Lipid distribution on textiles in relation to washing with lipases

Effectiveness of lipase in detergency was studied using three test soils (l ard, artificial sebum, and olive oil) on a woven cotton fabric. Distributio n of oily soil on fabrics was determined for three different treatments (un washed, washed with detergent without lipase, and washed with detergent pil ls lipase). Osmium tetroxide was used to label lipid soil for analysis in t he scanning electron microscope. Both longitudinal and cross-sectional back scattered electron images for unwashed samples showed that soil was present on surfaces of the cotton fibers and in interfiber spaces of the yarn bund le. Lard soiled samples had large deposits on the fabric surfaces, while ar tificial sebum and olive oil appeared more uniformly distributed throughout the textile. Oil was deposited in the interfiber capillaries of the yarn b undle and in the crenulation, secondary walls, and lumen of the fibers. Ene rgy dispersive X-ray microanalysis was used to determine relative concentra tions of oil at selected morphological locations within the fiber structure and at the fiber surface. Soil distributions within the fibrous structures differed with type of soil and laundry treatment. Backscattered electron i mages dramatically demonstrated the effect of lipase on cleaning. After was hing with detergent plus lipase, yarn surfaces had much less residual soil; residual soil that remained was in the irregularities of the cotton fiber surfaces. Concentrations of oil in the secondary walls, crenulations, lumen , and the fiber surfaces were lower after lipase treatment for all three so ils. While washing with detergent removed soil from the yarn and fiber surf aces and the crenulation of the cotton fiber, only the samples washed with detergent plus lipase had lower concentrations of soils within the secondar y wall and lumen of the cotton fibers. Fabrics soiled with olive oil and wa shed with detergent plus lipase had the lowest concentrations of residual s oil across the textile structure; the residual soil observed was mainly in the irregularities on the fiber surfaces.