Determining the Effects of Age of Stain on Stain Removal Annabel Winterberg, Skye Murray October 3rd 2014 Introduction The purpose of this experiment was to determine the effect of the age of a stain on how effectively laundry detergent removes it. It is expected that the longer a stain goes without laundering, the harder it will be to remove. This is because the stain has had longer to attach itself to the fabric, and because it has become dehydrated (1). Clothing stains are formed when substances are molecularly attached to fibers in the fabric (2). The longer the stain goes without washing, the more time it has to react with and set in the clothing (3). When substances first react with the fibers in the fabric, they have moisture, and are able to react well with the detergents when they are placed in the wash. But as stains are left out longer, they begin to lose water, and are less reactive to the chemicals in laundry detergent. The longer stains remain unwashed, the more dehydrated they become (1). After about two months stains because almost untreatable (3). Stains need water because that is what laundry detergent uses to remove them. Laundry detergent also removes stains with several enzymes (4). Enzymes are proteins found in living things, whose primary goals are to speed up chemical reaction (5). They do this because of a small area on their tertiary structure called the active site. The active site is the same shape as a certain molecule, called the substrate. Substrates fit into the active site, and this lowers the activation energy needed to start a chemical reaction (5). The substrate then either synthesizes with another substrate to form a molecule, or decomposes into two separate molecules (5).
Enzymes play an important part in digestion. Humans eat food to obtain the nutrients needed for energy and cellular work (5). However, the food is too large for the cells to use (5). Thus digestion breaks down polymers into monomers. Enzymes help digestion by decomposing these nutrients (5). Proteins are digested in the stomach with the enzyme pepsin, and in the small intestine with the enzyme trypsin. These enzymes that digest proteins are called proteases (5). The end products of this digestion are monosaccharides, amino acids, and fatty acids and glycerol. These molecules can then be introduced into cells and used for energy or to make new complex molecules (5). These proteases used for digestion are what laundry detergents contain to remove stains (4). These enzymes remove stains the same way they do in digestion, the enzyme fits with the substrate in the stain, and breaks it down to simpler molecules. Afterwards, other ingredients in the laundry detergent remove the smaller molecules (4). The stains tested in this experiment, are from Poa pratensis or Kentucky Bluegrass. This is the type of grass is commonly used through the United States (6). Grass leaves a stain because of its green color, which is due to a pigment called chlorophyll. Chlorophyll is a protein, meaning it needs to be removed by a protease enzyme (7&8). The detergent used by this lab is Tide, which contains proteases that digest chlorophyll proteins (4). This experiment s findings will be important because it can reduce textile and environmental waste. In 2012 14.3 million tons of textile waste were generated. This waste often goes into landfills or incinerators (9). Only an estimated 14.4% of textiles were recovered for reuse (9). A major reason clothing cannot be recovered for reuse is because it has become mildewed or stained (9). If this lab shows that age of stain is a factor in stain removal, people can
be informed to wash stained clothes quickly. Then more clothes will be available for reuse, reducing the amount of clothing going into incinerators and landfills. Methods To determine if age of stain affects stain removal, a piece of thin white fabric was first cut into a 6 by 6 inch square. It was was labeled 1 with a Sharpie in the top left corner. The fabric was then taken outside and vigorously kneaded into a patch of Kentucky Bluegrass, until a suitable grass stain was formed. Observations were then made about the diameter of the stain, and vividness of its colors. The fabric was kept on a table in a bedroom where it could not be tampered with. Two days later another 6 by 6 inch piece of white fabric was cut, and labeled 2. The fabric was rubbed in the same patch of kentucky bluegrass, and observations were recorded about its diameter and vividness of colors. Using an i Pad Mini, pictures were then taken of the first and second stains. Two partially opaque plastic jars with scientific measurements along the sides and a 500mL of total volume were placed under a sink and filled with cool water. When the water reached the 250 ml line they were removed from the sink. One jar was labeled Recent with a Sharpie, the other jar was labeled Older. A container of Tide Liquid Laundry Detergent was opened, and a small amount was poured into its cap. A 1 ml pipette was attached into a fast release pipette pump, and 5 ml of laundry detergent entered into the pipette. The pipette pump then released the detergent into Older Jar The same process was repeated for the Recent Jar Fabric 1 was folded up and placed into Older Jar. The cap was tightly put onto the jar, and the jar was shook forcefully for 5 minutes. Fabric 2 was placed into the Recent Jar, and shook for 5 minutes. This was done to simulate a washing machine. Older Jar was brought to a
sink, its cap was removed and its contents were emptied into the sink. Fabric 1 was retrieved from inside the jar, and rinsed off with water from the sink for 30 seconds. It was placed under a paper towel and dried for 3 minutes. The procedure was repeated with Recent Jar. After the fabrics had dried slightly, new observations about the diameter and vividness of the colors were taken. Pictures were also taken using an i Pad Mini. Discussion These results agreed with the hypothesis, that the longer a stain goes with laundering, the harder it will be to remove. Stain 1, which had been untreated for 2 days, was virtually unchanged in size and color. Stain 2, which had been formed immediately before the experiment, had shrunk and was harder to see. This means that stains must be washed immediately, if they are to be removed. The reason the enzymes were not able to remove Stain 1 was because it had bonded with the fabric, and because it had become dehydrated. In the two days between when Stain 1 was formed and when it was laundered, it had time to bind tightly to the fabric fibers. This means the enzymes could not digest the chlorophyll molecules because the substrates were already bound to something else. Stain 1 also had become dehydrated in the two days before it was washed. When it was first formed, the stain had water from the broken cells on the fabric, but eventually these evaporated, leaving the stain dried out with no water. This was problematic for the enzymes, because water is needed for the hydrolysis of proteins. Hydrolysis uses water to break down molecules (5). Because of the lack of water on the stain, the enzymes were unable to catalyze and the molecules remained as they were. Stain 2 had none of these problems. Stain 2 was laundered minutes after it was formed, so its chlorophyll molecules had little time to tightly bond to the fabric, and it still had much water
between its molecules. Thus the enzymes had a much easier time decomposing the chlorophyll, and shrinking the stain. However, the stain was not completely removed. This could be because grass stains are very hard to remove (10). Grass stains are naturally compatible with many types of fabrics, and often contain dirt (10). Dirt can be a combination of lipids, carbohydrates, and proteins, meaning it needs multiple enzymes to remove (11). The proteins in chlorophyll also make dirt attach more strongly to fabric (10). The Recent Stain seemed to have a high concentration of dirt. Future experiments should test how the age of different types of stains affects them. This experiment used only one type of stain, grass, which contained mostly proteins. Another experiment might test a variety of stains from different organic compounds, such as mayonnaise, whose stain would be a lipid, or ketchup, whose stain comes from the protein lycopene as opposed to chlorophyll. Labs might also test more variables for age of stain, instead of just two. Stains can be obtained as follows: one month, two weeks, one week, five days, two days, one day, one hour, and five minutes before. This would provide even more data about age of stain and narrow down when stains are too old to be properly removed. References 1. Duinhoven, Susan. Enzyme Adsorption at Solid liquid Interfaces. Vlaardingen: Unilever Research Laboratory, 1992. Enzyme Adsorption at Solid liquid Interfaces. Unilever Research Laboratory. Web. 5 Oct. 2014. 2. Price, Judy L., and Anne T. Lemley. Removing Stains at Home. Ithaca: Cornell Cooperative Extension, 2003. Web. 5 Oct. 2014 3. Stain Removal. Museum Conservation Institute Stain Removal. Smithsonian Museum
Conservation Institute, 2008. Web. 05 Oct. 2014 4. Enzymes in Laundry Detergents. Enzymes (proteases, Lipases, Amylases) in Laundry Detergents. Procter & Gamble, n.d. Web. 04 Oct. 2014. 5. Energy, Life, and the Biosphere. BSCS Biology. a Molecular Approach. New York: Glencoe/McGraw Hill, 2006. N. pag. Print 6. Turfgrass Kentucky Bluegrass. Kentucky Bluegrass Identification & Common Problems. Scott's Lawn Service, n.d. Web. 05 Oct. 2014. 7. May, Paul. "Chlorophyll." Chlorophyll. University of Bristol, May 2000. Web. 05 Oct. 2014. 8. Carter, J. Stein. "Photosynthesis." Photosynthesis. Clermont College, 15 Aug. 2000. Web. 05 Oct. 2014. 9. Textiles, Common Wastes & Materials. EPA. Environmental Protection Agency, n.d. Web. 05 Oct. 2014 10. Wilson, Cornia. "How to Remove Grass Stains."16 July 2009. Web. 07 Oct. 2014 11. Chaplin, Martin. "The use of enzymes in detergents." The use of enzymes in detergents. London South Bank University, n.d. Web. 6 Oct. 2014