The Effects of Cellulase and Laccase Enzyme Treatments on Pineapple Fibers Ece Kalayci, Arzu Yavas and Ozan Avinc* Pamukkale University, Faculty of Engineering, Textile Engineering Department, 20160 Denizli, Turkey *Corresponding Author:
[email protected]
ABSTRACT Every year in the regions of tropical and sub-tropical climates, tons of pineapple plant leaves are left as agrowaste material since pineapple plant is mostly farmed for its fruit. In order to utilize the obtained waste, pineapple fibers are extracted from the pineapple leaves by conventional methods and used for traditional purposes such as various clothes and table linens production. Pineapple fibers can also be blended with various other fibers such as cotton, silk, polyester, banana etc. In this study, the effects of laccase enzyme, acid cellulase enzyme and neutral cellulase enzyme on the pineapple fibers were investigated. Enzymes are increasingly being used in the textile industry for sustainable and ecofriendly production. After different enzymatic treatments, whiteness, yellowness indexes and absorption capacities of pineapple fibers were evaluated. Cellulase and laccase enzymes resulted in an increase on the yellowness index and a decrease on the whiteness index of the pineapple fibers. Furthermore, absorption capacity of the pineapple fibers was enhanced by an increasing enzyme concentration. On the other hand, it was also observed that the high concentration usage of acid cellulase enzyme led to a significant damage on the fiber structure. Keywords: pineapple fiber, natural fiber, agrowaste fiber, cellulose enzyme, laccase enzyme
INTRODUCTION Pineapple fiber is a natural lingo-cellulosic fiber extracted from pineapple plant leaves. Pineapple plant is mostly cultivated in tropic and sub-tropic countries. Pineapple plant farming has an important role in tropic and sub-tropic countries’ agriculture and it is mostly cultivated for its fruit (1-3). Tons of pineapple plant leaves are left as agrowaste material since pineapple plant is mostly farmed for its fruit. Pineapple fibers can also be categorized as agrowaste fiber since the majority of pineapple fibers are extracted from waste pineapple plant leaves. Pineapple fiber is a popular and worthy textile material especially in Philippines. Even though it is a valuable textile material in that region, pineapple fiber has a limited usage in the global textile industry. Pineapple fiber has excellent properties such as high strength and modulus (1, 4). However, the properties and the composition of raw pineapple fibers are related to climate conditions, soil, age of plant and harvesting time (1, 5). Pineapple fiber is usually composed highly amount of cellulose (70-82% based on weight of fibers) and 16-22,2% hemicellulose, 5-13% lignin, 2,5-3,5% wax and others (1, 6). Pineapple fiber is generally used for traditional clothes and table linens. Lately, researchers have been focused on its availability and usability in natural composites. Pineapple fiber has a great potential to be used in global textile industry owing to it outstanding properties and structure. Also, it can be blended with various other fibers such as cotton, silk, polyester, banana, etc. Enzymes have been used for years in textile applications (7). Laccase enzyme are widely used for the decolorization of textile effluents and textile bleaching (8). It is reported in previous studies that laccase enzyme can enhance whiteness degrees of cotton fiber by oxidation of flavonoids (8). Cellulase enzyme is a multi-component enzymatic system and it catalyses the breakdown of cellulose to smaller oligosaccharides and finally glucose (9, 10). Cellulase enzyme applications became an important eco-friendly method for textile finishing processes such as denim finishing, pilling and fuzz
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fiber removal processes (8, 10). Cellulase enzymes can be categorized as acid stable (pH 4.5-.5.5), neutral (pH 6-7) or alkali stable (pH 9-10) in relation to their sensitivity to pH (8). This study aims to investigate the changes in the colorimetric properties (whiteness index, yellowness index and lightness degrees) and absorption capacity of the pineapple fabric after cellulase and laccase enzyme treatments. EXPERIMENTAL Material In this study, 100% natural pineapple fiber woven fabric was utilized. The weight of woven pineapple fabric was 32.06 g/m2. Commercially available laccase and cellulase enzymes (acid cellulase enzymes and neutral cellulase enzyme) were used during enzyme treatments. Enzymes were supplied from Rudolf Duraner and Alfa Kimya. Method Firstly, conventional alkaline treatment with sodium hydroxide was applied to pineapple fiber fabrics. Alkali treatment process was carried out with 1 ml/l nonionic surfactant and 2% (owf) NaOH at 90oC for 30 minutes with a liquor ratio of 1:40. Then fabrics were washed at 80oC for 2 minutes and at 40oC for 5 minutes. Afterwards, fabrics were subjected to cold washing. Enzyme application duration, temperature, and concentration were determined according to their recommended commercial applications by the producers. Laccase enzyme treatments (0.5%, 2% and 4%, owf) were carried out at 70oC between pH 4,5-5,5 for 20 minutes with 1 g/l non-ionic surfactant following application at 70oC and for 20 minutes in order to deactivate the laccase enzymes. Two different commercial available acid cellulase enzymes were used. These enzymes will be expressed as “Acid cellulase A” and “Acid cellulase B” in this study. “Acid cellulase A” enzyme treatments (0.5%, 2% and 4% owf) were carried out at 55oC and pH 8 for 30 minutes with 1 g/l non-ionic surfactant following application at 80oC and pH 9-10 for 20 minutes in order to deactivate the acid cellulase enzymes. “Acid cellulase B” treatments (0.5%, 2% and 4%, owf) were carried out at 50oC and pH 5 for 45 minutes with 1 g/l non-ionic wetting agent followed by posttreatment at 80oC (pH 10) for 10 minutes in order to again deactivate acid cellulase enzymes. Neutral cellulase enzyme treatments (0.5%, 2% and 4%, owf) were carried out at 50oC between pH 6-6.5 for 45 minutes with 1 g/l non-ionic surfactant following application at 80oC for 20 minutes in order to deactivate the neutral cellulase enzymes. All samples then washed successively at 80oC for 2 minutes and at 40oC for 5 minutes and finally with cold water. After enzyme treatments, color properties and absorption capacities of treated pineapple fabrics were evaluated. Absorption capacity was measured according to EDANA 10.3.99 Standard (11). Whiteness and yellowness indexes were measured using a DataColor 600 spectrophotometer (DataColor International, Lawrenceville, NJ, USA). RESULTS AND DISCUSSION Colorimetric properties (whiteness degrees, yellowness index and lightness values) of laccase enzyme treated pineapple fabrics are given at Table 1 and Figure 2. Laccase enzyme treatment resulted in slightly yellower appearance leading to less white appearance on pineapple fabrics. Whiteness level slightly decreased in relation to an increase on laccase enzyme concentration whereas absorption capacity increased in relation to the laccase enzyme concentration increment. It is also observed from Table 1, alkali treatment caused slight yellowing effect on the pineapple fibers. It was reported that degradation of chlorophylls, pigments and lignin in the cellulosic fiber structure with alkali solution could cause such yellowing effect (12).
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Table 1. Colorimetric properties and absorption capacities of laccase enzyme treated pineapple fabrics Whiteness Index (Stendsby) 39,74
Yellowness Index (E313) 32,82
L*
Absorption Capacity (%)
80,18
205
Alkali treated
38,48
33,43
76,21
291
% 0.5 Enzyme
33.59
40.9
75.28
289
% 2 Enzyme
32.3
43.53
73.43
306
% 4 Enzyme
30.93
44.54
73.4
328
Non-treated
Figure 1. Colorimetric properties and absorption capacities of laccase enzyme treated pineapple fabrics In Table 2, whiteness degree, yellowness degree and lightness value (L*) of pineapple fabric samples were presented after “acid cellulase A” enzyme treatment. Whiteness levels were not improved after both acid cellulose enzyme treatments. Moreover, cellulase enzyme caused serious fiber damage when enzyme concentration was increased. For this reason, absorption capacity could not be evaluated for %4 “acid cellulase A” enzyme treated pineapple fabric. It is also possible to observe from Table 2, “acid cellulase B” enzyme treatment caused an increase on yellowness level and enzyme concentration was not effective on the yellowing. Both studied acid cellulase enzymes caused yellowing effect on the pineapple fabrics. However, “acid cellulase B” enzyme treatment resulted more yellowing effect. Table 2. Colorimetric properties and absorption capacity of “Acid cellulase enzyme A” treated pineapple fabrics Whiteness Index (Stendsby)
Yellowness Index (E313)
L*
Absorption Capacity (%)
Non-treated
39,74
32,82
80,18
205
Alkali treated
38,48
33,43
76,21
291
% 0.5 Enzyme
33,95
38,16
78,79
320
% 2 Enzyme
36,59
34,78
79,2
364
% 4 Enzyme
40,33
33,06
82,47
-*
*
%4 acid cellulase enzyme treatment caused decomposition of pineapple fabric so the absorption capacity could not be evaluated.
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Table 3. Colorimetric properties and absorption capacity of “Acid cellulase enzyme B” treated pineapple fabrics Whiteness Index (Stendsby)
Yellowness Index (E313)
L*
Absorption Capacity (%)
Non-treated
39,74
32,82
80,18
205
Alkali treated
38,48
33,43
76,21
291
% 0.5 Enzyme
32,5
40,58
76
305
% 2 Enzyme
32,85
39,6
76,89
316
% 4 Enzyme
32,6
39,87
76,49
320
Both Acid cellulase enzymes improved the hydrophilicity of pineapple fabric in relation to an increased enzyme concentration. Absorption capacities of pineapple fabrics after acidic cellulose enzyme treatments were compared in Figure 2. There was an increasing trend for absorption capacities after acid cellulase enzyme applications.
Figure 2. Colorimetric properties of acid cellulase enzyme treated pineapple fabrics
Figure 3. Absorption capacities of acid cellulase enzyme treated pineapple fabrics Neutral cellulase enzyme treatment also decreased the whiteness levels of pineapple fabrics which was similar to the effect of laccase enzyme treatment. Both neutral cellulase enzyme and “acid cellulase B” increased the hydrophilicity of pineapple fabric with fairly similar values.
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Table 4. Colorimetric properties and absorption capacity of neutral cellulase enzyme treated pineapple fabrics Whiteness Index (Stendsby)
Yellowness Index (E313)
L*
Absorption Capacity (%)
Non-treated
39,74
32,82
80,18
205
Alkali treated
38,48
33,43
76,21
291
% 0.5 Enzyme
36,09
37,31
75,73
290
% 2 Enzyme
35,21
38,64
76,48
305
% 4 Enzyme
32,02
41,35
76,43
320
Figure 4. Colorimetric properties and absoption capacity of neutral cellulase enzyme treated pineapple fabrics CONCLUSION After different enzymatic treatments, whiteness and yellowness indexes, absorption capacities of pineapple fibers were evaluated. Consequently, it was observed that cellulase and laccase enzymes caused an increase on the yellowness index and a decrease on the whiteness index of the pineapple fibers. On the other hand, absorption capacities of pineapple fibers were enhanced with an increase on applied enzyme concentration for all studied enzyme types. However, it was also observed that high concentrations of acid cellulase enzyme resulted in a significant damage on pineapple fiber structure. ACKNOWLEDGEMENT The authors extend their appreciation to the Scientific Research Project at Pamukkale University for funding the work through the project PAU-BAP No. 2015-FB020. REFERENCES 1. Kalaycı E, Avinç OO, Bozkurt A, Yavaş A. Tarımsal atıklardan elde edilen sürdürülebilir tekstil lifleri: Ananas yaprağı lifleri. Sakarya Üniversitesi Fen Bilimleri Enstitüsü Dergisi. 2016;20(2):203-21. 2. Mishra S, Mohanty AK, Drzal LT, Misra M, Hinrichsen G. A review on pineapple leaf fibers, sisal fibers and their biocomposites. Macromolecular Materials and Engineering. 2004;289(11):95574. 3. Mohanty A, Tripathy P, Misra M, Parija S, Sahoo S. Chemical modification of pineapple leaf fiber: Graft copolymerization of acrylonitrile onto defatted pineapple leaf fibers. Journal of applied polymer science. 2000;77(14):3035-43.
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