Mechanism of enzymatic scouring on cotton fabric using pectinase, protease, lipase and cellulase

Abstract

This research revealed the mechanism of enzymatic scouring of cotton fabric using 4 commercial enzymes: pectinase, lipase, protease, and cellulase. The mechanism was established based on results from the analyses of the hydrolyzed products and the scoured fabrics after scouring using a one-step process with pectinase and a two-step process with either lipase then cellulase, protease then cellulase, or lipase/protease then cellulase. Three analytical techniques consisting of UV-Vis spectrophotometry, HPLC and GC were used to determine the amounts of reducing sugars, galacturonic acid, amino acids, and fatty acids from the hydrolyses of cellulose, pectins, proteins, and waxes/fats respectively, and other tests were performed on scoured fabrics. UV-Vis spectrophotometric analysis indicated that the pectinase scouring process produced approximately 18 fold higher amounts of reducing sugars and galacturonic acid than any of the two-step scouring processes. The production rate of reducing sugars and galacturonic acid from most of the scouring processes showed a decrease with an increase in time in a quadratic relationship. The kinetic study of these two hydrolyzed products suggested that Ghose-Walseth kinetic system could be used to explain the production of reducing sugars and galacturonic acid from these enzymatic scouring processes. HPLC analysis revealed that the lipase/protease/cellulase scouring processes produced approximately 5 fold higher amounts of 17 amino acids than the pectinase scouring process. GC analysis for 18 fatty acids (C[subscript 8]–C[subscript 24]) revealed that three major fatty acids; palmitic acid, stearic acid, and behenic acid were found on both the scoured and the unscoured fabrics. Scoured fabrics were tested for content of proteins, extractable components, waxes, and anionic components including pectins and some differences among the fabric scoured with different enzyme combinations were found. After all scouring processes, fabrics showed adequate water absorbency because only a residual content of waxes was left. All enzymatic scouring processes did not affect the bulk property of the fabric such as the physical strength and the crystalline. All enzymes could be effectively used to scour cotton either alone or in combination. Although these enzymes showed various actions on cotton impurities, they all performed effective scouring. It was found that pectinase and cellulase could hydrolyze both pectins and cellulose directly, protease could act on them indirectly through the protein hydrolysis while lipase did not act on them at all. All four enzymes could act either directly or indirectly on proteins and waxes/fats.