Abstract The objective of the Reducing Sugar Test was to test if the substance has a reducing sugar in it by adding Benedict’s solution and heating it, there would be a color change if a reducing sugar is present, or it will remain blue (no reducing sugar). The objective of the Starch test was to test for starch in substances by using Iodine. The iodine will cause a substance to turn to a dark blue color if it is positive for starch. The objective for the Grease Spot Test was to test if the substance had a lipid.
A positive reaction would make a translucent grease mark on a brown paper bag. The objective for the Dye test was to test for lipids. When mixed with water and the tested substance, a positive result will occur in it being separated from the water. The objective of the Protein Test was to test for proteins present in a substance using the Biuret Solution. The substance should produce a violet color within 10 drops of Biuret. The objectives of the Spit Lab were to test for starch, a reducing sugar, and effect of amylase on a cracker that is positive for starch and negative for a reducing sugar.
Iodine would test if starch was present if the cracker solution changes to a dark black/blue color. Benedict’s Solution mixed with the cracker and heated would test for a reducing sugar (if reducing sugar, it will turn from a green to an orange to a dark brownish color). The amylase was tested on a Triscuit cracker by heating it in Benedict’s Solution, the amount would make it either a green, or orange, and the most amounts would make it brown as mine and my partner’s results. 1. Introduction The chemical aspects lab was done to detect and identify the presence of reducing sugars, starches, lipids, and proteins in various substances.
A reducing sugar is a monosaccharide or disaccharide that has the ability of giving electrons to other molecules and acts as reducing agent. A reducing agent has an aldehyde or ketone group in it that can reduce the ions of some metals, such as sodium citrate, copper sulfate, sodium bicarbonate (Benedict’s solution). In order to be a reducing sugar, the sugar must have a beta-beta bond, which is the bond that can be broken by heat. If they have an alpha-beta bond, like sucrose, then the test material does not have reducing sugars present, it will remain blue.
If there are reducing sugars present in the substance, the color will change from a green to orange to dark brown state. Starch is a carbohydrate that is found in potatoes and other grains. It is made of a large number of units of glucose. When starch is consumed, the body’s enzymes break it down into glucose, a monosaccharide. Starch can be identified in a test material by adding drops of iodine to it. The iodine should go into the polysaccharide chain, so the color changes to a black color, or precipitate will form. A lipid is a hydrophobic polymer made of two monomers.
Since they are hydrophobic it differentiates lipids into a separate group of polymers. The monomers that make up lipids are glycerol and three fatty acids. Lipids store energy and are in hormones. There are two ways to be able to detect a lipid in a test material, a grease spot test or a dye test. The grease spot test is used to test for only lipids that are highly concentrated. Lipids are known to be translucent when on paper. So you add a drop of the substance onto a brown sheet of paper and add a drop of water next to it then let them evaporate.
After observing the drops through light by holding it up and trying to look through the paper, if it is translucent, it is a lipid. A more accurate test for lipids is the dye test. If water is combined with Sudan III (Sudan IV was replaced by this), and mixed with the test material, the test material can be considered a lipid if the solution forms a pink color. This is because Sudan III (Sudan IV was replaced by this) is only soluble in lipids. The lipid will be distributed on top of the dyed water, because lipids are hydrophobic. A protein is a polymer made of amino acid monomers.
The amino acids bond together in bonds called peptide bonds. A chain of amino acids is called a polypeptide chain. The structure in which the amino acids are bonded determines the function of the protein. There are about twenty different amino acids, but there is a wide variety of possible combinations that amino acids can bond, therefore proteins have quite a lot of functions. Some things proteins are used for are the building of the muscles, tendons, organs, glands, nails, and hair. There are many more different functions for proteins.
To detect proteins in test materials, there is an identifying agent called Biuret Solution which when mixed with the test material. It turns purple if it contains a protein. The darker the violet color, the more concentrated it is with protein. The spit lab was done in order to determine the effect of amylase on starch since starch is a long chain of glucose which serves as a main source of nutrients; the amylase breaks it into a simple monosaccharide. Amylase is an enzyme in the human saliva used to break starch into reducing sugars for energy. An enzyme is a protein, and enzymes speed chemical reactions.
Benedict’s Solution was mixed with chewed up Triscuit (which was positive for starch only before), and heated for 2 minutes. This was done in order to create a reaction between the enzymes and starches in the cracker. The darker the color, the more amylase your body had at that time, if it does change color. 3. Experimental Section/Procedure Changes: – In the protein test, a cracker solution was used as opposed to cereal. – Sudan IV was replaced by Sudan III – In the lipid test, a cracker solution replaced buttermilk Procedure: (See attached lab sheet) 4. Data Section
Test Material| Starch| Result| Reducing Sugar | Result| Lipid Grease| Result| Lipid Dye| Result| Protein| Result| 1% Starch| Black| +| Blue| -| Not Tested| N/A| Not Tested| N/A| Clear| -| Potato Juice| Black| +| Not tested| N/A| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| Water| none| -| Blue| -| Not translucent| -| No pink| -| Clear| -| Milk| none| -| Orange| +| Not Translucent| -| Pink| +| Not Tested| N/A| Cracker Solution| Black| +| Not tested| N/A| Not Translucent| -| Pink| +| Clear| -| Cereal| Precipitate| +| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| 5% Glucose| Not tested| N/A| Orange| +| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| 5% Fructose| Not Tested| N/A| Orange| +| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| 5% Sucrose| Not Tested| N/A| Blue| -| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| 5% Lactose| Not Tested| N/A| Orange| +| Not Tested| N/A| Not Tested| N/A| Not Tested| N/A| Egg Albumin| Not Tested| N/A| Not tested| N/A| Not Tested| N/A| Not Tested| N/A| 2 drops violet| +| Gelatin| Not Tested| N/A| Not tested| N/A| Not Tested| N/A| Not Tested| N/A| 3 dropsviolet| +| Salad Oil| Not Tested| N/A| Not tested| N/A| Translucent| +| Pink| +| Not Tested| N/A| Spit Lab Cracker| Starch Test| Result| Reducing Sugar test before amylase| Result| Reducing Sugar test after amylase| Result| Triscuit| Black| -| Blue| -| Brown| +| Saltine| Black| +| Orange| +| Not Tested| N/A| 5. Analysis
The labs were done to test for starch, lipids, proteins, and reducing sugars. The test for starch was done by adding up to 3 drops of iodine into the substance which should be on the porcelain spot plate. The result of a positive starch reaction would be a dark blue/ black color and/or precipitate formed. The substances that had starch were: cracker solution, Triscuit cracker, cereal, saltine cracker, potato juice and 1%starch. These results were expected because of the type of food involved. There were two lipid tests done. The first one was the Grease Spot test, where a drop of the substance and water were placed on a piece of brown paper bag.
After it evaporated, and if the brown paper became translucent then it meant that it was a highly concentrated lipid. The only material that showed this was salad oil and it was expected due to the fact that it’s an oil, milk was also expected but did not show up. The second test was the Dye test with Sudan III. Due to the properties of Sudan III, making it only soluble in lipids, it is added to 3ml of water and 1ml of each test material, and then shaken. There was a color change; it changed to pink so the lipid absorbed it causing it to change. Positive substances included: Salad oil, milk, and crackers. The expected ones were salad oil and milk, but the crackers weren’t expected.
The Reducing Sugar test was done by placing 5ml of Benedict’s solution into a test tube then adding 10 drops of the test substance, and then heated for 2minutes. If the substance was positive for a reducing sugar, the color would vary from green to orange to dark brown, the beta-beta bond is broken and the color change shows this. The substances that showed positive were: 5% glucose, 5% fructose, 5% lactose, milk, and Saltine crackers, Triscuit crackers (after amylase). The spit lab showed how starch before amylase was negative for a reducing sugar and then after the amylase was added, the alpha-beta bond broke. These were all expected except the saltine cracker that had a reducing sugar.
The Protein Test was done by taking 5ml of the test material and putting it in a test tube, then adding 1 drop of Biuret solution up to 10 times to see if a violet color appears. The Biuret solution (made of potassium hydroxide and hydrated copper (II) sulfate) reacts to peptide bonds. Amino acids are monomers of protein and amino acids are linked to peptide bonds so they will react to the Biuret. The substances that were positive for protein were only egg albumin and gelatin. Egg albumin was expected, but gelatin wasn’t. Possible Errors -Cross contamination between substances through pipettes, test tubes. – Misread/misinterpreted data results. -Possibly followed procedure wrong. – Wrong measurements of substances. 6. Conclusion Starch Test 1. The positive control was 1% starch. 2. The negative control was water. 3.
If there was a color change (black or dark blue), or precipitate formed, starch was present when iodine was added. 4. The 1% starch showed the most amount of starch because it hard a really dark shade of blue and because it is starch. 5. The material that showed the least amount of starch was the cracker solution because it had a lighter shade of blue when iodine was added. Reducing Sugar Test 1. The positive control was both fructose and glucose because they are both reducing sugars. 2. The negative control was water. 3. A reducing sugar was present in the test material if it had a color change from green to orange to dark brown after being heated for 2 minutes. 4.
The materials that had reducing sugars present were: 5% glucose, 5% fructose, 5% lactose, and milk. 5. The materials that tested negative for reducing sugars were: 1% starch, water, and 5% sucrose. 6. The materials that showed positive for reducing sugars all had beta-beta bonds. 7. The materials that showed negative for reducing sugars all had alpha-beta bonds. (Water has only hydrogen bonds not beta-beta or alpha-beta. ) 8. The purpose of heat is to be the energy source to break the beta-beta bonds. 9. If there was no heat, the milk, lactose, sucrose, wouldn’t break. The beta-beta bonds would remain intact since there isn’t an energy source. 10.
Enzymes are proteins that speed up chemical reactions. Their purpose is to help break things down. For example, the enzyme amylase is in the saliva of a human and helps break starch (polysaccharide) down into Glucose, a monosaccharide. Lipid Test 1. The positive control is salad oil. 2. The negative control is water. 3. The two ways to observe the presence of a lipid are to put a drop of the material onto brown paper and see if it leaves a translucent grease mark, or add Sudan III to the material with water, and then shake it all up in a test tube to see if a pink color will show. Protein Test 1. The positive control is the egg albumin. 2. The negative control is water. 3.
The amount of protein in the test material can be estimated through the number of drops the Biuret Solution took; the less drops the more protein. Spit Lab 1. The starch test was done in order to see if the crackers had starch, or else amylase wouldn’t do anything to it. 2. The Saltine and Triscuit crackers showed positive for the starch test. 3. The purpose of the reducing sugar test was so that if the cracker did have a reducing sugar, the heat could have broken the bond, not the amylase. The cracker had to not have a reducing sugar so we know it was the amylase breaking the starch alpha-beta bond. 4. I chewed the Triscuit cracker because it was a starch and it wasn’t a reducing sugar, perfect for the amylase test. 5.
The reaction changed after I chewed the cracker and did the reducing sugar test. The alpha-beta bond broke due to the amylase and it turned dark brown, before it wouldn’t break and stayed blue. 6. The amount of amylase can be estimated but the color of the solution after the reducing sugar test. For example, green means little, orange means medium, and dark brown means there is a plethora. 7. I liked how we got to test how much amylase we had at the given moment. 8. If I were to do this lab again, I really wouldn’t change anything, the procedure is simple as it could be. The chewing the cracker part wasn’t fun, but it was necessary for your own result.