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Enzyme-Retted Flax Using Different Formulations and Processed Through the USDA Flax Fiber Pilot Plant Danny E. Akin ab; Jonn A. Foulk cd; Roy B. Dodd e; Helen H. Epps f a US Department of Agriculture, Richard B. Russell Agricultural Research Center, Athens, GA, USA b US Department of Agriculture, Agricultural Research Service, Athens, GA, USA c US Department of Agriculture, Cotton Quality Research Station, SC, USA d US Department of Agriculture, Agricultural Research Service, Clemson, SC, USA e Department of Agricultural and Biological Engineering, Clemson University, Clemson, SC, USA f Department of Textiles, Merchandising & Interiors, University of Georgia, Athens, GA, USA Online Publication Date: 08 August 2006
To cite this Article Akin, Danny E., Foulk, Jonn A., Dodd, Roy B. and Epps, Helen H.(2006)'Enzyme-Retted Flax Using Different
Formulations and Processed Through the USDA Flax Fiber Pilot Plant',Journal of Natural Fibers,3:2,55 — 68 To link to this Article: DOI: 10.1300/J395v03n02_04 URL: http://dx.doi.org/10.1300/J395v03n02_04
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Enzyme-Retted Flax Using Different Formulations and Processed Through the USDA Flax Fiber Pilot Plant Danny E. Akin Jonn A. Foulk Roy B. Dodd Helen H. Epps
Danny E. Akin is affiliated with the Richard B. Russell Agricultural Research Center, P.O. Box 5677, Agricultural Research Service, US Department of Agriculture, Athens, GA 30604 USA (E-mail:
[email protected]). Jonn A. Foulk is affiliated with the Cotton Quality Research Station, P.O. Box 792, Agricultural Research Service, US Department of Agriculture, Clemson, SC 29678 USA (E-mail:
[email protected]). Roy B. Dodd is affiliated with the Department of Agricultural and Biological Engineering, Clemson University, Clemson, SC 29634 USA (E-mail: rdodd@clemson. edu). Helen H. Epps is affiliated with the Department of Textiles, Merchandising & Interiors, University of Georgia, Athens, GA 30602 USA (E-mail:
[email protected]). The authors gratefully acknowledge Zdenìk Šprynar, Czech Flax Machinery, MGín, Czech Republic, for design and manufacture of the equipment. Appreciation is expressed to Anakul Watthanasuk, Brad Reed, Luanne Rigsby, and Tomas Ayala-Silva for excellent technical support in processing and testing of fibers. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S.D.A. of any product or service to the exclusion of others that may be suitable. [Haworth co-indexing entry note]: “Enzyme-Retted Flax Using Different Formulations and Processed Through the USDA Flax Fiber Pilot Plant.” Akin, Danny E. et al. Co-published simultaneously in Journal of Natural Fibers (Food Products Press, an imprint of The Haworth Press, Inc.) Vol. 3, No. 2/3, 2006, pp. 55-68; and: Biotechnology in Textile Processing (ed: Georg M. Guebitz, Artur Cavaco-Paulo, and Ryszard Kozlowski) Food Products Press, an imprint of The Haworth Press, Inc., 2006, pp. 55-68. Single or multiple copies of this article are available for a fee from The Haworth Document Delivery Service [1-800-HAWORTH, 9:00 a.m. 5:00 p.m. (EST). E-mail address:
[email protected]].
Available online at http://www.haworthpress.com/web/JNF © 2006 by The Haworth Press, Inc. All rights reserved. doi:10.1300/J395v03n02_04
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BIOTECHNOLOGY IN TEXTILE PROCESSING
SUMMARY. Mature Ariane flax was retted with various proportions of the commercial enzyme mixture Viscozyme L (0.05, 0.1, 0.2, and 0.3% of product as supplied) and ethylenediaminetetraacetic acid (4, 7, and 18 mM) from Mayoquest 200. Retted material was then cleaned through the USDA Flax Fiber Pilot Plant (Flax-PP) consisting of the following: 9-roller crushing colander, top shaker, scutching wheel, and 5-roller grooved colander. To simulate cottonization of fiber for use in textiles, the Flax-PP-cleaned fiber was passed 1 ⫻ through a Shirley Analyzer. Fiber yields and properties (strength, elongation, fineness, and color), which were determined for the various processing stages, were influenced by various formulations and by processing stage. For this flax sample, 0.05% Viscozyme plus 18 mM EDTA produced the highest yield of Flax-PP and Shirley-cleaned fibers, strong fine fibers of light color, and the strongest coarse fibers from Shirley by-product material. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-HAWORTH. E-mail address: Website: © 2006 by The Haworth Press, Inc. All rights reserved.]
KEYWORDS. Flax, viscozyme, Mayoquest 200, EDTA, Flax-PP, pilot plant, retting, cleaning
INTRODUCTION Flax (Linum usitatissimum L.) has provided high quality fibers used in linen for millennia (Borlund, 2002; Hamilton, 1986; Sharma and Van Sumere, 1992). Despite the fact that cotton has preempted flax as the premier natural fiber for textiles, linen is valued for its distinctive appearance and comfort and still maintains a share of the luxury textile market. In addition to 100% flax products, blends with other fibers periodically appear as part of the fashion trends or for niche markets (Borland, 2003). Particularly, moisture management and air permeability are improved with increasing amounts of flax in cotton blends (Annis, 2000; Foulk et al., 2002). In addition to apparel, flax provides fibers for other industrial applications, including nonwoven fabrics, composites, and specialty papers (van Dam et al., 1994; Berglund, 2002). Tow, the by-product of the long line linen production systems, supplies flax fiber for short staple textile spinning and many non-apparel uses. The current interest in using natural fibers in composites, even as replacement for glass fiber (Hagstrand
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and Oksman, 2001), has focused primarily on the bast plants, such as flax, as primary sources. Total fiber from the entire stem, rather than tow from long-line operations, could provide a source for many textile and industrial applications. The collection of non-aligned, non-uniform fibers from the entire stem permits use of many non-traditional sources of flax fiber, such as the vast resources of linseed straw (Domier, 2002) that can be harvested and handled with traditional on-farm equipment (Foulk et al., 2002). Bast fibers are produced within the cortical regions of the stems (Van Sumere, 1992). The fibers exist as tightly bound bundles attached to and encircling the woody, core cells (i.e., shives) and surrounded by a formidable cuticularized epidermis (Akin, 2003). Considerable effort and costs are required to process and clean flax fibers of the shive and other non-fiber components (Sultana, 1992). In Europe, work has been done to develop more efficient decortication systems to supply non-linen flax fiber in large amounts for composites and nonwoven industries (Gilbertson, 1996; Z. Sprynar, personal communication). In any such cleaning system, the source of flax and degree of retting affects the processing operation and quality of fibers produced. It is well established that the quality of retting is a major influence on yield and quality of flax fibers (Van Sumere, 1992). For several decades, flax for textile uses has been dew-retted by indigenous microorganisms that colonize and partially degrade plant components and thus free fibers from other tissues. Dew-retting results in fibers at times with inconsistent quality, and improved retting methods have been sought for many years (Sharma and Van Sumere, 1992). In investigations of enzymes for this purpose, pectinase and pectinase-rich enzyme mixtures were shown to effectively extract fibers (Akin et al., 2000a; Van Sumere, 1992). Pilot plant studies have shown that commercial pectinase-rich mixtures can effectively ret fibers with high quality. For example, in a side-by-side test in Europe in the 1980s (Sharma, 1987), flax stems (80 kg) submerged in a pectinase-rich mixture (SP 249 from Novo Nordisk) at 0.3% v/v (11:1 liquid/fiber ratio) resulted in fibers of equal yield and quality to that from water- or chemical-retting. In the U.S., flax stems (12 kg) were crimped and soaked briefly in formulations having various proportions of the enzyme and chelator components to test new retting methods and formulations; fibers of reasonable properties were produced, and variations occurred with different formulations (Akin et al., 2001). Despite considerable research on enzyme-retting, a commercial method does not exist. Cost, lack of standards, and other factors, includ-
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ing a relatively small textile market share, have maintained the present methods for production and processing of flax for textiles. Growth in the use of flax and other natural fibers in a broadening bio-based economy, however, created interest for new processes for retting and cleaning flax fiber by the most efficient means for uniform quality fibers. Formidable barriers still remain for discovering the most efficient enzyme/chelator formulations and for the integration of retting and cleaning for optimal yield and properties of the fibers. Enzymes, because of specific and directed activities, can provide fibers with tailored properties for industrial uses. Research presented herein addresses recent work on the use of diverse formulations for retting flax integrated with mechanical cleaning through a recently established USDA Flax Fiber Pilot Plant. Fibers from various stages of the processing systems were compared for yield, strength, elongation, fineness, and color. MATERIALS AND METHODS Sample and Retting The flax sample and retting conditions were described previously (Akin et al., 2002). Briefly, the cultivar ‘Ariane’ was grown to full seed maturity as a winter crop in South Carolina and harvested in May, 1999. Plants were dried in the field without obvious microbial weathering. Flax stems were prepared for enzyme-retting as described for the SER method (Akin et al., 2000a), except the plants were soaked rather than sprayed with formulation. Viscozyme L (Novozymes North America, Inc, Franklinton, NC), a pectinase-rich enzyme mixture, was used at 0.05, 0.1, 0.2, and 0.3% of the product as supplied. Mayoquest 200 (Callaway Chemical Co., Smyrna, GA), which is a 38% solution of the tetrasodium salt of EDTA at alkaline pH, was adjusted to pH 5.0 with HCl and used as a chelator in aqueous solutions of 0.4% (3.65 mM), 0.7% (7.3 mM), or 1.8% (18.25 mM) levels. Duplicate samples of about 5.5 kg each of crimped flax stems were soaked with ca 40 liters of each of the 12 retting formulations and rotated in a sealed container for 2 min. Enzyme-soaked flax was then placed in an insulated chamber, covered with burlap soaked in enzyme formulation to retain humidity, and incubated at 40°C for 24 h. Retted flax was then washed with 2 changes of 110 liters of tap water for 5 min each and dried in the chamber at 50°C. About 4 kg of dried retted material was produced from the original 5.5
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kg of straw. A portion of this material (about 80 g) had been used in a previous laboratory study (Akin et al., 2002).
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Mechanical Cleaning The enzyme-retted, dried flax was processed through the newly established USDA Flax Fiber Pilot Plant (Flax-PP) based on the commercial ‘Unified Line.’ This cleaning system was originally produced by Ceskomoravsky len, Humpolec, Czech Republic, and had been tested earlier with enzyme-retted flax (Akin et al., 2001). The Flax-PP has been described (Akin et al., 2004) and consists of four modules: (1) 9-roller colander to crush the flax stems and separate shive and fiber, (2) top shaker to align, open, and fluff fiber mats and remove loosened shive, (3) scutching wheel to aggressively stroke, refine, and shorten flax, and (4) 5-roller colander with grooved surfaces to remove fine shive particles. All samples were processed in the following order: 9-roller colander, top shaker, scutching wheel, top shaker, 5-roller colander, and top shaker. Samples were passed once through the sequence of modules as listed above, except for 2 passes through the last top shaker stage. Flax-PP cleaned fibers were then passed one time through the Shirley Analyzer (SDL America, Charlottesville, North Carolina, USA), which simulated systems to further clean and refine fibers for use in textiles. Both Shirley-cleaned fibers as well as coarse fibers not processed through the Shirley Analyzer (termed Shirley-by-product) were collected and analyzed. Fiber Properties Flax-PP-cleaned, Shirley-cleaned, and Shirley by-product fibers were evaluated for strength and elongation by Stelometer (ASTM, 1999a) and fineness by a modified micronaire (air flow) method (ASTM, 1999b) as described (Akin et al., 2002). Samples were also measured for lightness, red/green, and yellow/blue color using CIELAB methods as described (Akin et al., 2000b; Epps et al., 2001). One-way analysis of variance was used to assess differences, using least square differences at P ⱕ 0.05. RESULTS Yields of fiber from the various enzyme-chelator formulations are shown after cleaning through the Flax-PP and then through the Shirley
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Analyzer (Table 1). After Flax-PP cleaning, fiber yield ranged from 22.8 to 27.4%, averaging 25.2 ± 1.2% of initial straw weight. Fiber yield was not different (P > 0.05) for the averages from the three chelator levels (including all enzyme levels) or for the averages from the four enzyme levels (including all chelator levels) (averages not shown in Table 1). Similar levels of fiber were extracted by the Flax-PP regardless of retting formulation. Shirley cleaning extracted the finer fibers from Flax-PP cleaned material (Table 1). Fine fiber yield ranged from 12.0 to 21.9% of the fiber cleaned by the Flax-PP, indicating variations in retting effectiveness with different formulations. Yields were not statistically different (P > 0.05) among chelator levels (including all enzyme levels) or enzyme levels (including all chelator levels). Yields, however, tended to increase with the higher levels of chelator and levels of enzyme, with highest values at 18 mM EDTA (19.7 ± 1.6) and 0.3% Viscozyme (19.9 ± 1.0). Total fine fiber yield, which was calculated by multiplying the Flax-PP-cleaned fiber yield ⫻ the Shirley-cleaned fiber yield (Table 1), ranged from 3.1 to 6.0% of straw, with an overall average of 4.6 ± 0.8%. This low value from a 1 ⫻ Shirley-cleaning is not representative of total fine fiber that would be extracted, but the values are used provide a comparison of the formulations using this method. TABLE 1. Effect of enzyme formulations on flax fiber yield at different cleaning stages Treatment Viscozyme EDTA (%) (mM)
------------------------------------------------- Yield ------------------------------------------------Flax-PP cleaneda Shirley-cleaned 1⫻ Total Fine Fiberb (% straw) (% Unified Line-cleaned fiber) (% straw)
0.05 0.1 0.2 0.3
4 4 4 4
25.3 ± 1.8 bc 25.2 ± 0.8 bc 25.3 ± 0.7 bc 25.1 ± 0.3 bc
12.0 ± 2.1 a 14.7 ± 0.2 a 19.9 ± 0.8 a 21.0 ± 2.5 a
3.1 ± 0.8 e 3.7 ± 0.1 de 5.0 ± 0.1 abc 5.3 ± 0.6 ab
0.05 0.1 0.2 0.3
7 7 7 7
26.6 ± 1.1 ab 26.1 ± 0.7 abc 24.2 ± 0.4 cd 22.8 ± 0.2 d
15.6 ± 3.1 a 19.7 ± 0.4 a 15.9 ± 0 a 19.0 ± 2.3 a
4.2 ± 0.6 bcde 5.2 ± 0.2 abcd 3.9 ± 1.1 bcd 4.4 ± 0.5 bcde
0.05 0.1 0.2 0.3
18 18 18 18
27.4 ± 1.3 ab 25.2 ± 1.0 bc 25.8 ± 0.8 abc 24.4 ± 0.4 cd
21.9 ± 2.1 a 19.1 ± 5.1 a 18.0 ± 1.0 a 19.6 ± 1.4 a
6.0 ± 0.3 a 4.8 ± 1.1 abcd 4.7 ± 0.1 bcd 4.8 ± 0.3 abcd
aEnzyme-retted straw processed through the USDA Flax Fiber Pilot Plant (see text for sequence). bCalculated as a % of initial straw weight by multiplying the % of fiber from the Flax-PP-cleaned times the amount from Shir-
ley-cleaning (one pass only). This low yield is from experimental systems and is used for comparisons of retting formulations. The value does not represent yields available from commercial systems. a,b,c,d,e Values within columns with different letters differ at P ⱕ 0.05. Average and standard deviation for duplicate samples each treatment.
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Fiber properties of strength, elongation, fineness, and color are shown for enzyme-retted flax cleaned through the Flax-PP (Table 2). Fiber strength was the property most influenced by retting formulations. Fiber strength was reduced with increasing chelator levels (within any one enzyme level); average values for the three chelator levels ranged from 33.6 to 20.8 g/tex but were not different (P > 0.05) due to high variations. Similarly, fiber strength tended to decline with increased Viscozyme levels within each chelator level. All fibers were coarse after Flax-PP cleaning, with most showing values of > 8, which is off scale with the measuring system used. No significant differences were noted for lightness or yellow/blue color of the fibers. Differences (P < 0.05) for α (red color) were due to chelator level rather than enzyme level, with fiber retted with 7 or 18 mM EDTA redder than those retted with 4 mM. Properties of the finer, Shirley-cleaned fibers from enzyme-retting are shown in Table 3. Strength was not changed due to chelator alone, but increased Viscozyme level (regardless of chelator level) reduced strength. Elongation was low and similar among treatments. Fineness was similar among treatments, but fiber tended to be finer for the 0.2 and 0.3% enzyme levels. No differences (P > 0.05) occurred for lightTABLE 2. Properties of flax fibers enzyme-retted with various formulations and cleaned by the Flax-PP CIELAB colorc
Treatment Viscozyme (%)
EDTA (mM)
Strengtha (g/tex)
Elongationa (%)
Finenessb (air flow)
L*
a*
b*
0.05 0.1 0.2 0.3
4 4 4 4
52.9 ± 7.3 a 33.1 ± 1.4 bc 23.3 ± 3.4 cde 25.2 ± 5.3 bcde
0.78 ± 0.32 a 0.69 ± 0.45 a 0.45 ± 0.35 a 0.52 ± 0.26 a
8+ 8+ 8+ 8+
62.1 ± 1.5 a 62.3 ± 0.6 a 62.8 ± 0.3 a 62.9 ± 0.1 a
5.5 ± 0.2 de 5.6 ± 0.1 cde 5.2 ± 0.3 e 5.3 ± 0.1 e
24.9 ± 0.4 a 25.0 ± 0.1 a 24.1 ± 0.8 a 24.1 ± 0.0 a
0.05 0.1 0.2 0.3
7 7 7 7
34.3 ± 4.4 b 31.7 ± 7.4 bcd 24.3 ± 0.1 bcde 21.4 ± 9.5 de
0.29 ± 0.12 a 0.45 ± 0 a 0.41 ± 0.06 a 0.49 ± 0.06 a
8+ 8+ 8+ 7.7 ± 0.4
62.4 ± 1.0 a 61.6 ± 0.3 a 62.6 ± 1.0 a 61.3 ± 1.1 a
5.9 ± 0.3 bcd 5.9 ± 0.3 bcd 5.9 ± 0.2 bcd 6.1 ± 0.2 ab
25.7 ± 1.2 a 25.1 ± 0.4 a 24.7 ± 0.1 a 25.3 ± 0.4 a
0.05 0.1 0.2 0.3
18 18 18 18
24.1 ± 4.2 bcde 21.6 ± 1.0 de 20.9 ± 3.8 e 16.5 ± 3.7 e
0.42 ± 0.07 a 0.24 ± 0.06 a 0.28 ± 0 a 0.45 ± 0.11 a
8+ 8+ 8+ 8+
62.0 ± 0.6 a 62.8 ± 0.4 a 63.5 ± 0.1 a 63.3 ± 1.3 a
6.5 ± 0.4 a 6.0 ± 0.1 bc 5.9 ± 0.2 bcd 6.2 ± 0.2 ab
25.7 ± 0.5 a 25.0 ± 0.1 a 25.1 ± 0.2 a 25.4 ± 0.2 a
a Six values were obtained for each duplicate sample by Stelometer. bAt least three values were obtained for each duplicate sample using a modified micronaire system of 5 g. Since the highest
reading for this method is 8, 8+ means the samples were very coarse and outside the range of the method. cThree readings for each of 5 specimens were obtained for each duplicate sample. a,b,c,d,e Values within columns with different letters differ at P ⱕ 0.05. Average and standard deviation for duplicate samples each treatment.
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TABLE 3. Properties of flax fibers enzyme-retted with various formulations and cleaned by the Flax-PP and then with the Shirley analyzer
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Treatment
CIELAB color
Viscozyme (%)
EDTA (mM)
Strength (g/tex)
Elongation (%)
Fineness (air flow)
L*
a*
b*
0.05 0.1 0.2 0.3
4 4 4 4
23.9 ± 3.4 a 17.5 ± 0.2 bcde 13.3 ± 0.6 e 12.0 ± 1.3 e
1.08 ± 0.35 a 1.09 ± 0.12 a 0.92 ± 0.12 a 0.67 ± 0 a
6.9 ± 1.5 a 6.7 ± 0.4 a 6.5 ± 0.2 a 6.1 ± 0.3 a
67.5 ± 3.4 a 68.5 ± 0.3 a 68.1 ± 1.8 a 68.6 ± 0.2 a
4.1 ± 0.0 cde 3.8 ± 0.3 e 4.2 ± 0.5 cde 4.0 ± 0.8 de
22.2 ± 0.0 a 21.5 ± 0.8 a 22.0 ± 0.2 a 21.7 ± 0.1 a
0.05 0.1 0.2 0.3
7 7 7 7
19.3 ± 0.4 abcd 22.4 ± 0.4 ab 16.6 ± 2.3 cde 15.3 ± 3.3 de
1.09 ± 0.12 a 0.84 ± 0.23 a 0.84 ± 0.23 a 1.00 ± 0 a
7.3 ± 0.2 a 7.1 ± 0.2 a 5.3 ± 0.8 a 5.7 ± 0.1 a
68.0 ± 0.8 a 67.3 ± 0.8 a 69.7 ± 0.5 a 65.5 ± 0.4 a
4.5 ± 0.2 bcd 4.5 ± 0.1 bc 4.1 ± 0.0 cde 4.8 ± 0.2 ab
22.8 ± 0.1 a 22.4 ± 0.6 a 21.6 ± 0.1 a 22.3 ± 0.6 a
0.05 0.1 0.2 0.3
18 18 18 18
24.5 ± 6.0 a 21.6 ± 3.0 abc 20.1 ± 1.4 abcd 16.9 ± 0.6 bcde
1.09 ± 0.12 a 0.92 ± 0.12 a 0.84 ± 0.23 a 0.58 ± 0.35 a
6.4 ± 0.1 a 6.2 ± 0.1 a 6.1 ± 0.3 a 6.4 ± 0.1 a
66.6 ± 0.6 a 69.2 ± 1.3 a 70.0 ± 0.4 a 68.6 ± 0.3 a
5.0 ± 0.3 a 4.3 ± 0.0 bcd 4.5 ± 0.2 bcd 4.8 ± 0.1 ab
22.3 ± 0.4 a 21.8 ± 0.1 a 22.0 ± 0.1 a 22.6 ± 0.1 a
aSix values were obtained for each duplicate sample by Stelometer. bAt least three values were obtained for each duplicate sample using a modified micronaire system of 5 g. cThree readings for each of 5 specimens were obtained for each duplicate sample.
a,b,c,d,e Values within columns with different letters differ at P ⱕ 0.05. Average and standard deviation for duplicate samples each treatment.
ness or yellowness; redness increased with chelator, but not with enzymes, and was significantly higher (P < 0.05) for 7 and 18 mM levels. Properties of the Shirley by-product fibers are shown in Table 4. As expected, these fibers were too coarse to be measured by the airflow method, as the value of 8 is off-scale. Fiber strength was less (P < 0.05) with 4 mM EDTA (average of 14 ± 2 for all enzyme levels), while strength was higher at both 7 and 18 mM (21 ± 3 and 24 ± 5 g/tex, respectively). The Shirley Analyzer removed a small portion of the finer and weaker fibers, with a slightly greater amount of fibers removed at higher levels of both chelator and enzyme. The Shirley by-product from the treatments with the higher levels of enzyme and chelator, therefore, contained coarser, stronger fibers. Still, fiber strength was reduced with increased enzyme proportions within each chelator level, as had occurred with the Flax-PP and Shirley-cleaned fibers. Color was similar (P > 0.05) among treatments for lightness and yellowness, and redness was higher (P < 0.05) with 7 and 18 mM EDTA, regardless of enzyme level. DISCUSSION Chelators at high pH previously have been used to ret flax (Sharma, 1987). Likely, the destabilization of pectin molecules by removal of the
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TABLE 4. Properties of Shirley by-product flax fibers enzyme-retted with various formulations and cleaned by the Flax-PP
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Treatment
CIELAB color
Viscozyme (%)
EDTA (mM)
Strength (g/tex)
Elongation (%)
Fineness (air flow)
L*
a*
b*
0.05 0.1 0.2 0.3
4 4 4 4
14.5 ± 1.3 def 16.0 ± 2.6 def 13.5 ± 0.2 ef 11.9 ± 0.1 f
1.00 ± 0 a 0.94 ± 0.09 a 1.17 ± 0.23 a 1.17 ± 0 a
8+ 8+ 8+ 8+
64.5 ± 2.2 a 64.3 ± 0.4 a 65.0 ± 0.8 a 64.4 ± 0.2 a
5.1 ± 0.2 d 5.1 ± 0.0 d 5.1 ± 0.1 d 5.3 ± 0.2 cd
24.4 ± 0.3 a 24.1 ± 0.0 a 24.1 ± 0.1 a 24.4 ± 0.8 a
0.05 0.1 0.2 0.3
7 7 7 7
23.4 ± 6.5 bc 22.1 ± 0.6 bc 19.2 ± 0.4 bcde 17.5 ± 0.6 cdef
1.09 ± 0.12 a 1.17 ± 0 a 1.17 ± 0.23 a 1.42 ± 0.12 a
8+ 8+ 8+ 8
64.6 ± 0.2 a 64.2 ± 0.1 a 66.3 ± 1.3 a 63.3 ± 1.1 a
5.5 ± 0.2 bcd 5.7 ± 0.2 bc 5.2 ± 0.4 d 5.9 ± 0.4 ab
25.0 ± 0.5 a 25.0 ± 0.5 a 23.6 ± 0.8 a 24.9 ± 0.6 a
0.05 0.1 0.2 0.3
18 18 18 18
31.2 ± 5.0 a 23.6 ± 2.3 b 22.2 ± 2.2 bc 20.1 ± 0.4 bcd
1.09 ± 0.12 a 1.34 ± 0.47 a 1.17 ± 0.47 a 0.92 ± 0.12 a
8+ 8+ 8+ 8+
64.1 ± 0.6 a 65.6 ± 0.4 a 65.4 ± 0.1 a 65.6 ± 0.5 a
6.3 ± 0.1 a 5.7 ± 0.1 bc 5.8 ± 0.2 b 5.8 ± 0.1 b
25.5 ± 0.2 a 24.3 ± 0.6 a 24.7 ± 0.8 a 24.6 ± 0.1 a
aSix values were obtained for each duplicate sample by Stelometer. bAt least three values were obtained for each duplicate sample using a modified micronaire system of 5 g. Since the highest reading for this method is 8, 8+ means the samples were very coarse and outside the range of the method. cThree readings for each of 5 specimens were obtained for each duplicate sample. a,b,c,d,e Values within columns with different letters differ at P ⱕ 0.05. Average and standard deviation for duplicate samples each treatment.
bridging Ca++ (Sakai et al., 1993) resulted in loosening of fibers. Henriksson et al. (1997) showed that including calcium chelators such as oxalic acid or EDTA with enzymes, and at pHs optimal for enzymes, reduced the amount of enzyme needed for retting by about 50 fold. Adamsen et al. (2002a,b) evaluated several chelator types (e.g., aminopolycarboxylic acids, phosphonic acids, and polycarboxylic acids) potentially useful in enzyme-retting and that differed in cost. They found that EDTA was by far the most effective at binding Ca++, particularly at pHs required for enzyme activity, i.e., pH 5 to 6. The pectinase-rich enzyme mixture, Viscozyme L, a commercial product similar to Flaxzyme (Van Sumere, 1992), effectively separated fibers from non-fiber components, e.g., shives and epidermis/cuticle (Akin et al., 2001). Retting with a combination of Viscozyme L and Mayoquest 200 (containing about 38% EDTA), two commercial products, produced fibers with reasonable properties (Akin et al., 2001; Akin et al., 2002). Therefore, formulations with these compounds have constituted, more or less, our “standard” for evaluating other variables in developing an enzyme-retting system. Our work on various enzyme retting formulations has recently been reviewed (Akin et al., 2003). Clearly, retting and subsequent mechanical cleaning must be integrated for an effective commercial system, and data in this paper further
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confirm this interaction. Previous work has been reported in which a series of flax stems retted with different enzyme formulations was cleaned on a commercial ‘Unified Line’ system and further refined with the LaRoche system (Akin et al., 2001). In that study, 25 and 50 mM levels of EDTA were tested. Test yarns made with various blends of cotton and flax identified potential formulations for further study and indicated that enzyme plus 25 mM EDTA provided equally good fiber and yarn to that retted with enzyme plus 50 mM EDTA. The need to optimize enzyme-retting based on fiber properties (i.e., primarily strength and fineness) and formulation costs prompted the current research on a more expanded range of chelator and enzyme levels. Laboratory data involving hand-carding and Shirley cleaning of subsamples of the retted flax used herein confirmed that enzyme formulation influenced fiber properties and the relative chemical costs, based on experimental fiber yields from these methods (Akin et al., 2002). In that study, Mayoquest 200 with EDTA, which was used at substantially lower EDTA levels than previously tested, worked effectively with Viscozyme in enzyme-retting. EDTA level determined fiber fineness, while enzyme level determined fiber strength. Commercial systems require large amounts of material for testing, limiting the number of formulations that can be realistically evaluated. Therefore, a pilot plant version of the ‘Unified Line’ was designed in modules and with variable speed drive motors for maximum flexibility in testing smaller samples of enzyme-retted flax. Initial testing of flax through the Flax-PP indicated that the amount of shive removed varied for particular cleaning modules and particular samples (Akin et al., 2004). While retting influenced yield and properties, the Flax-PP was effective in producing fiber from all samples tested. The present research expands earlier studies (Akin et al., 2001, 2002) and integrates enzyme-retting, with an expanded range of formulations, with the Flax-PP to produce total fiber from flax. Furthermore, herein we tested a broader range of fiber products resulting from diverse processing steps. Data confirmed other reports (Akin et al., 2002) that the higher enzyme levels reduced fiber strength. Early work in Europe also indicated that strength of enzyme-retted fibers can be problematic, and extensive rinsing or oxidative treatment was required to denature enzymes to prevent further degradative action (Sharma and Van Sumere, 1992). Fibernodes in fibers and fiber bundles (Khalili et al., 2002) are particularly susceptible to cellulase, and larger amounts of enzymes or extended incubation times cause breaks at these regions (Akin et al., 2003; Evans et al., 2002). Possible solutions are to ret with pure
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endopolygalacturonases or cellulase-less mixtures, which adds costs, or reduce enzyme level or time of incubation (Akin et al., 2003). In this latter case, more aggressive cleaning could counteract less effective retting to some degree and produce adequate fibers. Data indicate clearly that there is an interaction between retting formulations and mechanical cleaning, and research on these issues can define conditions for fibers with specific properties. The many uses for flax fibers (Van Dam et al., 1994) require fibers of different properties and at different costs. Total fiber from flax stems, as produced herein, provides various types of fibers with a range of characteristics. The fine fiber yield, as estimated by Shirley-cleaning, represents one fraction of products that likely would have the highest value as textile grade. The low yields of fine fiber reported herein from one pass through a Shirley Analyzer, while not representative of those from commercial, refining systems, provides a means to evaluate formulations within the confines of this study. Fine fibers could be blended with cotton and other fibers and spun on short staple systems, as the by-product tow from long line production is now used. While uniform strength and fineness are required for textiles, different fabric designs, e.g., use of flax only in weft yarns, can take advantage of flax fibers with different properties. The use of enzyme formulations to ret flax provides a lighter color than dew-retted fibers and is closer to that produced by water-retting (Van Sumere, 1992). Knowledge and control of the ranges of color in fiber is advantageous in expanding the market for flax in textile blends (Epps and Akin, 2003). Results presented herein indicated the effect of chelator levels on redness. Use of flax in composites, e.g., automotive parts (Lepsch and Horal, 1998), may provide the greatest potential for expanded use of flax fibers in the future. Enzyme-retting could provide a method to ret linseed straw (Akin et al., 2001), which is currently produced in cold regions not conducive to fungal colonization and activity required for dew-retting. The cost and overall economy of enzyme-retting linseed straw would be influenced by many factors, including supply and demand, amount of high quality fibers for value-added applications, and other by-products of the process. These factors require evaluation. Flax fibers for the automotive industry are gaining widespread interest due to improved structural properties, processing benefits, and design flexibility and ease (CAFF, 2000). For example, use of flax in automobile parts results in weight reduction, improved sound absorbency, deep draw potential, and better impact shatter characteristics. Compared to glass, flax fibers are lower in cost, lower in density, biodegradable, and similar in
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elongation at break; tensile strength is lower for flax. Some report (Hagstram and Oksman, 2001) that flax fibers become more competitive with glass fiber for strength, when density and cost are considered. Substantial savings in energy costs are possible with natural fiber mats, which reportedly require about 80% less energy to manufacture than glass fiber (http://www.daimlerchrysler.com). In the present work, total fiber from the Flax-PP as well as Shirley by-product fiber provided coarser fibers that could be used for some composites. Preliminary tests have shown advantages of several of the enzyme-retted Shirley byproduct fibers over dew-retted samples for composites with recycled polyethylene (Foulk et al., 2004). For this sample of mature Ariane flax, retting with 0.05% Viscozyme plus 18 mM EDTA produced the highest yield of Flax-PP cleaned and Shirley-cleaned fibers, strong fine fibers of light color, and the strongest coarse fibers from Shirley by-product. In the companion laboratory study (Akin et al., 2002) using subsamples of this material, this formulation was shown to be of relatively low cost compared with formulations with higher enzyme levels (cost ratio of 1.73 compared to 1.00 for the lowest levels of enzymes and chelators). Flax fibers from other sources have recently been enzyme-retted with 0.1% Viscozyme + 18 mM EDTA (unpublished data). This sample of Jordan fiber flax resulted in an exceptionally clean, strong fiber after processing through the Flax-PP. Preliminary work of enzyme-retted and Flax-PP cleaned Jordan flax fiber indicated a much stronger nonwoven, needle-punched mat compared with the mature Ariane (unpublished data). This work expanded the research objectives, thus allowing for a variety of fibers to be tested in woven and non-woven applications. Use of diverse flax types, especially linseed straw, is a focus of our research for these applications, with optimization and integration of retting and cleaning to produce tailored fibers for industrial use at particular costs. REFERENCES Adamsen, A.P.S., Akin, D.E., and Rigsby, L.L., Chelating agents and enzyme retting of flax. Textile Res. J. 72, 296-302 (2002a). Adamsen, A.P.S., Akin, D.E., and Rigsby, L.L., Chemical retting of flax straw under alkaline conditions. Textile Res. J. 72, 789-794 (2002b). Akin, D. E., Dodd, R. B., Perkins, W., Henriksson, G., and Eriksson K.-E. L., Spray enzymatic retting: A new method for processing flax fibers. Textile Res. J. 70, 486-494 (2000a).
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Akin, D.E., Epps, H.H., Archibald, D.D., and Sharma, H.S.S., Color measurement of flax retted by various means. Textile Res. J. 70, 852-858 (2000b). Akin, D.E., Foulk, J.A., Dodd, R.B., and McAlister, D.D. III, Enzyme-retting of flax and characterization of processed fibers. J. Biotechnol. 89, 193-203 (2001). Akin, D.E., Foulk, J.A., and Dodd, R.B., Influence on flax fibers of components in enzyme retting formulations. Textile Res. J. 72, 510-514 (2002). Akin, D.E., Flax fiber. Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, Inc. DOI: 10.1002/0471238961.0612012401110914.a01. (2003). Akin, D.E., Henriksson, G., Evans, J.D., Adamsen, A.P.S., Foulk, J.A., and Dodd, R.B., Progress in enzyme-retting of flax. J. Natural Fibres. 1(1), 27-48. Annis, P.A., Campbell, J.H., and Brewer, M.S., Comparison of cottonized open end rotor spun flax/cotton blended fabrics. In “Fiber Flax Processing for Applications in Textiles and Composites,” Proceedings of the 2nd Center for American Fiber Flax Workshop, Clemson University, Clemson, SC, 2000, appendix V. ASTM D 1445-95, Standard test method for breaking strength and elongation of cotton fibers (flat bundle method), In “Annual Book of Standards,” Sec. 7 Textiles, ASTM, West Conshohocken, PA, 1999a, pp. 361-368. ASTM D 1448-97, Standard test method for micronaire reading of cotton fibers, In “Annual Book of Standards,” Sec. 7 Textiles, ASTM, West Conshohocken, PA, 1999b, p. 374-376. Berglund, D. R., Flax: new uses and demands, In “Trends in New Crops and New Uses,” J. Janick and A. Whipkey, Eds., ASHS Press, Alexandria, VA, 2002, pp. 358-360. Borland, V.S., From flower to fabric. Textile World, Oct. 2002, pp. 52-55. Borland, V.S., Fiber focus. Textile World, Aug. 2003, p. 45. Center for American Flax Fiber, “Fiber Flax Processing for Applications in Textiles and Composites,” Proceedings 2nd Workshop, Clemson University, Clemson, SC, 2000. Domier, K.W., An overview of the flax fibre industry in North America. Proc. 59th Flax Institute of the United States, North Dakota State University, Fargo, North Dakota, 2002, pp. 89-91. Epps, H.H., Akin, D.E., Foulk, J.A., and Dodd, R.B., Color of enzyme-retted flax fibers affected by processing, cleaning, and cottonizing. Textile Res. J. 71, 916-921 (2001). Epps, H.H., and Akin, D.E., The color gamut of undyed flax fiber. AATCC Rev. 3, 37-40 (2003). Evans, J.D., Akin D.E., and Foulk, J.A., Flax-retting by polygalacturonase-containing enzyme mixtures and effects on fiber properties. J. Biotechnol. 97, 223-231 (2002). Foulk, J.A., Akin, D.E., Dodd, R.B., and McAlister, D.D. III, Flax fiber: Potential for a new crop in the southeast, In “Trends in New Crops and New Uses,” J. Janick and A. Whipkey, Eds., ASHS Press, Alexandria, Virginia, 2002, pp. 361-370. Foulk, J.A., Chao, W.Y., Akin, D.E., Dodd, R.B., and Layton, P.A., Enzyme-retted flax fiber and recycled polyethylene composites. J. Polym. Environ. 12, 165-171 (2004). Gilbertson, H., “Proceedings of the 4th European Regional Workshop on Flax,” September 25-28, Rouen, France, Institut Technique du Lin, Paris, France, 1996, pp. 341-348.
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