Test for starch
Brittney Humphries.
Title:
Testing for the Presence of Starches, and Proteins
Purpose:
To test for the presence of starches and protein macromolecules, to introduce the concept of variations in chemical compounds.
Hypothesis:
If biuret is blue after a test for protein, then it is a negative result because biuret reagent is blue to begin with. If a solution is pinkish purple, or purple, then the test for protein is positive. The test solution for starches is yellowish brown. If any substance that is yellowish brown when mixed with iodine, then the test for starches is negative. If the solution turns purple, or a dark purplish black, then the test for starches is positive. If DI water, and sucrose are tested for proteins using biuret reagent, then they will show a negative result. To explain, both DI water, and sucrose alone do not contain a trace of protein. In addition, deionized water is commonly used in experiments as a negative control. In both experiments, if the DI water is tested for a protein or starch, then it will come back as a negative. If milk solution, and 50% egg white solution are tested for proteins using the biuret solution, then there will be positive results because both of these are composed of protein macromolecules. The use of condensed milk brings about an even stronger positive result for protein than regular refrigerated milk, since condensed milk is higher in protein. If DI water, onion juice, and sucrose are tested for starches using iodine, then there will be a negative result for starches. This is because there are not any traces of starch in these solutions. On the other hand, if 1% starch solution is tested for starch using iodine, then there will be a positive result for starch since there is starch present.
Materials and Methods:
Test Tube Rack
4-5 Test Tubes
Transfer Pipet
Protective goggles
Deionized Water (DI water)
Evaporated Milk
50% Egg White Solution
1% Sucrose Solution
1% Starch
Onion juice
Sucrose
Title:
Testing for the Presence of Starches, and Proteins
Purpose:
To test for the presence of starches and protein macromolecules, to introduce the concept of variations in chemical compounds.
Hypothesis:
If biuret is blue after a test for protein, then it is a negative result because biuret reagent is blue to begin with. If a solution is pinkish purple, or purple, then the test for protein is positive. The test solution for starches is yellowish brown. If any substance that is yellowish brown when mixed with iodine, then the test for starches is negative. If the solution turns purple, or a dark purplish black, then the test for starches is positive. If DI water, and sucrose are tested for proteins using biuret reagent, then they will show a negative result. To explain, both DI water, and sucrose alone do not contain a trace of protein. In addition, deionized water is commonly used in experiments as a negative control. In both experiments, if the DI water is tested for a protein or starch, then it will come back as a negative. If milk solution, and 50% egg white solution are tested for proteins using the biuret solution, then there will be positive results because both of these are composed of protein macromolecules. The use of condensed milk brings about an even stronger positive result for protein than regular refrigerated milk, since condensed milk is higher in protein. If DI water, onion juice, and sucrose are tested for starches using iodine, then there will be a negative result for starches. This is because there are not any traces of starch in these solutions. On the other hand, if 1% starch solution is tested for starch using iodine, then there will be a positive result for starch since there is starch present.
Materials and Methods:
Test Tube Rack
4-5 Test Tubes
Transfer Pipet
Protective goggles
Deionized Water (DI water)
Evaporated Milk
50% Egg White Solution
1% Sucrose Solution
1% Starch
Onion juice
Sucrose