**5.6 Bio-polishing**

The process of removal of micro, fuzzy fibrils from the fabric surfaces through the action of cellulase enzyme is called bio polishing. It enhances the color brightness, hand feel, water absorbance property of fibers; strongly reduce the tendency for pill formation [123]. Cellulase enzymes are widely used for bio polishing.

Cellulases enzymes hydrolyze the cellulose structure by degrading β-(1-4) glycosidic linkages. Endocellulases cleave bonds along the length of cellulose chains in the middle of the amorphous region, exoglucanases act from the crystalline ends of cellulose chains and convert soluble oligosaccharides to glucose. Commercially available cellulases enzyme for bio polishing are a mixture of endogluconases, exoglucanases & cellobioses (**Table 14**).

Bio polishing is done before or after dyeing to the cotton, fabrics influence dyeability, besides improving the appearance and handle properties. Cellulase enzyme treatment enhances the post dyeing effect and resin finishing with increases softness. Endoglucanases with acid cellulase are suited for bio polishing of cellulosic fabrics [124]. The enzymatic hydrolysis of cotton also enhanced by mechanical action with the addition of surfactant. For bio polishing acid and neutral cellulases bath is maintained at 4.5–5.5 and 7 respectively, the process is heated at 55<sup>o</sup> C. Finally, the process is terminated at the temperature 85<sup>o</sup> C. The immobilization of cellulase can restrict its action to fiber surface. Various immobilization of cellulases enzyme methods improve thermal stability and reusability [125].
