Direct scouring of greige cotton fabrics with proteases

Our previous work demonstrated that proteases are effective scouring agents for boiling-water pretreated cotton fabrics. In this study, we investigate whether proteases are effective scouring agents when directly applied on r aw greige cotton fabrics without the boiling water pretreatment. Direct rea ctions with three proteases, i.e., trypsin, chymotrypsin, and subtilisin, o n greige cotton fabrics show that all three improve fabric wettability to a level similar to alkaline scouring under mild conditions (45-55 degreesC, pH 7). The reaction conditions required to achieve optimal fabric wettabili ty (cos theta > 0.6) are 5 g/L and 45 degreesC for trypsin and 5 ml/L at 55 degreesC for subtilisin. Chymotrypsin is effective under several reaction conditions, i.e., 1 g/L at 55 degreesC, 2 g/L, at 45 degreesC, and 5 g/L at 35 degreesC. Most reactions take 30 minutes, and room-temperature water ri nses replace the post-reaction buffer rinses. Compared to protease scouring of boiling-water pretreated cotton, direct protease scouring of greige cot ton fabrics requires increased concentration (subtilisin), higher temperatu re (subtilisin and chymotrypsin), or longer time (trypsin and chymotrypsin) to achieve similar water wettability and absorption properties. The most d istinct outcome of direct protease scouring of greige cotton fabrics, in co mparison to boiling-water pretreated and protease scoured and alkaline scou red cotton, are the resulting fabric characteristics, i.e., less lateral sh rinkage, no change in surface friction, easier to shear, and more resilient to compression and bending.