Page 161 - Advances in Textile Biotechnology

142 Advances in textile biotechnology

cellulases, alone and in mixtures, were examined for their influence on wax
and pectin removal (Ismal, 2008). The results showed that all treatments
created fabrics giving less than 3 s in the AATCC 79 water drop test method
(AATCC, 2009). All the enzymatic treatments gave better hand (soft feel
of the fabric) than alkaline scouring, and the weight losses for the enzymatic
treatments were all less than those in alkaline scouring.
A comprehensive study by the group at the University of Twente in the
Netherlands has also addressed the question of the essentials needed for
enzymatic scouring (Agrawal et al., 2007). A TRI auto porosimeter (Miller
and Tyomkin, 1994) was used to study changes in hydrophilicity. The poro-
simeter was said to have the advantage over the commonly used AATCC
drop test and various absorption tests in that the results are independent
of fabric density and structure. From these measurements they were able
to calculate a structural contact angle. The research group used these cal-
culations to benchmark the effects of enzymatic treatments against stan-
dard alkaline scouring. From this work they concluded that wax and pectin
removal were the essentials for scouring, and that in the enzymatic pro-
cesses the removal of the outermost layer of wax was foremost. Another
report from this group introduced a cutinase–pectinase mixture, combined
with added mechanical action, that allowed them to reduce the scouring
temperature from 50 °C with pectinase to 30 °C with the mixture (Agrawal
et al., 2008).

6.5.3 Cotton seed coat fragment removal by
enzyme treatment
The complex nature of the chemical and physical structures of cotton seed

coat fragments ensures that finding an enzymatic route to removing and/or
decolorizing these contaminants will not be easy. Research by Csiszar and

colleagues has dealt with attempting to find viable enzymatic approaches
to removing seed coat fragments in order to create a total enzymatic
approach to the scouring of cotton fabric. They demonstrated that cellulases
could be used to clip fibers from the fragments, enhancing their tendency

to fall off, and that the cellulases could also help to open up the fragments
to further chemical attack (Csiszar et al., 1998a, 1998b). Further work dem-
onstrated that if a chelating agent such as EDTA is added to hemicellulase
and xylanase enzymes, then the seed coat fragments are hydrolyzed much
faster than the cotton fabric itself. In addition, it was shown that the removal
of the calcium ions enhanced the removal of colored impurities in the alka-
line process (Csiszar et al., 2001a; Losonczi et al., 2005).
Additional research for enzymatic approaches to seed coat fragment
removal involved the investigation of the degradation of the lignins in seed
coat fragments by xylanase (Csiszar et al., 2006). Tavcer concluded that for

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