Retting Of Flax Research Articles

Production of efficient enzymes for flax retting by solid state fermentation withAspergillus niger

Purpose– The purpose of this paper is to study the optimum culture condition of flax-retting enzyme, and applying the enzyme liquors to retting. In addition to research the structure of flax stem in enzyme retting using scanning electron microscopy (SEM).Design/methodology/approach– The influence of cultural parameters such as moisture level, temperature, incubation time and inoculum size were evaluated with respect to polygalacturonase and xylanase yield. The structure of flax stem was revealed by SEM.Findings– The flax was retted by dilute enzyme liquors (polygalacturonase/25 U/ml, xylanase/1 U/ml), and 24-h retting period was obtained. The SEM studies revealed the removal of a large amount of non-cellulosic gummy material of flax stem in enzyme retting.Originality/value– First, flax-retting enzyme containing higher-yield polygalacturonase, lower-yield xylanase and no cellulose was yielded by SSF. Second, the composition of enzyme could meet flax retting and no damage cellulosic fibre. Finally, only low-cost wheat bran, citrus peel powder and mineral salt were employed in substrate, which could reduce the overall cost of enzyme production and flax retting.

Microwave assisted retting – A novel method of processing of flax stems

A new method for retting of flax stem was introduced by using microwave energy. The combined effect of pre-soaking, microwave volumetric heating and the non-thermal effect of microwave energy were applied in the retting of flax stem. Effective retting was observed in various combinations of pre-soaking, Microwave treatment times and microwave energy. The samples soaked for 24 and 36 h with microwave treatments of 20 min showed better retting efficiency. Fried tests, Near Infrared analysis and fibre diameter analysis were done to find out the retting efficiency. The effect of non-thermal effect of microwave in flax retting was proved experimentally. Colourimetric tests and tensile strength tests were conducted to compare the quality of fibres after microwave retting and no significant changes in the physical qualities were observed. The water released after pre-soaking was not contaminated because of less microbial activity in short duration of the entire process. In industrial point of view, this method is acceptable because of the ease of recyclability of the pre-soaked water and comparably short duration of the process.

Influence of the degree of retting of flax fibers on the tensile properties of single fibers and short fiber/polypropylene composites

The flax quality required for composite applications is not yet well established. Retting is one of the steps that are not well defined for these applications, and is a critical parameter during flax production. In this study, the influence of the degree of retting of flax on the properties of short flax fiber/polypropylene composites has been assessed. First, the degree of retting of gradually retted flax was measured by both qualitative and quantitative experimental techniques. In addition, water sorption studies were performed. Furthermore, tensile tests were carried out on both single fiber and injected composite materials. The microstructure of the composites was analyzed by scanning electron microscopy and X-ray micro-tomography. Single fiber and composite tensile properties, as well as water sorption behavior of flax fibers, were found to depend upon the degree of retting.

Linen most useful: perspectives on structure, chemistry, and enzymes for retting flax.

The components of flax (Linum usitatissimum) stems are described and illustrated, with reference to the anatomy and chemical makeup and to applications in processing and products. Bast fiber, which is a major economic product of flax along with linseed and linseed oil, is described with particular reference to its application in textiles, composites, and specialty papers. A short history of retting methods, which is the separation of bast fiber from nonfiber components, is presented with emphasis on water retting, field retting (dew retting), and experimental methods. Past research on enzyme retting, particularly by the use of pectinases as a potential replacement for the current commercial practice of field retting, is reviewed. The importance and mechanism of Ca2+ chelators with pectinases in retting are described. Protocols are provided for retting of both fiber-type and linseed-type flax stems with different types of pectinases. Current and future applications are listed for use of a wide array of enzymes to improve processed fibers and blended yarns. Finally, potential lipid and aromatic coproducts derived from the dust and shive waste streams of fiber processing are indicated.

Optimization of mannanase production by Bacillus sp. HDYM-05 through factorial method and response surface methodology

Bacillus sp. HDYM-05 was separated from flax retting liquid and identified as Bacillus cereus which was a new source of microbial mannanase. To optimize the medium components and condition of shake flask experiment for a higher mannanase production, factorial method and response surface methodology were used to obtain the maximal productivity by this species originally. The optimal medium components were: konjaku flour 8.81%, yeast extract 0.5%, NaNO3 0.5%, K2HPO4 0.5%, MgSO4·7H2O 0.02%. The optimal condition of shake flask experiment was: 75 ml medium in 500 ml flask, inoculum volume 1%, initial pH 8.0 and 140 rpm with the cultivation temperature and time at 37°C and 32.05 h, respectively. The maximum enzyme activity of Bacillus sp. HDYM-05 achieved 6777.4 U/ ml, 1.4 folds under the optimal culture conditions as compared to the initial control. Key words: Mannanase, Bacillus cereus, optimization, factorial method, response surface methodology.

Flax Retting Wastewater Part 1: Anaerobic Treatment by Using UASB Reactor

The performance of UASB (Up-flow Anaerobic Sludge Blanket) reactor was investigated in the present study for treatment of flax retting wastewater. Batch and continuous experiments on a pilot scale were designed. The initial seed for granules (bacteria acclimation) formed earlier was from municipal sewage treatment plant with VSS of 18 - 20 g/L. Batch experiments proved that the sludge retention time (SRT) was 77 days. Under steady state conditions, continuous experiments were conducted at organic loading rates (OLRs) in the range of 1.2 to8.6 kgCODs m–3·d–1, where the hy- draulic retention time (HRT) decreased from 72 to 12 hrs. The results proved that the UASB technology provides good COD removal efficiency from 64.5% to 90.5% as COD loading rate decreased and good biogas production at proper food: micro-organism (F:M) ratios.

Analysis of Bacterial Community in Water Retting of Flax*

The bacterial community structure in water retting systems of Bei'an flax in Heilongjiang,China was studied by using denaturing gradient gel electrophoresis(DGGE) and culture-dependent method,respectively.The results obtained from the culture-independent method showed that Pseudomonas and Clostridium were found the dominant genera using aerobic and anaerobic cultivation in water retting,respectively.Micrococcus and Staphylococcus were only observed within initial 16 h.The profile of DGGE fingerprints in water retting of different periods revealed that the bacterial groups group were relatively fewer.As a result,two major bands of 16S rDNA genes fragments from DGGE profiles were further eluted from gel,prior to be reamplified and sequenced.The sequences of these fragments were compared with the database of GenBank(NCBI).9 genera were identified from the water retting with the culture-dependent method.Compared with the database of GenBank,the results displayed that 11 sequences of band d shared 92%～99% homology of the known sequences(Pantoea,Bacillus,unidentified bacterium and new bacteria),while the 12 sequences of band e shared 96%～100% homology of the known sequences(Pseudomonas).This suggests that a combination of molecular and culture-dependent methods can be used to analyze and monitor the community structure of water retting effectively,and will give us more information of microorganism community structure.Fig 4,Ref 15

The environmental impacts of the production of hemp and flax textile yarn

This study aimed to quantify major environmental impacts associated with the production of hemp yarn using Life Cycle Analysis (LCA). A reference scenario of traditional hemp warm water retting was compared to: (1) bio-retting, i.e. hemp green scutching followed by water retting, (2) babyhemp, based on stand retting of pre-mature hemp, (3) dew retting of flax. Overall, neither of the alternative scenarios was unambiguously better than the reference. The impacts of the hemp reference scenario and the flax scenario were similar, except for pesticide use (higher for flax) and water use during processing (higher for hemp). Bio-retting had higher impacts than the reference scenario for climate change and energy use, due to higher energy input in fibre processing. Babyhemp had higher impacts than the reference scenario for eutrophication, land occupation and pesticide use. A reduction of the environmental impacts of hemp yarn should give priority to reduction of energy use in the fibre processing and yarn production stages and to reduction of eutrophication in the crop production phase.

The importance of time of spraying, desiccant type and harvest time on industrial fibre production from stand-retted fibre flax (Linum usitatissimum)

SUMMARYEven and successful retting of flax through application of a desiccating herbicide and stand-retting is a major constraint to increasing its incorporation in industrial products. With the release of a new form of glyphosate based on the isopropylamine (IPA) salt with biactivator (Roundup Biactive, Monsanto Ltd), a field trial was planted using three flax varieties with differing levels of ease of desiccation at the Henfaes Research Centre, University of Wales Bangor in 2004. The crop was sprayed at four different times of maturity: mid-point of flowering plus 7 days (MPF+7), MPF+14, MPF+21 or MPF+28 using two different herbicide treatments; Roundup Biactive (Monsanto PLC) or Roundup Biactive+Restore (40% ammonium sulphate, AmegA Sciences PLC). Fibre quality was assessed following retting and the ease of decortication was measured. The highest fibre yields were obtained from the MPF+28 spray date, and from the Biactive herbicide treatment. Although lower yields were recorded with the Biactive+Restore treatment, the stems were easier to decorticate. It is suggested that an early sowing date and the use of the IPA salt-based glyphosate with biactivator, and careful monitoring of the crop during the retting process, contributed to the early and successful harvest from the MPF+28 plots, allowing mature seeds as well as fibre to be harvested from the flax plants.

Easily available enzymes as natural retting agents

Easily available commercial enzymes currently have great potential in bast fibre processing and can be modified for different end uses. There are several new technologies using enzymes that are able to modify fibre parameters, achieve requested properties, improve processing results and are more beneficial to the ecology in the area of bast fibre processing and fabrics finishing. Enzymatic methods for retting of flax, "cottonisation" of bast fibres, hemp separation, and processing of flax rovings before wet spinning, etc., fall into this group of new technologies. Such enzymatic biotechnologies can provide benefits in textile, composite, reinforced plastic and other technical applications. Laboratory, pilot and industrial scale results and experiences have demonstrated the ability of selected enzymes to decompose interfibre-bonding layers based on pectin, lignin and hemicelluloses. Texazym SER spray is able to increase flax long fibre yields by more than 40%. Other enzymes in combination with mild mechanical treatment can replace aggressive and energy-intensive processing like Laroche "cottonisation". Texazym SCW and DLG pretreatments of flax rovings are presented.

Lignin deficiency in transgenic flax resulted in plants with improved mechanical properties

Flax (Linum usitatissimum L.) is a very important source of natural fibres used by the textile industry. Flax fibres are called lignocellulosic, because they contain mainly cellulose (about 70%), with hemicellulose, pectin and lignin. Lignin is a three-dimensional polymer with a high molecular weight, and it gives rigidity and mechanical resistance to the fibre and plant. Its presence means the fibres have worse elastic properties than non-lignocellulosic fibres, e.g. cotton fibres, which contain no lignin. The main aim of this study was to produce low-lignin flax plants with fibres with modified elastic properties. An improvement in the mechanical properties was expected. The used strategy for CAD down-regulation was based on gene silencing RNAi technology. Manipulation of the CAD gene caused changes in enzyme activity, lignin content and in the composition of the cell wall in the transgenic plants. The detected reduction in the lignin level in the CAD-deficient plants resulted in improved mechanical properties. Young's modulus was up to 75% higher in the generated transgenic plants (CAD33) relative to the control plants. A significant increase in the lignin precursor contents and a reduction in the pectin and hemicellulose constituents was also detected. A decrease in pectin and hemicellulose, as well as a lower lignin content, might lead to improved extractability of the fibres. However, the resistance of the transgenic lines to Fusarium oxysporum was over two-fold lower than for the non-transformed plants. Since Fusarium species are used as retting organisms and had been isolated from retted flax, the increased sensitivity of the CAD-deficient plant to F. oxysporum infection might lead to improved flax retting.

Mid-to late-Holocene land-use change and lake development at Dallund S0, Denmark: synthesis of multiproxy data, linking land and lake

Multiproxy palaeoecological data for lake Dallund S0, Denmark, were synthesized to explore the link between changes in the terrestrial environment (from pollen, and sediment physical properties) with those in the aquatic environment (from diatom, macrofossil, zooplankton and Pediastrum data) since the introduction of agriculture c. 6000 years ago. The lake was relatively insensitive to catchment disturbance during the Neolithic (3870-1700 BC) and Early Bronze Age (1700-1000 BC) periods but was dramatically impacted by environmental changes associated with a major deforestation phase at the transition from the Late Bronze Age (1000-500 BC) to the Pre-Roman Iron Age (500 BC-AD 0). A major eutrophication of the lake took place as a result of a changing agricultural system and also the retting of flax and hemp during the Mediaeval period (AD 1050-1536). Analyses of the data sets representing the terrestrial and aquatic environments demonstrate that human activities over thousands of years have not only impacted and shaped the Danish landscape but have also played a major role in lake development.

The active component in the flax-retting system of the zygomycete Rhizopus oryzae sb is a family 28 polygalacturonase

The zygomycete Rhizopus oryzae sb is a very efficient organism for retting of flax, the initial microbiological step in the process of making linen. An extracellular polygalacturonase, when isolated could perform retting, and therefore probably is the key component in the retting system of R. oryzae. This was purified and characterized. The purified enzyme has a molecular mass of 37,436 Da from mass spectrometric determination, an isoelectric point of 8.4, and has non-methylated polygalacturonic acid as its preferred substrate. Peptide sequences indicate that the enzyme belongs to family 28, in similarity with other polygalacturonases (EC. 3.2.1.15). It contains, however an N-terminal sequence absent in other fungal pectinases, but present in an enzyme from the phytopathogenic bacterium Ralstonia solanacearum. The biochemical background for the superior retting efficiency of R. oryzae sb is discussed.

Microscopy to Evaluate Retting of Flax and Flax Fibers

Microscopy to Evaluate Retting of Flax and Flax Fibers

The use of FT‐IR microspectroscopic mapping to study the effects of enzymatic retting of flax (Linum usitatissimum L) stems

AbstractFourier transform infrared (FT‐IR) microspectroscopic mapping was investigated as a tool to study the effects of enzymatic retting of flax stems. The FT‐IR technique permitted the elucidation of the relative loss or changes in the distribution of key chemical components after treatment with enzymes or enzyme/chelator mixtures in association with visible changes in structure. Cross‐sections of Ariane flax stems were treated with SP 249 (a pectinase‐rich enzyme mixture from Novo Nordisk) at 0.5, 0.7 or 1.0 ml l−1 concentration in pH 5 acetate buffer for 6 h at 40 °C. Flax stems treated with 0.5 or 0.7 ml l−1 SP 249 and 50 mM oxalic acid as a chelator were also investigated by the technique. The results indicated that treatment with 0.5 ml l−1 SP 249 alone was ineffective in releasing the fibre bundles from the surrounding tissue, but the release was increased by the addition of 50 mM oxalic acid as a likely chelator for the cations of pectate salts. However, the IR spectra of the bundles indicated that an insoluble oxalate salt remained on the tissue after this treatment. Increasing the concentration of SP 249 to 0.7 ml l−1 plus 50 mM oxalic acid was effective in releasing the fibre bundles and generating some ultimate fibres with no detectable oxalate expectate salt residues. Increasing the SP 249 concentration to 1.0 ml l−1 without using oxalic acid was effective in separating the fibre bundles into ultimate (individual) fibres, leaving no pectate salt residue and only a trace of pectic esters and/or acids. The use of infrared mapping, or so‐called chemical imaging, is shown to have advantages over visible imaging alone in that it can detect and locate the chemical species present after each treatment in relation to the anatomical features of the flax stem. This analytical tool shows promise as a technique by which to study the effects of enzymatic treatment of natural fibre materials.Published in 2002 for SCI by John Wiley & Sons, Ltd

Chelating Agents and Enzyme Retting of Flax

Chelators added to pectinase-rich enzyme mixtures increase the efficiency of enzyme retting of flax. The multitude of available chelators requires research to optimize enzyme retting for cost and fiber quality, Of several chelators tested, ethylenediaminetetraacetic acid (EDTA) is the most effective in sequestering calcium from solution, with substantial activity even at pH 4 or 5. Phosphate is also effective, but only at high pH. EDTA and Mayoquest 200, a commercial product with ∼37% EDTA, in combination with Viscozyme L or Lyvelin, commercial enzymes with polygalacturonase activities, yield high Fried test scores, indicating efficient separation of fibers from core tissues. Neither chelator nor enzyme at the levels tested alone effectively rets flax at a pH of around 5. In contrast, EDTA at 20 mmol/L levels and alkaline pH yields high Fried test scores. The addition of BioPrep, a commercial pectate lyase, does not influence retting measured by the Fried test with EDTA at alkaline pH, but the enzyme does improve retting with the weaker chelator sodium tripolyphosphate. The quality of fibers, as determined by the yield of fine fibers obtained by passing retted flax through the Shirley analyzer, is substantially greater with EDTA plus Viscozyme at pH 5 than alkaline chemical retting with EDTA, sodium tri polyphosphate, or sodium oxalate without enzyme. EDTA is the most effective chelator at acidic pH levels for stimulating flax retting by various commercial pectinase-rich enzyme mixtures. However, other less expensive candidates require additional study for more cost-effective formulations and applicable fiber properties.

Retting Flax with Endopolygalacturonase from Rhizopus oryzae

Retting, which is the process of separating fibers from nonfiber tissues in bast plants, is the major problem in processing flax for linen, and new methods, especially enzyme retting, are being pursued to overcome this problem. Production of an endopolygalact uronase (EPG) from Rhizopus oryzae, which was isolated earllir from dew retted flax, is optimized, and the enzyme is subsequently purified and characterized. Purified EPG is evaluated for its efficiency in retting flax alone and in combination with other cell wall degrading enzymes. The Fried test, light and scanning electron microscopy, and fiber strength and fineness properties indicate that EPG alone (without additional enzymes) plus chelator gives retting efficiencies similar to previously used enzyme mixtures. The addition to EPG of pectin methyl esterase, pectin lyase. xylanase, or endoglucanase does not improve retting efficiency or strength and fineness properties of the retted flax fibers over EPG alone. Spray enzyme retting of a 50 g flax sample with EPG/chelator formulation produces retted flax fibers with strength and fineness properties similar to those retted with a commercial enzyme mixture. Our results indicate that EPG is of paramount importance in flax retting, and they suggest an opportunity, through cloning technology, to produce a consistently effective but simplified enzyme formulation for flax retting.

Plant factors influencing enzyme retting of fiber and seed flax.

Retting, which is the microbial activity through which bast fibers are released from nonfiber tissues, is the limiting factor in flax processing. The objective of this work is to identify chemical and structural characteristics in a variety of fiber and seed flax types that influence enzyme retting in a recently developed method. Analyses of flax retted in a series of tests, including two enzyme rettings in some cases, indicated that lignin did not limit the separation of fibers from shive and showed that pectinases in enzyme-retting mixtures could ret fiber and seed flax. However, mature stems, such as that in flax produced for seed, had greater amounts of cutin and wax in the cleaned fiber product, suggesting that the cuticle could be a greater antiquality factor in seed versus fiber flax. With seed flax, the fraction of finer fibers produced during retting was significantly lower than with fiber flax. Results indicated that enzyme retting could be used to obtain flax fibers from seed flax stem residues and add value to this agricultural material.

Polygalacturonase is the key component in enzymatic retting of flax

Seven commercial enzyme mixtures were tested for their ability to perform retting of flax (i.e. to separate flax fibers by partly removal of middle lamella) and were assayed for hydrolysis of xylan, cellulose and four kinds of pectin. The only activity that showed correlation to the ability to perform retting was the degradation of low esterfied pectin. A purified Aspergillus niger polygalacturonase was also shown to be able to perform retting. From this data it is hypothesized that degradation of the smooth regions (i.e. non-methylated polygalacturonase) in the middle lamella pectin is the most important step in enzymatic retting.

Use of spectral window preprocessing for selecting near-infrared reflectance wavelengths for determination of the degree of enzymatic retting of intact flax stems

A near-infrared reflectance (NIRR) method suitable for air-dried intact flax stems was developed for determination of Fried's test degree-of-retting scores. Performance statistics for preferred wavelength sets from 2 to 12 wavelengths are reported, and 7-, 9-, or 12-wavelength models are recommended. The wavelength sets are taken from the 1432- to 2468-nm spectral range. Calibration samples were prepared by retting flax stems for various lengths of time in an enzyme/chelator solution. Spectral properties of specimens were measured under varying conditions of hydration, stem orientation, and optical geometry, and calibration models were constructed to be insensitive to these effects. Root mean squared model errors were estimated by full cross-validation (RMSECV) that was modified to ensure the independence of each test sample relative to its calibration set. For the 12-wavelength model, the correlation ( R 2) between predicted and measured is 0.946 and RMSECV is 0.20 for smoothed Fried's test scores spanning the four visual score levels, 0 to 3, from under-to over-retted. The 12-wavelength NIRR method has lower error than Fried's test scores produced by one observer in a single-blind experiment, where the root mean squared repeatability error is estimated to be 0.25. Furthermore, even the smallest wavelength set has excellent success in classifying enzyme-retted flax stems as either under- or over-retted. Wavelength sets were determined by a novel procedure that first located representative spectral windows by testing the performance of all possible spectral ranges, and then selected the optimum combinations of wavelengths from each window. It is shown that this procedure was able to find multiple linear regression wavelength models that substantially outperform full-spectral partial least squares regression models of similar dimensionality, and furthermore, that the method facilitates observation of the most relevant spectral variations.