Function of lipase in lipid soil removal as studied using fabrics with different chemical accessibility

Fatty stain removal is enhanced by the inclusion of lipase in washing compo unds and leads to increased lipid removal from within the fibers. Cotton fa brics with varied morphology/chemistry were investigated to study the acces sibility of soil in textiles to detergent and lipase. Three cotton fabrics (untreated, mercerized, and carboxymethylated cotton), differing in chemica l accessibility, and Tencel(TM) lyocell fabric, a microdenier manufactured cellulosic fiber, were subjected to three treatments-unwashed, washed with detergent, and washed with lipase-so as to understand further the effects o f fiber morphology on lipase effectiveness. Both detergents and lipase remo ved more soil from the more chemically accessible and hydrophilic textiles. Lipase increased lipid removal for all fabrics and all morphological locat ions on the fiber, including fiber surfaces, interfiber capillaries, small capillaries, and the center of the yarn bundle. Lipase removed significant quantities of soil from the lumen in untreated and mercerized cottons; thes e fabrics showed the largest total increases in amount of lipid removed by lipase. When the fiber surfaces were smoother and the fiber structure was l ess open and not carboxymethylated, i.e., the mercerized cotton fabric, mor e lipase benefit was observed (72% of the residual soil left after washing with detergent was removed when lipase was added). The total soil removal f rom the mercerized cotton fabric by use of lipase was equal to that observe d for the more open, hydrophilic carboxymethylated fabric and for the Tence l, which has no lumen or other morphological features of natural cotton suc h as crenulations. Lipase appeared to enhance lipid removal under condition s where removal by the detergent surfactant system was limited. Furthermore , we concluded that lipase acted to remove lipid soil from within the fiber s by functioning at the interior surfaces of microfibrils and pores within the fiber structure at the lipid-water interface.