Plasma technology in wool

The textile industry processes a large quantity of fibres obtained from various animals of which wool is commercially the most important. However, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling and dyeability. These problems may be attributed mainly to the presence of wool scales on the fibre surface. The scales are relatively hard and have sharp edges which are responsible for causing fibre directional movement and shrinkage during felting. Furthermore, the scales also serve as a barrier for diffusion processes which will adversely affect the sorption behaviour. In recent years, there has been an increase in the modification of wool surface scales by physical means such as mechanical, thermal and ultrasonic treatments, and chemical methods such as oxidation, reduction, enzyme and ozone treatments which can solve the felting and sorption problems to a certain extent. Hitherto, chemical treatments are still the most commonly used descaling methods in the industry.

Owing to the effect of pollution caused by various chemical treatments, physical treatments such as plasma treatment have been introduced recently as they are capable of achieving a similar descaling effect. Since the 1960s, scientists have successfully exploited plasma techniques in materials science. The plasma technologies have been fully utilised to improve the surface properties of fibres in many applications. The fibres that can be modified by plasmas include almost all kinds of fibre such as textile fibres, metallic fibres, glass fibres, carbon fibres, fabrics and other organic fibres.

Plasma-treated wool has different physical and chemical properties when compared with the untreated one. The changes in fibre properties alter the performance of the existing textile processes such as spinning, dyeing and finishing to produce a series of versatile wool products with superior quality. Therefore, the aim of this monograph is to give a critical appreciation of the latest developments of plasma treatment of wool. In this monograph, different surface treatments of wool including plasma treatment will be precisely described. Since plasma treatment can be used to alter material surfaces by removing outer layers, thus the method of generation of plasma and the reaction mechanisms between material surface and plasma species will be highlighted in this monograph. Similar to other chemical reactions, the factors such as (i) the nature of gas used, (ii) gas flow rate, (iii) system pressure and (iv) discharge power affecting the final results of plasma treatments will be described.

The main content of this monograph includes the application of plasma treatment on wool under different industrial conditions such as dyeing and shrinkproofing processing which will be reported and discussed respectively. In addition, the common analytical methods such as Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy with Attenuated Total Internal Reflectance mode analysis employed for characterising the surface properties of plasma-treated wool will be discussed. Based on the surface characterisation results, more details about the mechanism of plasma treatment that affects the wool processing such as dyeing and shrinkproofing can be explored.

In the latter part of the monograph, the serviceability of plasma-treated wool fabrics is discussed and the possibility of applying the plasma-treated wool fabric to industrial use is evaluated based on standard performance specification, e.g. ASTM. The fabric performance in terms of tailorability and sewability are also discussed with reference to the Kawabata Evaluation System for Fabric (KES-F) results. As the plasma process is a “dry” process, i.e. the water used in the plasma system can be recycled, thus it can solve the industrial effluent problem resulting in providing an effective means for the modification of wool fabrics.     

Effect of chemical treatments of sugar beet fibre on their physico-chemical properties and on their in-vitro fermentation

Chemically treated and dried sugar beet fibres were fermented in vitro in order to study the effects of chemical and physico-chemical parameters of dietary fibre on their colonic fermentation. Sugar beet fibre was treated with dilute alkali, removing mainly acetyl and methyl ester groups, and/or with dilute acids eliminating arabinose, galactose and certain uronic acid residues. The chemical treatments led to an increase in the hydration properties and fermentability by improvement of the accessibility of the remaining polysaccharides. However, if the chemically treated fibres were dried under harsh conditions (100°C), their hydration properties and their fermentability were limited, probably because of structural collapse of the fibre matrix. Whatever the conditions for chemical treatments and drying of the sugar beet fibres, it was possible to predict their fermentability from the water-binding capacity. Because of the relationship between the physiological effects of dietary fibres and the extent to which they are fermented, this result underlines the importance of the physico-chemical characterisation of the fibre in order to acquire a better knowledge of their physiological effects.     

Application of transglutaminase to derivatize proteins: 1. Studies on soluble proteins and preliminary results on wool

The use of enzymes in chemical processing is gaining favour due to the reduction of hazardous chemicals and because it is considered to be environmentally safe. The acyl transfer reaction between primary amines and glutamine residues in proteins is catalysed by the enzyme transglutaminase. The efficiency of microbial transglutaminase to attach functional amines and catalyse inter‐ and intra‐molecular crosslinks was investigated using reduced carboxymethylated κ‐casein, gelatin and wool. Model systems used in this research gave evidence of both cross‐linking of the protein and covalent binding of the primary amine o‐phosphorylethanolamine to the protein. These data agree with earlier publications that show transglutaminase catalyses the formation of covalent cross‐links between the γ‐carboxyamide group of glutamine and the ε‐amino group of lysine and also the incorporation of primary amines into proteins. Preliminary analysis of treated wool indicated the covalent bonding of the functional amine to the protein. Our goal is to increase the value of wool by enzymatic addition of functional groups to the wool fibre. Published in 2004 for SCI by John Wiley & Sons, Ltd.     

Comparisons of the Fourier Transform Infrared Spectra of cashmere,guard hair,wool and other animal fibres

Fourier Transform Infrared Spectroscopy (FTIR), identifies chemical bands related to chemical bonds including amino acid groups. The potential for FTIR to differentiate animal fibres from different origins was investigated using cashmere (Chinese, Australian, Iranian), wool (Chinese, Australian), bison wool, qiviut from Musk-ox, vicuña and guard hairs present in these raw fibre samples. Cashmere from a controlled nutrition experiment with known amino acid composition was included in the study. While the intensity of FTIR spectra were moderately correlated with the content of some of the amino acids in cashmere, this investigation did not detect any significant systematic effects of nutritional manipulation of cashmere goats on the FTIR spectra of their cashmere. Significant differences were detected in the intensity of FTIR spectra between cashmere and wool, cashmere from different origins, white and coloured cashmere, and between cashmere and hair. The FTIR spectra of cashmere and wool overlapped with those of bison, qiviut and vicuña. The intensity of FTIR spectra were not correlated with the mean fibre diameter of samples but the intensity of most spectra bands were positively correlated with the fibre curvature of the samples (r = 0.27–0.38). Based on these results it does not seem likely that FTIR spectra offer a reliable method to distinguish between pure cashmere and blends of cashmere with wool or other animal fibre for diagnostic tests to determine the fibre composition in finished textiles.     

12—THE FORMATION OF LYSINOALANINE AND LANTHIONLNE IN WOOL FIBRES STRETCHED IN BOILING WATER,AND THEIR RELATION TO PERMANENT SET

When wool fibres are held at 40% extension in boiling water for increasing periods of time, there is a progressive decrease in their cystine contents with concomitant increases in their lanthionine and lysinoalanine contents. After 3 hr, the contents of these amino acids have reached a maximum, which coincides with the maximum retention of set. At this time, approximately 24% of the cystine residues have been modified.

The mechanism of set is a complex phenomenon involving conformational changes in the proteins constituting the microfibril–matrix structure of the wool fibre. Whereas the results in this paper support the cross-linkage-stabilization theory of set postulated by Speakman, their implications, both for this and for the thiol–disulphide-interchange theory of set, are discussed in the light of modern ideas on the structure of wool.     

20—PURPOSE-GROWN WOOLS. PART I: MODIFICATION OF THE FELTING PROPERTIES OF WOOL THROUGH THE SHEEP'S FEED

A method is described whereby the shrinking property of wool can be modified during growth by the administration of chemical additives to the sheep's diet so as to enter the character of the fibre half-way through the growth of the staple. Thus, hard-root-soft-tip fibres can be grown to enhance shrinkage and soft-root-hard-tip fibres to impart shrink-resistance. Methods of modifying the shrinkage of wool have so far been confined to chemical treatments of the shorn fibre, but this original approach to shrinkage control also presents an opportunity for the mass production of a large variety of other types of special-purpose wools.     

IMPROVEMENT OF THE NATURAL FLAME-RESISTANCE OF WOOL PART II: MULTI-PURPOSE FINISHES

Isopolytungstates and heteropolytungstates improve the flame-resistant effect of the fluorozirconate application on wool. Wool treated with isopolytungstates discolours on exposure to light, whereas with some heteropolytungstates no discoloration occurs. The zirconium–tungsten applications are suitable for wool treated by chemical shrink-resist treatments, which has a slightly decreased flame-resistance owing to partial degradation of the fibres. Fully washable and flame-resist wool can be achieved by the application of resins with a similar or higher LOI value than wool and by treating the fibre with zirconium and tungsten complexes.

Wool-bleaching is compatible with a zirconium after-treatment. The zirconium and titanium complexes are compatible with mothproofing and water- and oil-repellent agents, and in some cases a one-bath application is possible to achieve various multi-purpose finishes.     

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

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

Improve the functional properties of dietary fibre isolated from broccoli by-products by using different technologies

The aim of this study was to analyze the chemical composition of leaves, stems and inflorescences obtained from broccoli by-products in order to develop the improvement of the composition and functional properties of DF from broccoli by-products through treatment with different degradation methods, such as modifications with supercritical fluids, enzymatic, autoclave and ultrasound treatment. The results showed that the chemical composition of the different parts of the broccoli by-products, leaves, stems and inflorescences was significantly different, highlighting that the content of insoluble and soluble dietary fibre was higher in the stem. The enzymatic treatments decreased the content of neutral sugars and increased the content of uronic acids, which was related to the increase of specific functional activities. Cellulase and the multi-enzymatic visconzyme complex improved the solubility and glucose adsorption capacity, whereas supercritical fluids treatment improved the swelling, water retention and lipid absorption capacities. The value of non-extractable phenolic compounds was higher in the inflorescences and increased with enzyme and supercritical fluid treatments, as well as the antioxidant capacity. Enzyme treatment also had a greater effect on the stimulation of the growth of the lactic acid bacteria studied and, therefore, reached the highest values in the production of all short-chain fatty acids analysed. Therefore, the use of enzyme treatments of dietary fibre obtained from broccoli by-products improves the functional properties of broccoli fibre.     

Chemical composition and functional properties of Ulva lactuca seaweed collected in Tunisia

The chemical composition and some functional properties of the dried “Ulva lactuca” algae, collected from the littoral between the Taboulba and Sayada area, were determined. The dried “U. lactuca” algae were investigated for their soluble, insoluble and total dietary fibre content, mineral amount, amino acid and fatty acid profiles, swelling capacity (SWC), water holding capacity (WHC) and oil holding capacity (OHC). Results showed that “U. lactuca” alga powder was characterised by a high content of fibres (54.0%), minerals (19.6%), proteins (8.5%) and lipids (7.9%). The neutral fibres contain hemicellulose (20.6%), cellulose (9.0%) and lignin (1.7%). The proteinic fraction analysis indicated the presence of essential amino acids, which represent 42.0% of the total amino acids. The fatty acids profile was dominated by the palmitic acid, which represents about 60.0% of the total fatty acids, followed by oleic acid (16.0%). The study of the functional properties proved that SWC, WHC and OHC of this alga varied with temperatures and that were comparable to those of some commercial fibre rich products.     

Comparison of the affinity and selectivity of insoluble fibres and commercial proteins for wine proanthocyanidins

The fining action of commercial proteins and insoluble fibres for wine proanthocyanidin (PA) were compared. Fibres were prepared from fresh apple and grape sources, and their corresponding pomaces. PA removal by fibre was via adsorption, and required a higher dose to achieve a fining effect comparable with proteins. A principal component analysis data model revealed that PA molecular mass was significant in defining the fining response, and reflected changes in the proportion of the dominant terminal PA subunits catechin and epicatechin, but not epicatechin-3-O-gallate. For PA extension subunits, changes in epigallocatechin were inversely correlated with epicatechin and epicatechin-3-O-gallate. Generally, the application of proteins and fibres reduced PA molecular mass. Selectivity for PAs by subunit composition was variable between treatments, but differences were minor. This work demonstrates the potential use of fibres as an alternative to proteins in winemaking. Benefits, and possible limitations of such an approach are discussed.     

Influence of the dehydration process on active compounds of okara during its fractionation

Okara (residue of the soymilk manufacture) is rich in proteins, fibres and lipids. It also contains isoflavones that possess health‐promoting properties. A new method has been developed for the valorization of fibres from okara by hydrolysis of insoluble proteins with a protease and removal of the oil. Three different processes were investigated: the first one involved delipidation and drying prior to proteolysis and led to the highest content of fibre (80%) in the final product. The second used proteolysis on crude okara followed by solvent delipidation–dehydration and gave an intermediate content of fibre (75%). The last process was totally enzymatic (proteolysis and lipolysis) and gave the lowest content of fibre in the final product (50%). Fibre water‐holding capacity was correlated to the total dietary fibre content of each sample. It was preferable to use crude okara for hydrolysis, since oven‐drying during the process decreased the water‐holding capacity and modified the isoflavone profile of okara. Copyright © 2005 Society of Chemical Industry     

The Effect of Snippet Length on the Estimation of Wool-fibre Diameter by the Projection-microscope Method

A study is reported of the adsorption mechanism of two ionic surfactants (sodium dodecyl sulphate and hexadecyl trimethyl ammonium bromide)on wool in relation to the temperature or time of treatment, either in aqueous or in aqueous-ethanolic media. From the results obtained, the effects of these ionic surfactants on acid and alkaline treatments of wool were evaluated by the alkali-solubility test, determination of the cystine content of the fibres, and analysis of the new amino acids formed during the treatment of wool fibres with methylamine or dimethylamine.     

Dyestuff—fibre interactions

The strength and nature of dye–fibre interactions vary according to fibre type and dye type. In the case of acid dyes for polyamide fibres, cationic dyes for acrylic fibres, disperse dyes for hydrophobic fibres, and direct dyes for cellulosic fibres, these interactions may be classified as non-covalent, a classification which includes van der Waals (VDW), electrostatic, induction, solvophobic and charge-transfer interactions.
Reactive dyes are a notable exception to the above, since the interaction which is responsible for their excellent wet fastness is the dye–fibre covalent bond, however, these dyes are increasingly viewed as environmentally unfriendly due to high salt usage and residual unfixed colour. This situation may be improved by either incorporating amine sites in the cellulose or by reversing the system to incorporate reactive residues in the fibre and nucleophilic sites in the dye.
Nonionic disperse dyes are valuable for hydrophobic fibres such as polyester but have made little impact on hydrophilic fibres such as silk, wool and cotton. Experiments to develop simple treatments to render the latter fibres disperse dyeable are described and the combined role of solvophobic and – interactions discussed.     

不同预处理对蚕蛹制备呈味基料风味的影响

以鲜蚕蛹为原料,采用漂烫灭酶、脱衬模拟、脱衬模拟+烘干三种方式对原料进行处理,通过酶解及美拉德反应制备蚕蛹呈味基料,研究不同处理对蚕蛹的脂肪酸、酶解产物的水解度及氨基酸、美拉德反应产物的感官风味等指标的影响。结果表明,三种处理方式均能提高蚕蛹呈味基料的感官风味,但不同处理方式的风味存在不同程度的差异。其中漂烫灭酶处理的产物风味最好,其脂肪酸组成及含量变化不大,酶解液水解度最高(23.88%),肽类鲜甜味氨基酸占总鲜甜味氨基酸的比例亦在三种处理方式中最高(高达76.90%),酶解液美拉德反应产物的肉香味有所增加,苦味和蚕蛹本身的腥臭味均被除去,共鉴定出挥发性风味化合物26种,其中醛类9种、吡嗪类6种、呋喃类3种、其他化合物8种。     

Enzymatic Finishing of Wool Fabrics

SUMMARY

The objective of the present work is to evaluate the action of a protease when applied on a high quality wool fabric to obtain an improved touch and drape on the fabric as well as to decrease its shrinkage and pilling propensity.

The effectiveness of the enzymatic treatment as well as the intensity of the attack to the wool fibre are evaluated by determining several mechanical and chemical parameters.     

Innovative critical solutions in the dyeing of protein textile materials

Even though animal fibres contribute a comparatively low proportion of world fibre production, they are highly sought after and play a significant role in the luxury, high value-added end of the market. Natural protein fibres have two major classes, which may be categorized as keratin fibres (hair or fur), such as wool, cashmere, and other animal hairs, and secreted (insect) fibres with silk as the main fibre in this category. Colouration of protein fibres is characterized by many variables, each with a different effect on the final product. Indeed it is quite complicated to achieve the intended colour in the first dyeing attempt. Dyeing defects are not always due to the actual dyeing process, but may be introduced in earlier production and processing stages. This work attempts to provide a detailed review of the major issues in the dyeing of various protein textile materials in different forms such as loose fibre, yarn, fabric, and garment. An overview of different types of protein fibres is given and a summary of current industrial practices for the dyeing of protein fibres is provided followed by key variables that affect the control of colour in the dyeing of protein fibres. Key steps and critical factors involved in the production of dyed protein textile materials are described in detail and solutions to the problems that may arise at each stage are provided.     

Use of low‐level plasma for enhancing the shrink resistance of wool fabric treated with a silicone polymer

This study examines the effects of an atmospheric pressure plasma (APP) pre‐treatment on the shrink resistance of wool fabric treated subsequently, by the pad/dry method, with an aqueous emulsion of the amino‐functional polydimethylsiloxane, SM 8709. Optimal shrink resistance (with no impairment of fabric handle) was obtained after a low‐level plasma treatment (1–3 s exposure time), using 5% of the polymer emulsion. Higher levels of silicone polymer could be used to achieve shrink resistance in the absence of a plasma pre‐treatment, but the fabric handle would be adversely affected. X‐ray photoelectron spectroscopy (XPS) studies showed that the bulk of the covalently bound surface lipid layer was removed after a plasma exposure time of 30 s. For treatment times of 3 s or less, however, the removal was incomplete, suggesting that optimum shrink resistance (after treatment with the silicone polymer) was associated with the modification of the surface layer rather than its complete destruction. Scanning electron micrographs (SEMs) revealed that the plasma pre‐treatment did not lead to any physical modifications (such as smoothening of the scale edges), even for long exposure times, and had no significant impact on the extent or nature of the inter‐fibre bonding of the polymer. Confocal microscopy showed uniform spread of polymer on single fibres. It is concluded that the main impact of the plasma pre‐treatment was to enhance the distribution of polymer both on and between fibres and to improve adhesion of polymer to the fibre.     

The Role of Muscle Proteases and Lipases in Flavor Development During the Processing of Dry-Cured Ham

The processing of dry-cured ham is very complex and involves numerous biochemical reactions that are reviewed in this article. Muscle proteins undergo an intense proteolysis, resulting in a great number of small peptides and high amounts of free amino acids. The enzymes responsible of these changes are proteinases (cathepsins B, D, H, and L and, to a less extent, calpains) and exopeptidases (peptidases and aminopeptidases). Muscle and adipose tissue lipids are also subject to intense lipolysis, generating free fatty acids by the action of lipases that, in a second stage, are transformed to volatiles as a result of oxidation. Sensory profiles of dry-cured ham are strongly affected by these enzymatic reactions. In addition, the activity levels of the muscle enzymes significantly depend on the properties of raw ham, such as age and crossbreeding as well as the process conditions such as temperature, time, water activity, redox potential, and salt content. Thus, the control of the muscle enzyme systems, mainly proteases and lipases, is essential for the standardization of the processing and/or enhancement of flavor quality of dry-cured ham.     

Damage of Amino Acid Residues of Proteins after Reaction with Oxidizing Lipids: Estimation by Proteolytic Enzymes

A mixture of casein and methyl linoleate was stored at 50°C and 80% relative humidity for 0 - 14 days and damage to amino acid residues assessed. The damage was estimated by determining the amino acid composition of the hydrolysate by using proteolytic enzymes (pepsin-pancreatin digestion, followed by aminopeptidase-prolidase hydrolysis). The damage to amino acid residues was the most extensive in methionine, followed by tryptophan, histidine, and lysine. The degree of damage to these amino acids was also determined by chemical methods without using proteolytic enzymes. The efficiency of detecting damage by the present enzymatic method was close to that of the chemical methods.