Quality Improvement in Jute and Kenaf Fibre

H.S.Sen1

Former Director, Central Research Institute for Jute & Allied Fibres

(ICAR/DARE, Government of India), Barrackpore, North 24 Parganas

West Bengal, India, PIN 700 120

(Email: , )

Abstract

Future of raw jute fibre consisting of Corchorus and Hibiscus species lies mainly through quality improvement for diversified and value-added uses. This can be achieved in three broad ways, viz. (1) technical processing, (2) genetic manipulation, and (3) cultural along with retting practices. The paper presents following a brief discussion on the role of fibre quality improvement for various diversified products, the factors influencing quality parameters, their limitations in applications,andfuture thrust areas.

Commensurate with the expected rise in production of jute and kenaf by 3-4 times in 2050 of the present value there is a need for proportionately higher attention for improved yarns to meet product specific quality norms for the manufacture of (i) high quality blended apparel grade textiles, (ii) Technical, industrial and home textiles including non-woven, (iii) automotives, (iv) soil savers, (v) bio-composites, (vi) pulp and paper, (vii) fine chemicals, cosmetics and healthcare products, and (viii) bio-fuels. Technological upgradations are required for meeting the prescribed limits with consistency in quality.

Improvement in fibre quality either genetically or by improving technological processing, or through improved cultural practices is of prime concern. This will enhance the demand for jute yarns. We generally concentrate on improving texture, colour, weight per unit reduction, hairiness, low extensibility, poor abrasion resistance, etc. in order to improve the quality. The principal uses for jute yarns are for industrial purposes in which adequate strength is normally regarded as essential. Appearance, colour and other attributes are however of relatively lesser significance. It is now regarded that the yarn should be of finer counts (6 lb/ spy and below) which should be not only quality- but also cost-competitive so as to attract the market. On the other hand, such yarns should be converted to light, dense and strong hessian fabrics for ready acceptability to the market and higher financial return. This is a technological challenge for those engaged in industry to achieve the above targets.

From plant anatomical point of view the length-breadth ratio (L:B) of ultimate fibre cells has a definite bearing on fibre quality. Higher the ratiofiner is the fibre.

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1Present address: 2/74 Naktala, Kolkata, West Bengal, India, PIN 700 0047

Some wild species have been identified as prospective donors to impart higher L:B

ratio vis-a-vis finer fibre through appropriate breeding practice. Similarly, there are someotherwild species which mayalso impart finer fibrequality. High lignin content in thesefibres is responsible for colour instability, which is a distinct disadvantage in the dyed products. Reducing lignin content to the optimum level by genetic manipulation is, therefore, logical. Detailed studies on a jute mutant, ‘deficient lignified phloem fibre’ (dlpf), suggested its usefulness to engineer low-lignin jute variety. Genetical manipulation is a very important approach to achieve the targeted quality improvement. Assemblage of genes on the jute chromosomes is very poorly understood. It is now necessary to focus on developing linkage map of olitorius jute, in particular, to start with, which would help in preparing an integrated map using molecular map data on the species. In kenaf, cytological studies of various inter-specific cross derivatives established the genome constitution of H. cannabinus L., a diploid, indicating a genomic relationship between this species and H. radiatus L. H. sabdariffa L. is, however, an autotetraploid. It is extremely important to make note of the fact that modern biotechnological methods and tools in combination with traditional approaches through marker assisted selectionhave the potential to achieve product specific quality improvements in future calling for international network of activities as happened in few other crops, mainly cereals.

Improvement of cultural practices, particularly retting, is considered another very important approach, which should be user-, cost-, as well as environment-friendly, for quality upgradation of the fibres for both these crops.

In terms of constraints to achieve the targets stated above it is imperative, from technological point of view, to develop some suggested machineries and quality monitoring instruments, and, from the point of view of plant research, adequate fund and international network activities for studies on jute and kenaf genome with well-targeted programme.

Introduction

Favourable conditions for jute cultivation are found in the deltas of the great rivers of their tropics and sub-tropics - the Ganges, the Irrawaddy, the Amazon, and the Yangtze, for example, where irrigation, often by extensive flooding, and alluvial soils combined with long day lengths prevail. The crop however thrives very well under rainfed and hot humid and sub-tropical conditions in the BengalBasininIndia and in Bangladesh where more than 80 % of the crop of the world is grown. Comparatively, kenaf requires less water to grow than jute and is now grown in several countries in Europe, Africa, South America, Mexico, the United States, Japan and China. Both jute and kenaf reach 2.5-3.0 m in height at maturity; but kenaf, although still requiring a longer day length for vegetative growth, flourishes in drier conditions than jute can, and can adapt to a wider variety of soils and climates. As a result, it has often been preferred to jute as a fibre crop by many countries in Africa and Latin America, although usually for internal consumption. Significantly, kenaf (H. cannabinus) plantation (if grown in high density) has been recorded to fix about twice the amount of CO2 as compared to forest plantation thereby contributing to global and regional environment (Lam et al., 2003).

The specifications and standards of classic jute products have remained unchanged for decades. The traditional products are dominated by sacks (nearly 50 %), though improved ‘food bags’, devoid of mineral oil, meant for cocoa and coffee beans have been developed out of these sacks. Next is hessian (< 20 %), yarn for carpet & twines (≈ 20 %), hessian for CBC (≈ 2 %), and other items including soil savers, jute woven matting, bags, decorated farics, etc. (≈ 10 %). Commensurate with the expected rise in production of jute and kenaf by 3-4 times in 2050 of the present value there is a clear need for proportionately higher attention to non-traditional diversified products. It is prudent that for jute industry to survive and possibly flourish with a much brighter future it should take recourse to this non-traditional group of products which will require generally the improved quality fibres. The product specificities of a variety of these products have been documented (Hazra and Karmakar, 2004; Karmakar et al., 2008), but needs lot more work for refining for each area of application. The manufacture of diversified jute products requires the use of best grades of raw jute in most cases, more capital investment, higher textile levels of design and market skill, more capable and focused mill management, a degree of entrepreneurship above and beyond that usually found in the traditional industry, and on the top of that, considerable R&D expenditure. The real future, however, lies in the area of technical textiles (Roy, 2008).

The improved yarns are needed to meet product specific quality norms for the manufacture of (i) high quality blended apparel grade textiles, (ii) Technical, industrial and home textiles including non-woven, (iii) automotives, (iv) soil savers, (v) bio-composites, (vi) pulp and paper, (vii) fine chemicals, cosmetics and healthcare products, and (viii) bio-fuels. Technological upgradations are required for meeting the prescribed limits with consistency in quality also. This can be achieved in three broad ways, viz. (1) technical processing, (2) genetic manipulation, and (3) cultural along with retting practices. The paper presents following a brief discussion on the role of fibre quality improvement for various diversified products, the factors influencing quality parameters, theirlimitations in applications, and future thrust areas.

Quality improvement and scope for uses

Plant anatomy: fibre structure

Tossajute, white jute, H.S.mesta, and H.C.mesta fibres are arranged in the bast or phloem region of the plant consisting of pyramidal wedges which taper outwards; the fibre bundles in each wedge are arranged in 8-24 layers, alternating with groups of thin walled phloem.The bast fibre strands form a tubular mesh that encases the entire stem from top to bottom. This is looser towards the top of the stem becomingprogressively more compact towards the basal region where again meshiness is looser towards the outside of the stem but much more compact towards the region near the cambium (Kundu, 1954; Kundu et al., 1959; Maiti, 1980,1997). The meshiness is more in both mesta species than in jute. It is well known that meshiness is an obstacle to carding process, which is done to break up the fibre sheath as a preliminary to spinning, and thus for finer quality yarn preparation.

Properties

The fibres of jute and kenaf are lingo-cellulosic in nature, multi-cellular with single cells embedded in a matrix composed of non-cellulosic matters, and lignin constitutes one of the primary components in the system. The end use application of these fibres primarily depends on their physical, structural and chemical properties.

Following are the salient characteristics for jute and kenaf vis-à-vis other fibre crops required for consideration to improve the fibre quality of the former group (Sreenivasan, 2004).

  1. High variations in length and diameter are found to be inherent features.
  2. Variability in tensile characteristics like breaking load and extension is quite high.
  3. No significant drop in tenacity was noted during wetting of each except flax.
  4. Efforts to increase the fineness by chemical treatments lead to deterioration in tensile properties indicating the strong role of binding materials.
  5. Moisture regain values have been noted to be very high indicating their comfort character.
  6. Breaking extension is found to be highly correlated to the spiral angle.
  7. The amorphous and crystalline regions is of low order in jute and kenaf, as compared to ramie, as shown by high birefringence values recorded in ramie.
  8. Cellulose content is lower but hemi-cellulose content is much higher in jute, as compared to those in ramie and flax, the latter group known to yield improved quality decorticated fibres.
  9. Lignin content is also much higher in jute, as compared to that in ramie and flax, the latter group known to yield improved quality decorticated fibres.

Diversified jute goods

The demand prospect for exportable jute yarn is the brightest spot in export chain. Bangladesh has led over other countries in respect of quality jute fibre production and its export. In India, however, export of JDPs constituted around 27% of total jute goods export in 2003-04. Amongst JDPs, floor covering was the most dominant (Rs. 95.44 crores in 2003-04), followed by hand and shopping bags (Rs. 95 crores in 2003-04) and home textile made-ups. Except jute geo-textiles, all the items mentioned above basically require higher quality fibre, which is inadequately available in India.

Major areas of diversified use are:

  • Blended textiles
  • Technical, industrial and home textiles including geotextiles, both woven and non-woven
  • Bio-composites
  • Pulp and Paper
  • Healthcare
  • Biofuel, energy and other uses

Fig. 1. Added value versus mass potential of bast fibre products (Kessleret al.,)

Fig.1 shows a selection of potential oftextile and non-textile products and their added values. As can be seen from the graph, textile products usually show higher mass potential and higher added value in comparison to technical applications. The demands in technical applications are much higher at lower costs. Nevertheless, man-made fibres can be designed specifically suiting to the individual application and also that the quality can be guarantied year by year.

Plant biomass utilization as by-products

It is well known that huge plant biomass is produced while growing jute and kenaf for fibre purpose. Fibre constitutes only 4-6% of the total biomass, while sticks (generally used as fuel source) contribute the most, and the rest (except seed) is never utilized. The available information (Hazra et al., 2008) strongly suggest that these plant parts have got great potentials for product diversification, which are given below (Table 1), apart from those mentioned in the preceding sections.

Table 1. Plant biomass utilization as by-products

Crop / Plant parts / Application areas/ chemicals
Jute / Seed / Seed oil (8.2 to 11.9%) for industrial uses
Leaf, stem, seed, root and whole plant / Direct medicinal uses; contain 18 phamaco-dynamic compounds suitable for drug development
Kenaf / Seed / Seed oil (21.44%) for industrial uses
Leaf, stem, seed, root and whole plant / Direct medicinal uses; contain 14 phamaco-dynamic compounds suitable for drug development
Calyx / Jam, jelly, sauce, chutneys and natural colours
Jute and Kenaf
(H. S. mesta and H. C. mesta) / Sticks / Paper pulp, oxalic acid, furfural, charcoal, viscose rayon, Carboxymethyl Cellulose (CMC) & microcrystalline cellulose (MC)

Efforts towards promotion of JDP

As a measure of support to jute industry, Government of India enacted a special legislation called the Jute Packaging Materials (compulsory use in packing commodities) Act, 1987 under which the Government from time to time issues notified order specifying the commodities to be packed compulsorily in jute bags. The use of jute bags underthis Act has started getting diluted phase-wise. The jute sector thus can’t indefinitely depend upon such a protected marketing condition – and more dilution of this act is a certainty in future. The industry has to develop itself to withstand the competition being thrown up by synthetics particularly in the WTO regime. Product diversification is one of the major options for their sustenance. Lately, Government of India instituted a comprehensive Jute Policy subsequent to which The Jute Technology Mission (JTM) became operational. Very recently, Government of India announced, as a sequel to this move, formation of National Jute Board for more concerted and integrated attention for the promotion of this family of crops.

Similarly, the Government of Bangladesh made an all out effort to resolve the issue for promotion of improved quality of fibres through Jute Diversification Promotion Centre (JDPC) since 2002 with the mandate to achieve its objectives both regionally and globally. A high level national task force has been constituted to recommend appropriate measures to salvage jute sector out of its present economic crisis. In an endavour to give further thrust in this direction, JDPC was made stronger with the support of Delegation of the European Commission, while in order to redefine its goals and objectives. Accordingly, National Jute Policy-2008 has been adopted by the government with the renewed objectives to attain and sustain a pre-eminent global standing in the production of raw jute and in the manufacture and export of jute goods. It also seeks to strengthen R&D activities in agricultural practices with a vision to ensure remunerative prices to the farming community.

Grading and classification

Different countries have got different systems of grading. For jute fibre exported from Bangladesh, for example, the current grading system first separates C. capsularis and C. olitorius into white and tossacategories, respectively and then further classifies each into six grades denoted by the letters A to E and one of ‘Special’ category. The highest price is paid for Grade A, although for a special grade higher price may be demanded. Similar system of grading subjectively is in vogue in India also, where the earlier classification into 8 categories, i.e. TD1-TD8 for tossajute and W1-W8 for white jute has recently been revised to 6 categories in each, subject to acceptance by the government, for better understanding and higher transparency. Likewise, China has got 4 grades, Indonesia 3, and Nepal 2 grades of fibre classification.

The principal criteria are colour, lustre, strength, cleanliness, and freedom from retting defects (Rowell and Stout, 1998).Two major parameters of fibre quality, i.e. strength and fineness are genetically controlled. From spinning point of view, colour is irrelevant but certain end users traditionally prefer fibres in particular colours for the sake of appearance. Lustre is commonly an indication of strength: if, for example, the fibreisover-retted, the cellulose or middle lamella is attacked and weakened, the surface will then appear dull. A lack of lustre thus downgrades the fibre although occasionally this same effect may result from inadequate washing, without any loss of strength. Strength of fibre is also assessed by snapping a few strands by hand, a procedure that gives a useful indication of quality to an experienced operator. Cleanliness and freedom from non-fibrous matter is an important feature. In this respect, the physical imperfections that may result from improper retting can have a profound effect on the allotted grade. Adhering bark in any form results in downgrading, irrespective of the intrinsic value of the fibre; and in the case of plants grown on flooded land, which stand in water, the bark becomes so difficult to remove that, for export, the root ends are cut off and sold separately as “cuttings,” to be used in heavy yarns of low quality.