Page 289 - Advances in Textile Biotechnology

270 Advances in textile biotechnology

and Bhattacharya, 2008; Rao and Srivastava, 1973). Repeated alcohol pre-
cipitation and dissolution, sometimes employing chemical or enzymatic
treatment steps (Rao and Srivastava, 1973), can be used to prepare high-
purity fractions of XG polysaccharide for diverse applications, including
thickeners, stabilizers, or gelling agents in food and pharmaceutical prod-
ucts (Coviello et al., 2007; Gerard, 1980; Kumar and Bhattacharya, 2008;
Yamatoya and Shirakawa, 2003).

11.3 Technical uses of native xyloglucans in
cellulose modifi cation
11.3.1 Applications in textiles and papermaking

XG, extracted from tamarind kernel powder (TKP) in various purities, has

long been used to modify cellulosic fibres from cotton, jute, and wood,
especially in India, where the tree is indigenous (Gerard, 1980; Kumar and
Bhattacharya, 2008; Rao and Srivastava, 1973; Shankaracharya, 1998).
Sizing cotton, jute, and spun viscose with TKP improves yarn strength
during weaving and imparts smoothness and stiffness to fabrics (Gerard,
1980; Kumar and Bhattacharya, 2008; Rao and Srivastava, 1973). Here, XGs
are competitive with, or superior to, starches, and the strengthening effects
are likely, at least in part, to be the result of fi bre–fibre crosslinking medi-

ated by the specific interaction of XG with cellulose. XG can also act as a

functional barrier coating for cellulose fibres: adsorption of XG on to yarns
or fabrics before dyeing, followed by treatment with a xyloglucanase (XG-
hydrolyzing enzyme) enhances partial dye removal, creating a desirable
abraded look (Kalum, 1998).
Regarding wood fibres, tamarind XG has been used in a crude form as a

binder for sawdust briquette and plywood manufacture, whereas, in combi-
nation with cross-linking borate salts, the polysaccharide gum has been used
as a paper adhesive (Gerard, 1980; Kumar and Bhattacharya, 2008; Rao
and Srivastava, 1973; Shankaracharya, 1998). The use of TKP to replace
starches and galactomannans for the improvement of paper strength prop-
erties has been long known (Gerard, 1980; Rao and Srivastava, 1973; Shan-
karacharya, 1998). More recently, the ability of XGs to improve paper
properties has been re-examined using contemporary approaches. Isolated
tamarind XG binds to chemical wood pulp fibres in aqueous suspension

with high affinity, improving both strength properties as well as fi bre distri-

bution (formation) in paper sheets (Christiernin et al., 2003; Lima et al.,
2003). In addition to wet-end application, XG has also been applied as a
spray coating, where the polysaccharide gives considerably higher improve-
ments in sheet strength properties for similar loading amounts (Ahrenstedt
et al., 2008).

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