Page 80 - Advances in Textile Biotechnology

Smart materials containing enzymes or enzyme substrates 59

fabrics was demonstrated against Staphylococcus aureus and 43% of the

activity was retained after five cycles of use (Wang et al., 2009).
3.2.3 Functional packaging materials
For applications in the food industry, lysozyme (registered as a food addi-

tive) was incorporated into chitosan films. Controlled release of the enzyme
led to 3.8 log cycles reduction in S. faecalis and 2.7 log cycles reduction in
E. coli (Park et al., 2004). Besides lysozyme, oxygen-consuming enzymes
were immobilized in food-packaging materials to prevent microbial growth.
Immobilization of glucose oxidase and alcohol oxidase on polypropylene
(PP) and polyethylene (PE) has been demonstrated to improve the shelf-
life of food products by preventing growth of moulds, yeasts and aeraobic
bacteria (Labuza and Breene, 1989, Vermeiren et al., 1999).
Apart from antimicrobial properties, enzymes have been incorporated

into packaging materials to control off-flavours. Naringinase, composed of
α-rhamnosidase and β-glucosidase was incorporated into cellulose acetate

(CA) in order to reduce the bitter flavour in grapefruit juice by hydrolysis
of naringin to naringenin and pruning (Soares and Hotchkiss, 1998).

3.2.4 Enzyme immobilization on fabrics
Fabrics are increasingly gaining importance as supports for enzyme immo-
bilization (Table 3.1) and thus only selected examples will be discussed in
the following.
Horseradish peroxidase (HRP, EC 1.11.1.7) immobilized on non-woven
polyester fabrics in the presence of glutaraldehyde as a crosslinking agent
retained 85% of its activity after 4 weeks of storage at 4 °C compared with
90% activity loss of the free enzyme under the same conditions (Mohamed
et al., 2008). HRP can be used for the production of electrically conductive

polyaniline having a well defined thickness. Therefore, HRP was covalently
immobilized on radio-frequency (RF) plasma-activated polyethylene and
the synthesis of polyaniline was demonstrated (Alvarez et al., 2003).
Catalase (EC 1.11.1.6) is widely used in applications ranging from
textile bleaching and electronics to sterilization of liquid food products for
conversion of residual hydrogen peroxide to oxygen and water. Apart from
various inorganic carrier materials (Costa et al., 2001, Gudelj et al., 2001),
fabrics have been used for catalase immobilization. Catalase was photo-
chemically immobilized on polyester (PET) and polyamide 6.6 using dial-
lylphthalate or cyclohexane-1,4-dimethanoldivinylether as cross-linking
agents. The immobilized enzyme was highly stable with a 3.5 higher activity
after 20 cycles when compared with the free enzyme (Opwis et al., 2004,
2005). Another strategy for catalase immobilization on cotton fabric was
based on oxidation of cotton by sodium periodate followed by covalent
attachment of the enzyme (Wang et al., 2008).

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