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Textile Research Journal
Article
Enzyme Treatment of Wool and Specialty Hair Fibers Abstract
Enzyme treatment is one of the most prospective eco-friendly processes, for treating wool. Although, extensive research has been conducted on the effectiveness of enzymes as antifelting agents for wool, the use of enzymes as scouring agents for wool, versus conventional soap-scouring has not been studied. Furthermore, limited studies have been conducted on enzyme treatment of specialty hair fibers. This study evaluated the efficiency of enzymes (xylanase, pectinase, savinase, and resinase) in scouring wool, (merino and rambouillet) and specialty hair fibers (llama, alpaca, mohair and camel), in comparison with control treatments with hot water, and conventional soap. Various physical, chemical, and structural properties of the treated and untreated fibers were evaluated. Xylanase, and pectinase were found to clean the fibers as efficiently as soap, but without causing any physical damage to the fibers. Resinase was however, not an efficient scouring agent.
Trina Das and Gita N. Ramaswamy1 Department of Apparel, Textiles, and Interior Design Kansas State University, Manhattan, KS 66502, USA
Key words enzyme processing, wool, speciality hair fibers, scouring, protein fibers
The unique aesthetic quality of pure wool has made it irreplaceable even in a market dominated by its inexpensive and abundantly available synthetic versions such as acrylics. Wool constitutes a minor segment (1.98%) of the total textile fibers produced globally [1]. However, a significant portion of the wool is consumed by the high-end fashion market because of its warmth, resiliency, and handle. Within animal hair fibers, specialty hair fibers are considered to be even more exquisite than sheep wool [2]. Specialty hair fibers are fibers, obtained from animals other than sheep, such as, mohair, alpaca, llama and camel [3]. Mohair, obtained from the angora goat, is a long, white, and lustrous fiber, devoid of any crimp. Camel hair, shed by the two-humped Bactrian camel, is goldentan in color. Llama fibers, obtained from the ‘llamas’ of the Andes mountains, are fine and lustrous. Alpacas, which are also native to the Andes mountains, are domes-
Textile Research Journal Vol 76(2): 126–133 DOI: 10.1177/0040517506063387 Figures 1-4 appear in color online: http://trj.sagepub.com
ticated llamas and yield finer and stronger fibers than the llamas [3]. These fibers, mostly obtained from animals native to remote corners of 1the world, have a very small annual production, but capture the best markets in the high fashion industry [4]. Therefore, in spite of a small quantitative contribution, the significance of wool and specialty hair fibers in the apparel and textile industry cannot be under-rated. Animal hair fiber, especially sheep wool, has to pass through various stages of processing and cleaning (to get rid of the dirt, grease, vegetable matter, and other impurities in the raw state) before it can qualify as a marketable product [5]. Conventionally, some of these processes
1 Corresponding author: fax: +1785-532-3796; e-mail: [email protected]
www.trj.sagepub.com © 2006 SAGE Publications
Enzyme Treatment of Wool and Specialty Hair Fibers T. Das et al. require chlorination or application of chlorine-containing polymer, such as Hercosett [6, 7], which results in high levels of organic halogens discharged in waste-water [8]. This has been an issue of major environmental concern and has encouraged a lot of research in alternative eco-friendly processes such as enzyme treatment [6–8]. Enzymes are natural proteins which act as bio-catalysts [9]. Most of the enzymes used in textiles are hydrolases, which catalyze cleavage reactions through hydrolysis [6]. Examples are proteases, which break down proteins into amino acids and smaller peptides, lipases that break down lipids into fatty acids and glycerol, and cellulases that break down cellulose into glucose [9]. Enzymes used in wet-processing treatments of cotton, such as scouring, desizing, and stonewashing have already been introduced in the textile industry [10] and the possibilities of enzyme treatment for other fibers, especially wool, are under extensive research. Studies have been conducted on the effectiveness of proteolytic (6, 11, 12) and lipolytic [13] enzymes in improving wool properties such as shrink resistance, softness, and wettability. The review showed that extensive work has been done to determine the efficiency of enzymes in finishing treatments of wool, such as anti-felting treatments [6, 14, 15]. However, the effectiveness of enzymes as scouring agents for wool fibers, in comparison with conventional soap scouring treatments has not been studied. Furthermore, most work on enzyme treatment of wool has been confined to studies of a single type of wool – mainly merino wool. Limited work has been done on the enzyme treatment of specialty hair fibers [16]. As the grease content of these fibers are much less than in sheep wool [17–20], enzyme scouring of these fibers, under mild treatment conditions, for cleaning and improving softness, would be a worthwhile treatment. The enzymes used in this research are savinase, resinase, xylanase and pectinase. Savinase is a proteolytic enzyme, used in laundry detergents to remove protein-based stains [21]. Resinase is a lipase enzyme used in the paper pulp industry [22]. Apart from these the effects of using a xylanase, which breaks down hemicellulose [23], and pectinase, which breaks down pectins, which are complex mixtures of polysaccharides [24], were also studied. Xylanase, and pectinase were chosen to observe the efficiency of these enzymes in breaking down the waxes and sugar, present in the wool grease. Therefore, the objective of this study was, to do a comparative study of two varieties of wool and four varieties of specialty hair fibers, scoured with the enzymes xylanase, pectinase, savinase and resinase, and compare the results to plain hot-water-treated, soap-scoured, and untreated wool – for control. The enzyme-treated and control samples were evaluated for mechanical, structural, chemical and biological properties. The grease content of the treated and untreated fiber samples was also evaluated to measure and compare the cleaning efficiencies of the various treatments.
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Experimental Treatments Two varieties of sheep wool (merino and rambouillet) and four varieties of specialty hair fibers (llama, alpaca, camel, and mohair) were used in this study. Three replications from each of the six fiber types were subjected to four different enzymes scouring treatments (with xylanase, pectinase, savinase, and resinase) and two control treatments (with hot water and soap). Thus there were eighteen samples for each of the six treatments, and each fiber sample consisted of 10 g of fiber selected at random from the respective bags of fibers obtained from different shearing stations. Enzymes pectinase (Bioprep 3000L), xylanase (Novozym 628) and savinase (Savinase 16L, TYPE EX) were obtained from Novo Nordisk Biochem North America Inc. and enzyme Resinase A 2X was obtained from Novozymes North America, Inc. All the treatments were conducted for 5 minutes at a temperature of 60°C. All four enzymes were used at a concentration of 0.2% o.w.f. and the soap-scouring treatment was done using 2 g/mL of AATCC soap. For each treatment, 10 g of fiber samples were used with 300 mL of water for the hot water treatment and 298 mL of water for the enzyme and soap-scouring treatment, to get a material to liquor ratio of 1 : 30. A pH of 9.32 for xylanase, pectinase, and soap scouring, 9.0 for savinase, and 7.0 for resinase treatment were used (according to optimum conditions for each enzyme, obtained from literature). After each scouring treatment, the fiber samples were rinsed thoroughly in cold water and air dried. The physical, chemical and structural property, and grease content of all the treated, and untreated samples of each fiber type, were then evaluated and compared.
Physical Analysis Moisture content, of the conditioned fibers, and fiber diameter were measured according to the standard procedures [25–27].
Chemical Analysis Amino acid analysis was performed on single replications for each treated and untreated fiber type, using the ‘Model 420 A Derivatizer’. The samples were hydrolyzed for 24 hours at 110°C in 6 N solution of HCl, under vacuum and then derivatized using phenylisothiocyanate (PITC). Finally, the derivatives were analyzed in the highpressure liquid chromatography (HPLC) unit. Standard areas used were from 20 µL of a 25 nmol/mL standard solution. Fourier transform infrared (FTIR) spectroscopy was performed on single replications for each treated and untreated fiber types, using the Perkin Elmer Spectrum
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Table 1 ANOVA test results showing the effects of treatment and fiber type on all the properties tested on processed wool fibers. Effect of treatment Properties tested Moisture content Tenacity Elongation Diameter Grease content
Effect of fibre type
F-value
p-value
F-value
p-value
114.25 619.85 12.06 3.04 3.20
< 0.0001 < 0.0001 < 0.0001 < 0.0097 < 0.0151
12.00 62.53 55.18 44.59 6.67
< 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0003
*Degree of freedom for treatment type = 6 and fiber type = 5
One FTIR spectrophotometer. A single bounce Universal Attenuated Total Reflectance (U-ATR) accessory was attached to the FTIR spectrophotometer. The U-ATR is a diamond/ZnSe composite crystal with a pressure arm that allows a close contact between the surface of the wool pads and the crystal. The spectrophotometer was also interfaced to a computer and the scanned spectra were analyzed on Perkin Elmer Spectrum® version 3.01 software.
Grease Content Cleaning efficiency of the enzyme and control treatments were measured by evaluating the grease content of single replications of treated as well as untreated fiber samples (2 g), according to the procedures described in ASTM D-584 [28].
Structural Analysis Surface structure of the fiber samples were studied using the Hitachi S-3500N scanning electron microscope under an accelerating voltage of 5 kV.
Results and Discussion According to the experimental design, there were two independent variables, the treatment type, and the fiber type. Within treatment type there were seven levels. These were the four enzyme treatments, two control treatments, and the untreated stage. The fiber type comprised of the six different fiber varieties. The dependent variables were the different properties (physical, chemical and grease content) measured. The simultaneous effect of the two independent variables on the different dependent variables, were evaluated using SAS General Linear Model (SAS Institute Inc., Cary, NC) for two factor analysis of variance (ANOVA). Tukey’s Studentized range test was conducted to separate the means of the different properties for each fiber types and treatment types, at an α level of 0.05.
Table 1 shows the analysis of variance results of the main effects of treatment and fiber type on the properties of the treated and untreated fiber samples. Subjective evaluation and comparisons were made for the scanning electron microscope images, and FTIR spectra of the different untreated and treated fiber types.
Physical Properties The interaction effect between treatment and fiber type on the moisture content of fibers was found to be statistically significant (F = 1.99, p = 0.0077). Furthermore, both the treatment (F = 114.25 and p < 0.0001) and the fiber type (F = 12.0 and p < 0.0001) had a significant effect on the moisture content of the fibers. Higher moisture content values (Figure 1) were observed for xylanase, pectinase, and scoured treatments (12.5%) in comparison with other treatments (9.5 to 10%). This might be attributed to the greater removal of surface lipid layer from the epicuticle of the wool fiber, by these treatments, making the wool more hydrophilic [29]. The moisture content of conditioned merino wool was found to be the least (10.24%) in comparison to other fibers (11.6 to 11%). The overall range of moisture content values between fiber types was, however, quite small. The effect of treatments on fiber tenacity also demarcated scoured, xylanase, and pectinase treated fibers as the treatments that have higher tenacity values (4.5 g/denier) than those obtained for untreated, water, savinase, and resinase treatments (Figure 2). Among fiber types, merino and rambouillet wool had the lowest tenacity values (2.48 g/denier) as compared to the specialty hair fibers. The percentage elongation values of the sheep wool, on the other hand was higher then the specialty hair fibers. Mohair had the highest tenacity of all the fiber types studied (3.67 g/denier) and in terms of elongation it had higher values than the other specialty hair fibers. The effect of treatments on the elongation values of fibers (unlike in the case of tenacity) was less significant in comparison with the effect of fiber types. From the results of mean fiber diameter it was observed that the treatment did not have any noticeable effect on
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Figure 1 Moisture content (%) of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
Figure 2 Tenacity at break in g/den of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
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Figure 3 The mole % of cystein in all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments.
the fiber diameters. The effect of fiber types on diameter values was found to be quite significant. The sheep wool had the lowest fiber diameters (average of 25 µm), whereas alpaca and mohair had the highest diameters (36.1 and 31.8 µm, respectively) among all the fiber types. Diameter values of all the fiber types studied were close to the standard values, except for alpaca which had a much higher value than the standard, which is 27 µm. This was due to the large proportion of coarse guard hairs present in the alpaca fiber samples.
Chemical Properties With the exception of glycine, none of the other amino acids seemed to vary noticeably more between the different fiber types, as compared with the variation between the different treatments within the same fiber type. The glycine content of the sheep wool was consistently greater than the specialty hair fibers across all treatments. This, however, is not expected to have any effect on the treatments of these fibers since glycine is a non-reactive amino acid. Among all the reactive amino acids, cystein is considered to be the most significant, since the disulfide linkages affect the efficacy of various treatments. Therefore, the
effect of treatment and fiber type on the cystein content was studied with greater emphasis (Figure 3). It was observed that, the cystein content was lowered in the case of merino wool (by savinase and resinase), mohair (by xylanase, pectinase and savinase), and alpaca (by savinase) in comparison with the untreated fiber. This drop in cystein values might be attributed to the cystein being used up in the formation of lanthionine [29] under the effect of alkalinity that was present in all these treatment conditions. However, the amino acid analysis did not show any levels of lanthionine. On the other hand, the increase in cystein content in the case of rambouillet wool (in savinase, xylanase, pectinase and scoured fibers) in comparison with the untreated fiber, might be due to the cystein residues set free in the course of the amino acid analysis. From the FTIR analysis of the fiber samples, it was observed from the shift in the C–H asymmetric and symmetric bands at 2920 cm–1 and 2850–2870cm–1, respectively, that the treatments might have caused rearrangements of the molecular chains resulting in a tighter packing in the case of camel fibers and looser packing in the case of mohair, alpaca, and llama fibers [30]. The lipid band at around 1734 cm–1 appeared strongest in merino wool, and progressively less prominent in rambouillet, alpaca, mohair, camel, and llama fibers. The lipid band became
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Figure 4 The grease content percentage of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
less intense in the case of xylanase, pectinase, and resinase treated merino wool, in xylanase-treated rambouillet wool, and in all mohair fibers except the savinase-treated fibers.
Cleaning Efficiency From the results of grease content analysis of the treated as well as untreated fibers, it was observed that xylanase, pectinase and scoured fibers had much less grease content (average 1%) than the other treatment types (Figure 4). Untreated fibers had the highest grease content (11.2%), followed by resinase, water, and savinase treatments (average 6.3%). This is consistent with the results of moisture content, fiber tenacity and lipid band intensity studied in FTIR analysis. Resinase and savinase did not remove grease any better than hot water treatment alone. This implies that at the concentration used, neither resinase nor savinase were effective scouring agents. Among fiber types the sheep wool had significantly higher grease content than the specialty hair fibers.
Fiber Structure The scanning electron micrographs of all the treated and untreated fiber types reveal that none of the treat-
ments affected the fiber structures, physically beyond the cuticle. Xylanase, pectinase, savinase, and soap scouring produced a clean fiber surface, however with slight peeling in the case of xylanase and pectinase. Resinase, as well as hot water treatment, could not effectively clean the surface of any of the fibers, which accounts for the high grease content values of resinase and water-treated fibers.
Conclusion In this study, the effect of enzyme treatment (savinase, resinase, xylanase and pectinase) on the physical, chemical and structural properties of wool and specialty hair fibers were evaluated. It was observed that xylanase and pectinase treatments had as good a cleaning efficiency as conventional soap scouring. Furthermore, at the concentrations used, neither of these two enzymes caused any physical damage to the fibers, as confirmed by the tenacity and diameter values, and SEM pictures. The effectiveness of resinase as a scouring agent was, however, not very satisfactory. The results of this study have a lot of implication for the processing of wool and specialty hair fibers in the industry. Enzymes xylanase and pectinase would be very effective as
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scouring agents, especially for fibers such as llama, alpaca, camel, and mohair. Since specialty hair fibers possess very little impurities compared with sheep wool, the mild treatment conditions used in this study would be very appropriate for the treatment of these fibers. Moreover, at the extremely low concentrations used in this study, the use of enzymes is expected to result only in a limited increase in the cost of treatments. In future studies it would be interesting to observe the softness and shrinkage properties of fabric woven from enzyme-scoured wool/specialty hair fibers. Such studies might help realize the objective of attaining a non-felting, clean, and soft woolen product by subjecting the raw fiber to a single and mild enzyme scouring treatment at the fiber stage.
Acknowledgement We acknowledge helpful suggestions from Dr.Barbara Gatewood, and Dr.Sherry Haar. We are grateful to Jennifer Rogers and Renee for their assistance, and Kent Hampton, for providing technical assistance with SEM. We would also like to thank the Kansas State Agricultural Experiment Station for funding the project, and the Department of Entomology, and the Department of Biochemistry for letting us use their facilities. This research was also a part of the Southern Regional Research Project S-1002. This is contribution 04-105-J from the Kansas Agricultural Experiment Station.
9.
10. 11.
12.
13.
14.
15.
16.
17. 18. 19. 20.
21. 22.
Literature Cited 23. 1.
2.
3. 4. 5. 6.
7. 8.
Davies, B., The DRA All Fiber Model: A Unique Tool to help Chemical Companies’ Long Term Planning. CMAI Global Fibers and Feedstock Report, Issue No. 001, 2001. Retrieved February 4, 2004, from http://www.davidrigbyassociates.c0m/ DRA%20WEBSITE%2003/assets/Sept.pdf Canadian Fashion and Design, Specialty Fibers. Retrieved September 9, 2002, from http://www.ntgi.net/ICCF&D/index2. html Hatch, K. L., “Textile Science,” West Publishing Company, Minneapolis, (1993), pp. 141–153. Veltjens 1996. Retrieved December 22 2005, from http://www. surifarm.de/Lings.lings.htm Moncrieff, R. W., “Wool Shrinkage and Its Prevention,” National Trade Press, London, 1953. Jovancic, P., Jocic, D., and Dumic, J., The Efficiency of an Enzyme Treatment in Reducing Wool Shrinkage. J. Textile Inst. 89(2), 390–399 (1998). Pascual, E., and Julia, M. R., The Role of Chitosan in Wool Finishing. J. Biotechnol., 89, 289–296 (2001). El-Sayed, H., Hamed, R. R., and Kantouch, A., EnzymeBased Feltproofing of Wool. AATCC Rev. January, 25–28 (2002).
24.
25.
26.
27.
28.
Enzyme Technical Association, Enzymes A Primer on Uses Today and Tomorrow, 2001. Retrieved September 9, 2002, from http://www.enzymetechnical.org Thiry, M. C. Enzymes in the Tool Box. AATCC Review, August, 14–19 (2001). Bishop, D. P., Shen, J., Heine, E., and Hollfelder, B., The Use of Proteolytic enzymes to Reduce Wool-fiber Stiffness and Prickle. J. Textile Inst. 89(3), 546–553 (1998). Chikkodi, S. V., Khan, S., and Mehta, R. D., Effects of Biofinishing on Cotton/Wool Blended Fabrics. Textile Res. J. 65(10), 564–569 (1995). Nolte, H., and Bishop, D. P., Effects of Proteolytic and Lipolytic Enzymes on Untreated and Shrink-resist-treated Wool. J. Textile Inst. 87(1), 212–226 (1996). Shen, J., Bishop, D. P., Heine, E., and Hollfelder, B., Some Factors Affecting the Control of Proteolytic Enzyme Reactions on Wool. J. Textile Inst. 90(3), 404–411 (1999). Schumacher, K., Heine, E., and Höcker, H., Extremozymes for Improving Wool Properties. J. Biotechnol. 89, 281–289 (2001). Hughes, V. L., Nelson, G., and East, G., Surface Modification of Cashmere Fibers by Reverse Proteolysis. AATCC Review, March, 39–43 (2001). Canchones Alpaca Stud, FAQ. Retrieved September 9, 2002, from http://www.canchones.com.au/Faq/faq.htm Llama Org, Llama Fiber, 2000. Retrieved September 9, 2002, from http://www.llama.org/llama-fiber.htm DaDalt, S. E. The New Hampshire Llama Association Newsletter, 7(5), 4–7, September 1997. Melodie Hill, Llama Wool and Mohair. Retrieved September 9, 2002, from http://www.members.aol.com/cnorwoo627/wool. html Reaction Intrade, Products Retrieved September 9, 2002, from http://www.reaction.co.20/Products/products.htm Martinez, A. T., New Environmentally Sound Methods for Pitch Control in Different Paper Pulp Manufacturing Processes, 2001. Retrieved September 9, 2002, from http://www. paperloop.com/pp-mag/paperhelp/11-3.shtml Kirkman Laboratories, Enzym-Complete with DPP-IV, 2002. Retrieved September 9, 2002, from http://www.kirkmanlabs. com/products/enzymes/enzym_dppiv/Enzym_Complete_w_ DPP_IV_C_60_234.html The European Association for Bioindustries, Europabio’s Biotechnology Information Kit, 2002. Retrieved September 9, 2002, from http://www.europabio.org/pages/module14.asp. ASTM D 1576, “Standard Test Method for in Wool by OvenDrying, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp. 434–437, 1995. ASTM D 3822, “Standard Test method for Tensile Properties of Single Textile Fibers, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.02, pp. 144–153, 1996. ASTM D 2130, “Standard Test Method for Diameter of Wool and other Animal Fibers by Microprojection, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp. 571–579, 1995. ASTM D-584, “Test Method for Wool Content of Raw Wool, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp., 1995.
Enzyme Treatment of Wool and Specialty Hair Fibers T. Das et al. 29. Jones L. N., Rivett, D. E., and Tucker, D. J., Wool and Related Mammalian Fibers in “Handbook of Fiber Chemistry,” M. Lewin, and E. M. Pearce, Eds., Marcel Dekker, Inc., New York, pp. 355–413, 1998.
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30. Fonollosa, J., Marti, M., Maza, A. D. L., Sabes, M., Parra, J. L., and Coderch, L., Thermodynamic and Structural Aspects of Internal Wool Lipids, 1999. Retrieved May 1 1999 from http://www.csgi.unifi.it/art10/biblio/articoli/lana.pdf
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Article
Enzyme Treatment of Wool and Specialty Hair Fibers Abstract
Enzyme treatment is one of the most prospective eco-friendly processes, for treating wool. Although, extensive research has been conducted on the effectiveness of enzymes as antifelting agents for wool, the use of enzymes as scouring agents for wool, versus conventional soap-scouring has not been studied. Furthermore, limited studies have been conducted on enzyme treatment of specialty hair fibers. This study evaluated the efficiency of enzymes (xylanase, pectinase, savinase, and resinase) in scouring wool, (merino and rambouillet) and specialty hair fibers (llama, alpaca, mohair and camel), in comparison with control treatments with hot water, and conventional soap. Various physical, chemical, and structural properties of the treated and untreated fibers were evaluated. Xylanase, and pectinase were found to clean the fibers as efficiently as soap, but without causing any physical damage to the fibers. Resinase was however, not an efficient scouring agent.
Trina Das and Gita N. Ramaswamy1 Department of Apparel, Textiles, and Interior Design Kansas State University, Manhattan, KS 66502, USA
Key words enzyme processing, wool, speciality hair fibers, scouring, protein fibers
The unique aesthetic quality of pure wool has made it irreplaceable even in a market dominated by its inexpensive and abundantly available synthetic versions such as acrylics. Wool constitutes a minor segment (1.98%) of the total textile fibers produced globally [1]. However, a significant portion of the wool is consumed by the high-end fashion market because of its warmth, resiliency, and handle. Within animal hair fibers, specialty hair fibers are considered to be even more exquisite than sheep wool [2]. Specialty hair fibers are fibers, obtained from animals other than sheep, such as, mohair, alpaca, llama and camel [3]. Mohair, obtained from the angora goat, is a long, white, and lustrous fiber, devoid of any crimp. Camel hair, shed by the two-humped Bactrian camel, is goldentan in color. Llama fibers, obtained from the ‘llamas’ of the Andes mountains, are fine and lustrous. Alpacas, which are also native to the Andes mountains, are domes-
Textile Research Journal Vol 76(2): 126–133 DOI: 10.1177/0040517506063387 Figures 1-4 appear in color online: http://trj.sagepub.com
ticated llamas and yield finer and stronger fibers than the llamas [3]. These fibers, mostly obtained from animals native to remote corners of 1the world, have a very small annual production, but capture the best markets in the high fashion industry [4]. Therefore, in spite of a small quantitative contribution, the significance of wool and specialty hair fibers in the apparel and textile industry cannot be under-rated. Animal hair fiber, especially sheep wool, has to pass through various stages of processing and cleaning (to get rid of the dirt, grease, vegetable matter, and other impurities in the raw state) before it can qualify as a marketable product [5]. Conventionally, some of these processes
1 Corresponding author: fax: +1785-532-3796; e-mail: [email protected]
www.trj.sagepub.com © 2006 SAGE Publications
Enzyme Treatment of Wool and Specialty Hair Fibers T. Das et al. require chlorination or application of chlorine-containing polymer, such as Hercosett [6, 7], which results in high levels of organic halogens discharged in waste-water [8]. This has been an issue of major environmental concern and has encouraged a lot of research in alternative eco-friendly processes such as enzyme treatment [6–8]. Enzymes are natural proteins which act as bio-catalysts [9]. Most of the enzymes used in textiles are hydrolases, which catalyze cleavage reactions through hydrolysis [6]. Examples are proteases, which break down proteins into amino acids and smaller peptides, lipases that break down lipids into fatty acids and glycerol, and cellulases that break down cellulose into glucose [9]. Enzymes used in wet-processing treatments of cotton, such as scouring, desizing, and stonewashing have already been introduced in the textile industry [10] and the possibilities of enzyme treatment for other fibers, especially wool, are under extensive research. Studies have been conducted on the effectiveness of proteolytic (6, 11, 12) and lipolytic [13] enzymes in improving wool properties such as shrink resistance, softness, and wettability. The review showed that extensive work has been done to determine the efficiency of enzymes in finishing treatments of wool, such as anti-felting treatments [6, 14, 15]. However, the effectiveness of enzymes as scouring agents for wool fibers, in comparison with conventional soap scouring treatments has not been studied. Furthermore, most work on enzyme treatment of wool has been confined to studies of a single type of wool – mainly merino wool. Limited work has been done on the enzyme treatment of specialty hair fibers [16]. As the grease content of these fibers are much less than in sheep wool [17–20], enzyme scouring of these fibers, under mild treatment conditions, for cleaning and improving softness, would be a worthwhile treatment. The enzymes used in this research are savinase, resinase, xylanase and pectinase. Savinase is a proteolytic enzyme, used in laundry detergents to remove protein-based stains [21]. Resinase is a lipase enzyme used in the paper pulp industry [22]. Apart from these the effects of using a xylanase, which breaks down hemicellulose [23], and pectinase, which breaks down pectins, which are complex mixtures of polysaccharides [24], were also studied. Xylanase, and pectinase were chosen to observe the efficiency of these enzymes in breaking down the waxes and sugar, present in the wool grease. Therefore, the objective of this study was, to do a comparative study of two varieties of wool and four varieties of specialty hair fibers, scoured with the enzymes xylanase, pectinase, savinase and resinase, and compare the results to plain hot-water-treated, soap-scoured, and untreated wool – for control. The enzyme-treated and control samples were evaluated for mechanical, structural, chemical and biological properties. The grease content of the treated and untreated fiber samples was also evaluated to measure and compare the cleaning efficiencies of the various treatments.
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Experimental Treatments Two varieties of sheep wool (merino and rambouillet) and four varieties of specialty hair fibers (llama, alpaca, camel, and mohair) were used in this study. Three replications from each of the six fiber types were subjected to four different enzymes scouring treatments (with xylanase, pectinase, savinase, and resinase) and two control treatments (with hot water and soap). Thus there were eighteen samples for each of the six treatments, and each fiber sample consisted of 10 g of fiber selected at random from the respective bags of fibers obtained from different shearing stations. Enzymes pectinase (Bioprep 3000L), xylanase (Novozym 628) and savinase (Savinase 16L, TYPE EX) were obtained from Novo Nordisk Biochem North America Inc. and enzyme Resinase A 2X was obtained from Novozymes North America, Inc. All the treatments were conducted for 5 minutes at a temperature of 60°C. All four enzymes were used at a concentration of 0.2% o.w.f. and the soap-scouring treatment was done using 2 g/mL of AATCC soap. For each treatment, 10 g of fiber samples were used with 300 mL of water for the hot water treatment and 298 mL of water for the enzyme and soap-scouring treatment, to get a material to liquor ratio of 1 : 30. A pH of 9.32 for xylanase, pectinase, and soap scouring, 9.0 for savinase, and 7.0 for resinase treatment were used (according to optimum conditions for each enzyme, obtained from literature). After each scouring treatment, the fiber samples were rinsed thoroughly in cold water and air dried. The physical, chemical and structural property, and grease content of all the treated, and untreated samples of each fiber type, were then evaluated and compared.
Physical Analysis Moisture content, of the conditioned fibers, and fiber diameter were measured according to the standard procedures [25–27].
Chemical Analysis Amino acid analysis was performed on single replications for each treated and untreated fiber type, using the ‘Model 420 A Derivatizer’. The samples were hydrolyzed for 24 hours at 110°C in 6 N solution of HCl, under vacuum and then derivatized using phenylisothiocyanate (PITC). Finally, the derivatives were analyzed in the highpressure liquid chromatography (HPLC) unit. Standard areas used were from 20 µL of a 25 nmol/mL standard solution. Fourier transform infrared (FTIR) spectroscopy was performed on single replications for each treated and untreated fiber types, using the Perkin Elmer Spectrum
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Table 1 ANOVA test results showing the effects of treatment and fiber type on all the properties tested on processed wool fibers. Effect of treatment Properties tested Moisture content Tenacity Elongation Diameter Grease content
Effect of fibre type
F-value
p-value
F-value
p-value
114.25 619.85 12.06 3.04 3.20
< 0.0001 < 0.0001 < 0.0001 < 0.0097 < 0.0151
12.00 62.53 55.18 44.59 6.67
< 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0003
*Degree of freedom for treatment type = 6 and fiber type = 5
One FTIR spectrophotometer. A single bounce Universal Attenuated Total Reflectance (U-ATR) accessory was attached to the FTIR spectrophotometer. The U-ATR is a diamond/ZnSe composite crystal with a pressure arm that allows a close contact between the surface of the wool pads and the crystal. The spectrophotometer was also interfaced to a computer and the scanned spectra were analyzed on Perkin Elmer Spectrum® version 3.01 software.
Grease Content Cleaning efficiency of the enzyme and control treatments were measured by evaluating the grease content of single replications of treated as well as untreated fiber samples (2 g), according to the procedures described in ASTM D-584 [28].
Structural Analysis Surface structure of the fiber samples were studied using the Hitachi S-3500N scanning electron microscope under an accelerating voltage of 5 kV.
Results and Discussion According to the experimental design, there were two independent variables, the treatment type, and the fiber type. Within treatment type there were seven levels. These were the four enzyme treatments, two control treatments, and the untreated stage. The fiber type comprised of the six different fiber varieties. The dependent variables were the different properties (physical, chemical and grease content) measured. The simultaneous effect of the two independent variables on the different dependent variables, were evaluated using SAS General Linear Model (SAS Institute Inc., Cary, NC) for two factor analysis of variance (ANOVA). Tukey’s Studentized range test was conducted to separate the means of the different properties for each fiber types and treatment types, at an α level of 0.05.
Table 1 shows the analysis of variance results of the main effects of treatment and fiber type on the properties of the treated and untreated fiber samples. Subjective evaluation and comparisons were made for the scanning electron microscope images, and FTIR spectra of the different untreated and treated fiber types.
Physical Properties The interaction effect between treatment and fiber type on the moisture content of fibers was found to be statistically significant (F = 1.99, p = 0.0077). Furthermore, both the treatment (F = 114.25 and p < 0.0001) and the fiber type (F = 12.0 and p < 0.0001) had a significant effect on the moisture content of the fibers. Higher moisture content values (Figure 1) were observed for xylanase, pectinase, and scoured treatments (12.5%) in comparison with other treatments (9.5 to 10%). This might be attributed to the greater removal of surface lipid layer from the epicuticle of the wool fiber, by these treatments, making the wool more hydrophilic [29]. The moisture content of conditioned merino wool was found to be the least (10.24%) in comparison to other fibers (11.6 to 11%). The overall range of moisture content values between fiber types was, however, quite small. The effect of treatments on fiber tenacity also demarcated scoured, xylanase, and pectinase treated fibers as the treatments that have higher tenacity values (4.5 g/denier) than those obtained for untreated, water, savinase, and resinase treatments (Figure 2). Among fiber types, merino and rambouillet wool had the lowest tenacity values (2.48 g/denier) as compared to the specialty hair fibers. The percentage elongation values of the sheep wool, on the other hand was higher then the specialty hair fibers. Mohair had the highest tenacity of all the fiber types studied (3.67 g/denier) and in terms of elongation it had higher values than the other specialty hair fibers. The effect of treatments on the elongation values of fibers (unlike in the case of tenacity) was less significant in comparison with the effect of fiber types. From the results of mean fiber diameter it was observed that the treatment did not have any noticeable effect on
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Figure 1 Moisture content (%) of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
Figure 2 Tenacity at break in g/den of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
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Figure 3 The mole % of cystein in all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments.
the fiber diameters. The effect of fiber types on diameter values was found to be quite significant. The sheep wool had the lowest fiber diameters (average of 25 µm), whereas alpaca and mohair had the highest diameters (36.1 and 31.8 µm, respectively) among all the fiber types. Diameter values of all the fiber types studied were close to the standard values, except for alpaca which had a much higher value than the standard, which is 27 µm. This was due to the large proportion of coarse guard hairs present in the alpaca fiber samples.
Chemical Properties With the exception of glycine, none of the other amino acids seemed to vary noticeably more between the different fiber types, as compared with the variation between the different treatments within the same fiber type. The glycine content of the sheep wool was consistently greater than the specialty hair fibers across all treatments. This, however, is not expected to have any effect on the treatments of these fibers since glycine is a non-reactive amino acid. Among all the reactive amino acids, cystein is considered to be the most significant, since the disulfide linkages affect the efficacy of various treatments. Therefore, the
effect of treatment and fiber type on the cystein content was studied with greater emphasis (Figure 3). It was observed that, the cystein content was lowered in the case of merino wool (by savinase and resinase), mohair (by xylanase, pectinase and savinase), and alpaca (by savinase) in comparison with the untreated fiber. This drop in cystein values might be attributed to the cystein being used up in the formation of lanthionine [29] under the effect of alkalinity that was present in all these treatment conditions. However, the amino acid analysis did not show any levels of lanthionine. On the other hand, the increase in cystein content in the case of rambouillet wool (in savinase, xylanase, pectinase and scoured fibers) in comparison with the untreated fiber, might be due to the cystein residues set free in the course of the amino acid analysis. From the FTIR analysis of the fiber samples, it was observed from the shift in the C–H asymmetric and symmetric bands at 2920 cm–1 and 2850–2870cm–1, respectively, that the treatments might have caused rearrangements of the molecular chains resulting in a tighter packing in the case of camel fibers and looser packing in the case of mohair, alpaca, and llama fibers [30]. The lipid band at around 1734 cm–1 appeared strongest in merino wool, and progressively less prominent in rambouillet, alpaca, mohair, camel, and llama fibers. The lipid band became
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Figure 4 The grease content percentage of all wool/specialty hair fiber types (merino, rambouillet, llama, camel, alpaca, and mohair) subjected to various treatments (untreated, scoured, water treated, xylanase, pectinase, savinase and resinase enzyme treatments).
less intense in the case of xylanase, pectinase, and resinase treated merino wool, in xylanase-treated rambouillet wool, and in all mohair fibers except the savinase-treated fibers.
Cleaning Efficiency From the results of grease content analysis of the treated as well as untreated fibers, it was observed that xylanase, pectinase and scoured fibers had much less grease content (average 1%) than the other treatment types (Figure 4). Untreated fibers had the highest grease content (11.2%), followed by resinase, water, and savinase treatments (average 6.3%). This is consistent with the results of moisture content, fiber tenacity and lipid band intensity studied in FTIR analysis. Resinase and savinase did not remove grease any better than hot water treatment alone. This implies that at the concentration used, neither resinase nor savinase were effective scouring agents. Among fiber types the sheep wool had significantly higher grease content than the specialty hair fibers.
Fiber Structure The scanning electron micrographs of all the treated and untreated fiber types reveal that none of the treat-
ments affected the fiber structures, physically beyond the cuticle. Xylanase, pectinase, savinase, and soap scouring produced a clean fiber surface, however with slight peeling in the case of xylanase and pectinase. Resinase, as well as hot water treatment, could not effectively clean the surface of any of the fibers, which accounts for the high grease content values of resinase and water-treated fibers.
Conclusion In this study, the effect of enzyme treatment (savinase, resinase, xylanase and pectinase) on the physical, chemical and structural properties of wool and specialty hair fibers were evaluated. It was observed that xylanase and pectinase treatments had as good a cleaning efficiency as conventional soap scouring. Furthermore, at the concentrations used, neither of these two enzymes caused any physical damage to the fibers, as confirmed by the tenacity and diameter values, and SEM pictures. The effectiveness of resinase as a scouring agent was, however, not very satisfactory. The results of this study have a lot of implication for the processing of wool and specialty hair fibers in the industry. Enzymes xylanase and pectinase would be very effective as
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scouring agents, especially for fibers such as llama, alpaca, camel, and mohair. Since specialty hair fibers possess very little impurities compared with sheep wool, the mild treatment conditions used in this study would be very appropriate for the treatment of these fibers. Moreover, at the extremely low concentrations used in this study, the use of enzymes is expected to result only in a limited increase in the cost of treatments. In future studies it would be interesting to observe the softness and shrinkage properties of fabric woven from enzyme-scoured wool/specialty hair fibers. Such studies might help realize the objective of attaining a non-felting, clean, and soft woolen product by subjecting the raw fiber to a single and mild enzyme scouring treatment at the fiber stage.
Acknowledgement We acknowledge helpful suggestions from Dr.Barbara Gatewood, and Dr.Sherry Haar. We are grateful to Jennifer Rogers and Renee for their assistance, and Kent Hampton, for providing technical assistance with SEM. We would also like to thank the Kansas State Agricultural Experiment Station for funding the project, and the Department of Entomology, and the Department of Biochemistry for letting us use their facilities. This research was also a part of the Southern Regional Research Project S-1002. This is contribution 04-105-J from the Kansas Agricultural Experiment Station.
9.
10. 11.
12.
13.
14.
15.
16.
17. 18. 19. 20.
21. 22.
Literature Cited 23. 1.
2.
3. 4. 5. 6.
7. 8.
Davies, B., The DRA All Fiber Model: A Unique Tool to help Chemical Companies’ Long Term Planning. CMAI Global Fibers and Feedstock Report, Issue No. 001, 2001. Retrieved February 4, 2004, from http://www.davidrigbyassociates.c0m/ DRA%20WEBSITE%2003/assets/Sept.pdf Canadian Fashion and Design, Specialty Fibers. Retrieved September 9, 2002, from http://www.ntgi.net/ICCF&D/index2. html Hatch, K. L., “Textile Science,” West Publishing Company, Minneapolis, (1993), pp. 141–153. Veltjens 1996. Retrieved December 22 2005, from http://www. surifarm.de/Lings.lings.htm Moncrieff, R. W., “Wool Shrinkage and Its Prevention,” National Trade Press, London, 1953. Jovancic, P., Jocic, D., and Dumic, J., The Efficiency of an Enzyme Treatment in Reducing Wool Shrinkage. J. Textile Inst. 89(2), 390–399 (1998). Pascual, E., and Julia, M. R., The Role of Chitosan in Wool Finishing. J. Biotechnol., 89, 289–296 (2001). El-Sayed, H., Hamed, R. R., and Kantouch, A., EnzymeBased Feltproofing of Wool. AATCC Rev. January, 25–28 (2002).
24.
25.
26.
27.
28.
Enzyme Technical Association, Enzymes A Primer on Uses Today and Tomorrow, 2001. Retrieved September 9, 2002, from http://www.enzymetechnical.org Thiry, M. C. Enzymes in the Tool Box. AATCC Review, August, 14–19 (2001). Bishop, D. P., Shen, J., Heine, E., and Hollfelder, B., The Use of Proteolytic enzymes to Reduce Wool-fiber Stiffness and Prickle. J. Textile Inst. 89(3), 546–553 (1998). Chikkodi, S. V., Khan, S., and Mehta, R. D., Effects of Biofinishing on Cotton/Wool Blended Fabrics. Textile Res. J. 65(10), 564–569 (1995). Nolte, H., and Bishop, D. P., Effects of Proteolytic and Lipolytic Enzymes on Untreated and Shrink-resist-treated Wool. J. Textile Inst. 87(1), 212–226 (1996). Shen, J., Bishop, D. P., Heine, E., and Hollfelder, B., Some Factors Affecting the Control of Proteolytic Enzyme Reactions on Wool. J. Textile Inst. 90(3), 404–411 (1999). Schumacher, K., Heine, E., and Höcker, H., Extremozymes for Improving Wool Properties. J. Biotechnol. 89, 281–289 (2001). Hughes, V. L., Nelson, G., and East, G., Surface Modification of Cashmere Fibers by Reverse Proteolysis. AATCC Review, March, 39–43 (2001). Canchones Alpaca Stud, FAQ. Retrieved September 9, 2002, from http://www.canchones.com.au/Faq/faq.htm Llama Org, Llama Fiber, 2000. Retrieved September 9, 2002, from http://www.llama.org/llama-fiber.htm DaDalt, S. E. The New Hampshire Llama Association Newsletter, 7(5), 4–7, September 1997. Melodie Hill, Llama Wool and Mohair. Retrieved September 9, 2002, from http://www.members.aol.com/cnorwoo627/wool. html Reaction Intrade, Products Retrieved September 9, 2002, from http://www.reaction.co.20/Products/products.htm Martinez, A. T., New Environmentally Sound Methods for Pitch Control in Different Paper Pulp Manufacturing Processes, 2001. Retrieved September 9, 2002, from http://www. paperloop.com/pp-mag/paperhelp/11-3.shtml Kirkman Laboratories, Enzym-Complete with DPP-IV, 2002. Retrieved September 9, 2002, from http://www.kirkmanlabs. com/products/enzymes/enzym_dppiv/Enzym_Complete_w_ DPP_IV_C_60_234.html The European Association for Bioindustries, Europabio’s Biotechnology Information Kit, 2002. Retrieved September 9, 2002, from http://www.europabio.org/pages/module14.asp. ASTM D 1576, “Standard Test Method for in Wool by OvenDrying, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp. 434–437, 1995. ASTM D 3822, “Standard Test method for Tensile Properties of Single Textile Fibers, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.02, pp. 144–153, 1996. ASTM D 2130, “Standard Test Method for Diameter of Wool and other Animal Fibers by Microprojection, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp. 571–579, 1995. ASTM D-584, “Test Method for Wool Content of Raw Wool, Annual Book of ASTM Standards,” American Society for Testing and Materials, Philadelphia, PA, Vol. 07.01, pp., 1995.
Enzyme Treatment of Wool and Specialty Hair Fibers T. Das et al. 29. Jones L. N., Rivett, D. E., and Tucker, D. J., Wool and Related Mammalian Fibers in “Handbook of Fiber Chemistry,” M. Lewin, and E. M. Pearce, Eds., Marcel Dekker, Inc., New York, pp. 355–413, 1998.
133
30. Fonollosa, J., Marti, M., Maza, A. D. L., Sabes, M., Parra, J. L., and Coderch, L., Thermodynamic and Structural Aspects of Internal Wool Lipids, 1999. Retrieved May 1 1999 from http://www.csgi.unifi.it/art10/biblio/articoli/lana.pdf
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