The efficiency of an enzyme treatment in reducing wool shrinkage

Abstract

The influence of different experimental conditions, chosen according to a central rotatable plan (Box-Hunter) at three levels of treatment time, on the shrink-resistance properties of wool treated with serine proteinase Bactosol SI is investigated. The independent variables in the central rotatable design were the concentration of Bactosol SI and the pH value of the treatment bath. The percentage area shrinkage, degree of whiteness, loss of weight, and ball-penetration-resistance loss were the responses. The results showed that the enzyme concentration and the pH value of the treatment bath had a large influence on reducing the wool shrinkage and on the degree of whiteness. The treatment time also had a marked influence, mainly on changes to the mechanical characteristics of the knitted wool fabric as expressed by the loss of weight and the ball-penetration-resistance loss. An optimization diagram at a treatment time of 90 minutes and with the optimal experimental conditions of an enzyme concentration of between 4.8 and 7.2 g/L and pH values of between 8.6 and 9.75, for particular combinations, or of between 5.4 and 6.8 g/L of enzyme and pH values of between 8.75 and 9.40 for any combination, is presented. Finally, the effects obtained after enzymatic treatment were compared with the results for a Basolan DC-treated sample.