal, anti-tumor, anti-carcinogenic, anti-diabetic and anti-inflammatory activity and hence, are gaining attention from researchers as therapeutic agents. [4] The structural biopolymers of bark are of emerging interest for the production of bio-based chemicals and materials. [5][6][7] Pinus radiata bark represents a significant and growing waste product within New Zealand and, other than boiler fuel, has limited high value applications at present. ...
... Bark extraction processes have traditionally utilized organic solvents and water to separate the extractives from the structural biopolymers of bark. [4,8] For example, an extractive content of loblolly pine (Pinus taeda) bark of up to 27.5% was observed by performing sequential and exhaustive extractions using hexane, benzene, ethyl ether, ethanol, water and 1% NaOH. [4] The issue of exhaustive extractions following this approach is the need for volatile and often flammable solvents and energy intensive distillation processes for the subsequent isolation of the extracts. ...
... [4,8] For example, an extractive content of loblolly pine (Pinus taeda) bark of up to 27.5% was observed by performing sequential and exhaustive extractions using hexane, benzene, ethyl ether, ethanol, water and 1% NaOH. [4] The issue of exhaustive extractions following this approach is the need for volatile and often flammable solvents and energy intensive distillation processes for the subsequent isolation of the extracts. ...
Ionic liquids (ILs) are being increasingly explored as extraction solvents due to their tunable properties, which can control their ability to dissolve an array of solutes. IL selection requires an in-depth understanding of the consequences of IL structure on extraction outcomes for different substrates. Here, 14 ILs containing cations and anions that have been systematically modified to examine key structural effects have been explored for the extraction of chemical components from Pinus radiata bark. The extraction efficiency relative to the mass of bark ranged from 4 to 70%, and the isolation of bark components was evaluated using antisolvent addition. Extraction outcomes highlighted the importance of the IL anion in affecting extraction efficiency and selectivity, with a secondary role from the IL cation, and point toward a simple route for improving the overall selectivity of biomass extractions through control of the antisolvent addition process.
... In general, bark differs from wood by a lower percentage of sugars, of which glucose is the most abundant, followed by mannose and xylose. Compared to other softwoods, bark of Scots pine contains more lignin and the main hemicellulose is galactoglucomannan (Fengel and Wegener, 1989 ). Bark has also higher percentage of extractives than stemwood (Fengel and Wegener, 1989). ...
... In general, bark differs from wood by a lower percentage of sugars, of which glucose is the most abundant, followed by mannose and xylose. Compared to other softwoods, bark of Scots pine contains more lignin and the main hemicellulose is galactoglucomannan (Fengel and Wegener, 1989 ). Bark has also higher percentage of extractives than stemwood (Fengel and Wegener, 1989). Previous studies have reported the composition (Matthews et al., 1997; Pan and Lundgren, 1996 ), distribution and structural characteristics , as well as functional properties of procyanidins, phenolic extractives with antioxidant capacity, isolated from Scots pine bark (Karonen et al., 2004). ...
... The three main unsaturated fatty acids (oleic, linoleic and linolenic acids) were the same as in wood, although in lower concentrations (Table 2) (Dorado et al., 2000). As in other bark types (Fengel and Wegener, 1989; Fradinho et al., 2002), pine bark contained more lignin than cellulose and hemicellulose, of which the content of cellulose was predominant (Table 1 ). The carbohydrate analyses using acid methanolysis revealed that pine bark contained mainly arabinose and mannose (Table 1). ...
The composition of Scots pine bark, its degradation, and the production of hydrolytic and ligninolytic enzymes were evaluated during 90 days of incubation with Phanerochaete velutina and Stropharia rugosoannulata. The aim was to evaluate if pine bark can be a suitable fungal substrate for bioremediation applications. The original pine bark contained 45% lignin, 25% cellulose, and 15% hemicellulose. Resin acids were the most predominant lipophilic extractives, followed by sitosterol and unsaturated fatty acids, such as linoleic and oleic acids. Both fungi degraded all main components of bark, specially cellulose (79% loss by P. velutina). During cultivation on pine bark, fungi also degraded sitosterol, produced malic acid, and oxidated unsaturated fatty acids. The most predominant enzymes produced by both fungi were cellulase and manganese peroxidase. The results indicate that Scots pine bark supports enzyme production and provides nutrients to fungi, thus pine bark may be suitable fungal substrate for bioremediation.
... These bonds confer significant resistance against degradation (Carlile et al., 2015). On the other hand, the biological degradation susceptibility of conifer wood fiber can be especially attributed to the high decomposing vulnerability of cellulose and hemicellulose (Fengel and Wegener, 1989). In the present study, the observed change in hemicellulose (and to lesser extent lignin) percentage in wood fiber (Figure 1) is likely related to the proportional decrease in percentage of cellulose which led to an overall increase of percentage share of other constituents. ...
Introduction
Production of strawberries in greenhouses and polytunnels is gaining popularity worldwide. This study investigated the effect of reuse of coir and peat, two substrates commonly adapted to soilless strawberry production, as well as stand-alone wood fiber from Norway spruce, a promising substrate candidate.
Methods
The experiment was performed in a polytunnel at NIBIO Apelsvoll, Norway, and evaluated both virgin substrates, as well as spent materials that were used in one or two years. Yield, berry quality and plant architecture of the strawberry cultivar ‘Malling Centenary’ were registered. In addition, chemical and physical properties of virgin and reused substrates were investigated.
Results
While plants grown in peat and wood fiber had highest yield in the first year of production, the berry yield was slightly reduced when these substrates were utilized for the second and third time. However, yield was comparable to the yield level attained in new and reused coir. Interestingly, berries grown in wood fiber had a tendency to a higher sugar accumulation. This substrate also produced the highest plants. Stand-alone wood fiber was the substrate with the highest accumulation of nitrogen during the three consecutive production cycles. All three investigated materials revealed a trend for decreased potassium accumulation. Wood fiber is characterized by the highest percentage of cellulose, however after three years of production the cellulose content was reducedto the same levels as for coir and peat.
Discussion
Implementation of wood fiber as a growing medium, as well as general practice of substrate reuse can be therefore an achievable strategy for more sustainable berry production.
... The extractive content in woody biomass varies between 2-15% while the content in bark is about 20-40% [60,74]. Extractives comprise a large number of substances in biomass such as volatile matters like terpenes, resins, fats, waxes, tannins, lignan and carbohydrates [75]. ...
... Beside lignin further types of polyphenols like flavanols, tannins, polyphenolic acids, catechins and lignans are found in bark (Fengel and Wegener, 2003;Valentin et al., 2010). However, these substances are not distinguished by the applied analytical methods. ...
The implementation of a lignocellulose-based biorefinery requires an efficient fractionation of its raw material. For this purpose a comprehensive biorefinery concept has been developed based on alkaline polyol pulping (AlkaPolP). It exhibits a high degree of flexibility with respect to the extent of fractionation by adjusting easily controllable process parameters. As shown in this contribution, the AlkaPolP process can be successfully applied for a wide range of lignocellulosic biomass including hardwood, softwood, bark and grasses, all of which yielding high quality product fractions.
... Other materials such as bark contain phenolic substances and levels of lignin (20-30%) comparable to those in peat and coir but are less stable (Maher et al., 2008). Degradation of bark and wood fiber may be linked to the ready decomposition of cellulose and easily hydrolyzable substances such as arabinoglucuronoxylans, present as the principal hemicellulose in coniferous wood and bark (Fengel and Wegener, 1989). Media prepared from less stable components may decompose in storage and use (Carlile, 2004;Prasad and Maher, 2004), resulting in shrinkage of media in pots and, in some cases, N immobilization (Dickinson and Carlile, 1995). ...
Organic growing media are essentially bulk products. Availability in large quantity allied to its excellent air and water retention, low pH and salinity, and freedom from pests and diseases has led to peat being the dominant organic constituent of growing media in many parts of the world for the last 50 yr. The unique microporous properties of Sphagnum peat and its resistance to degradation are matched by few other growing media constituents. Nevertheless, local scarcity of Sphagnum peat and the expense of transport has led to the use of other materials in growing media. Notable among these is coir, which unlike peat, a CO2 sink, is widely regarded as a rapidly renewable resource. Indeed, advances in processing and quality control in situ have led to a huge upsurge in the export and use of coir in growing media, particularly in Europe but also in the western United States. Locally available organic materials such as bark, composted materials including green (yard) wastes, municipal solid wastes, and even sewage sludge are also used in growing media. While possessing advantages such as the high air content of bark and nutrient supply of many composted materials, these media components may have disadvantages, from limited supplies due to bioenergy pulls and N lock-up in bark, to physical, chemical, and microbial contaminants in composts. Current innovative approaches involve increasing use of wood fiber in Europe, whole pine-tree thinnings in the United States, and realizing the use and transformation of composted wastes as next-generation constituents of growing media.
... In a recent work, Pujol et al. (2013) reported a polysaccharides content of 14 % for GS. Compared to other lignocellulosic materials extractives solubilised from GS by the alkaline solution are higher than those reported for the maritime pine bark from Portugal (11 %) (Frandinho et al. 2002) and within the range of various pine barks (17.2-39.1 %) (Fengel and Wegener 1984). Elemental composition and elemental ratios of raw GS and treated biomasses are given in Table 2. ...
In this work, metal sorption onto grape stalks waste structural compounds and extractives has been studied for determining their role in Cr(VI), Cu(II) and Ni(II) metal sorption. For this purpose, a sequential extraction of extractives and other compounds from the lignocellulosic material has been carried out. The resulting solid samples obtained in the different extraction processes were used as sorbents of Cr(VI), Cu(II) and Ni(II). Sorption results were discussed taking into account the elemental composition and polarity of the solid extracts. Results indicated that tannins and poly-phenols are involved in chromium reduction and sorp-tion. Lignin and celluloses are involved in chromium, Cu(II) and Ni(II) sorption. FTIR analysis confirmed the involvement of lignin moieties in the studied metal ions sorption by grape stalks waste. This study presents a new approach on metal sorption field as the knowledge of the role of the sorbent chemical compounds is essential to determine the key sorbent compounds in the sorption process.
... Norway spruce (Picea abies) is the most abundant coniferous tree growing in Northern Europe and it is extensively used in the Scandinavian pulp and paper industry. The bark of Norway spruce represents about 10% of the weight of the tree trunk (Fengel & Wegener, 1983). Due to its resistance to pulping and its high content of extractives, bark is considered to be an undesirable material in the pulp and paper production. ...
Maritime pine, scientifically known as Pinus pinaster, holds a vital role in Iberian Peninsula forests, primarily as a source of wood for panels, paper, and cellulose production. Recently, there has been a growing interest in utilising agroforestry by-products to yield valuable chemicals for applications in various sectors, including the food, pharmaceutical, and bioenergy industries. This study aimed to assess the value of the primary by-product of Pinus pinaster from the Minho region of northwestern Portugal, i.e., the bark. The research extensively examined the bark’s chemical and thermal characteristics, including ash content, extractives, lignin, cellulose, hemicellulose, fatty acids, and mineral composition. Additionally, various analytical techniques like FTIR, SEM, DSC, DTG, and XRD were used to observe chemical structure differences. The results reveal that the Pinus pinaster bark primarily consists of lignin (51.15%) and holocellulose (46.09%), with extractives mainly soluble in toluene–ethanol, followed by water, and a small amount of them are soluble in ethanol. The bark contained around 0.44% ash, and heavy metals such as Cd and Pb were not found. During degradation, Pinus pinaster experienced a 10% mass loss at 140 °C. In terms of crystallinity, holocellulose and cellulose showed similar percentages at approximately 25.5%, while α-cellulose displayed the highest crystallinity index at 41%.
Tree bark is a by-product of the wood industry and has currently only little use as raw material. In this study, spruce bark disintegrated into three different types of particles was used to obtain porous structures with a wide range of properties. The manufacturing process includes a simple mechanical foaming method, using bark particles, a common wood adhesive, a surfactant and water. Physical and mechanical characterization of the materials was carried out in terms of density, thermal conductivity, water uptake, compression resistance and microscopy observation. All materials produced presented a heterogeneous open porous structure. Thermal conductivity values range between 0.075 and 0.125 W m ⁻¹ K ⁻¹ , while the density values range between 100 and 650 kg/m ³ . Water uptake percentage varies between groups but is stabilized after 24 h of immersion, and in some cases, the water uptake reaches up to 450%. Regarding the mechanical properties, they vary greatly showing a tendency of decreasing when adding higher amounts of surfactant.
The food market is demanding natural antioxidants either to be applied to food or cosmetic and nutraceutical purposes. Plants are very rich in polyphenols that have diverse biological functions, such as defending plants against microbiological attacks, becoming essential to plant life. The bark of Pinus pinaster Aiton subsp. atlantica is known to have a great amount of polyphenols with antioxidant and antimicrobial properties. P. pinaster has a large area of distribution in the northwest of Portugal, making this source a biomass feedstock of great interest for the food industry in Portugal. Therefore, embarking on the trend of circular economy, polyphenols are being extracted aiming for the exploitation of their antioxidant and antimicrobial properties as a food additive in a variety of food matrices. This chapter aims to provide a more insightful view of the chemical composition, extraction methods, and food applications of pine bark of Pinus pinaster Aiton subsp. atlantica polyphenols.
Ausgehend von der bestehenden Idee eines Lignocelluloseaufschlusses in einem alkalischen Polyol (Alkaline Polyol Pulping = AlkaPolP) wurden im Rahmen dieser Arbeit ein Aufschlussprozess für Lignocellulosen in alkalischem Glycerin sowie die nachgeschaltete Aufbereitung der Produktströme entwickelt und gezeigt, dass diese den Ausgangspunkt eines vielversprechenden Bioraffineriekonzeptes bilden können. Es wurde nachgewiesen, dass der AlkaPolP-Prozess für alle Arten von Lignocellulose geeignet ist und diese innerhalb weniger Minuten nahezu vollständig delignifiziert.
Im Rahmen des Downstream Processings der Aufschlussprodukte wurden die enzymatische Hydrolyse des Zellstoffes, die Ligninfällung sowie die Aufreinigung des Ligninfiltrates genauer untersucht.
Ein Vergleich mit Literaturdaten anderer Verfahren zur Lignocellulosefraktionierung zeigte, dass mit dem AlkaPolP-Prozess mindestens ähnliche Produktausbeuten und -qualitäten erreicht werden. Vor allem für den Aufschluss von widerstandsfähigem Nadelholz ist der AlkaPolP-Prozess den meisten anderen Verfahren deutlich überlegen.
Nach der Konstruktion und Fertigung eines Reaktionsextruders wurden Betriebsbedingungen gefunden, mit denen Nadelholzschnitzel über mehrere Stunden hinweg in einem stabilen kontinuierlichen Prozess effektiv in alkalischem Glycerin aufgeschlossen werden konnten.
Auf der Grundlage von Literaturdaten und der durchgeführten Experimente wurde ein Gesamtprozess entworfen, der neben bereits untersuchten Verfahrensstufen auch eine Aufarbeitung des Ligninfiltrates durch eine Elektrodialyse und mehrere Destillationsschritte umfasst und eine Regeneration der Einsatzstoffe sowie eine Abtrennung der während des Aufschlusses gebildeten Carbonsäuren ermöglicht.
Die Ergebnisse dieser Arbeit bilden den Grundstein für die Weiterentwicklung des AlkaPolP-Prozesses. Es konnte gezeigt werden, dass dieser, im kontinuierlichen Betrieb durchführbare und für alle Arten von Lignocellulose geeignete, Aufschlussprozess einen vielversprechenden Ausgangspunkt für ein nachhaltiges Bioraffineriekonzept darstellt.
In the present work, the role of chemical compounds of one abundant vegetable waste, exhausted coffee, on Cr(VI), Cu(II), and Ni(II) sorption has been investigated. For this purpose, exhausted coffee was subjected to sequential extractions by using dichloromethane (DCM), ethanol (EtOH), water, and NaOH 1 %. The raw and treated biomass resulting from the extractions were used for metal ions sorption. Sorption results were discussed taking into consideration polarity and functional groups of raw and treated biomass. In general, the successive removal of extractives led to an insignificant increase in the studied metal ions sorption after DCM, EtOH, and water. The sorption results using free-extractive materials showed that metal sorption can be effectively achieved without this non-structural fraction of the sorbent. Alkaline hydrolysis destroyed in part the structural compounds of the sorbent resulting in an insignificant decrease of chromium removal while a significant increase of copper and nickel sorption was observed. The determination of elemental ratios of exhausted coffee and all treated biomass evidenced the involvement of oxygen functional groups in copper and nickel sorption. FTIR analysis confirmed the involvement of lignin moieties in the chromium sorption by exhausted coffee. As a final remark, this study shows that the sequential extraction opens new expectations to the total valorisation of lignocellulosic-based biomasses. The extractives can be removed and used as a biosource of valuable compounds, and the resulting waste can be used as a sorbent for metal ions keeping the same capacity for metal sorption as the non-extracted biomass.
The concentrations and protonation constants of the functional groups like carboxyl and phenolic hydroxyl groups in spruce bark were determined by a potentiometric acid-base titration method. The non-cellulosic carbohydrates in spruce bark were also characterized by acid methanolysis and GC, including determination of the uronic acid units, which are the key units involved in metal sorption. Sorption of metal ions to bark takes place by ion exchange, mainly by complexation to these functional groups. The sorption equilibrium time, studied by using a batch method, was approximately 5 min. The metal sorption capacity of spruce bark and the affinity order of metal ions were studied with four different metal ion mixtures using a column chromatographic method. Because a method of competition was used, concentration of metal ions adsorbed to bark depends on the metal ions present in the mixtures studied. In the sorption experiments with same metal ion mixtures, inner bark of spruce exhibited higher sorption capacity than outer bark. By combination of the results from several experiments, the following affinity order was obtained Fe3+ >> Pb2+ >> Cu2+ >> Cd2+ > Zn2+ > Ni2+ > Ba2+ > Ca2+ > Sr2+ > Mn2+ > Mg2+ >> K+ similar to Na+ similar to Li+. Bark has a great potential as an effective and inexpensive sorbent for removal of metal ions from, e.g., waste water.
Possible chemical utilization of bark requires appropriate knowledge of its composition. Extraction of valuable components before burning is an interesting option for utilization of bark. Here, Norway spruce inner and outer bark were extracted separately with a successive series of solvents of increasing polarity and the extracts, as well as the residues, were analyzed to obtain an overall picture of the bark composition.
The lipophilic extractives contained the same major components as found in wood. Inner bark contained over 10% of stilbene glucosides with piceatannol (astringenin) as the main stilbene. Tannins of the proanthocyanidin type were extracted with hot water. Further extraction with pressurized hot water at 140C or 160C yielded 11-14% of non-cellulosic polysaccharides, on original bark basis, with pectic poly-saccharides built up of arabinose, galacturonic acid and rhamnose dominating. Inner bark contained two times more cellulose than outer bark, but the opposite was true for lignin, determined as Klason “lignin”.
Among the potentially valuable components, stilbene glucosides could be extracted with water even at low temperatures, while tannins could be extracted with hot water in a second step. The pectic polysaccharides are also of potential interest and should be studied further. The amount and true chemical character of lignin is also not yet fully elucidated.
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