Food Testing Lab: Organic Compounds
PURPOSE
Organic compounds are found in all living things, including the foods that we eat. In this lab
you will perform several chemical tests on different solutions to determine the presence of
various organic molecules. By using simple laboratory tests, you can determine if certain
foods contain carbohydrates, proteins, and fats.
PRE-LAB
Make a cartoon of each of the laboratory procedures below. It is very important that you
understand the steps of this lab so that we do not contaminate our samples and so we stay
safe.
PROCEDURE
Protein Test
1. Put 20 drops of protein solution into a clean test tube.
2. Add 5-10 drops of Biuret solution.
3. If your solution turns purple, there IS protein present.
4. Repeat this test with a test tube filled with 20 drops of water + Biuret solution. This
is your “negative control.” The tube should NOT turn purple.
Sugar Test
1. Put 20 drops of Benedicts solution into a test tube.
2. Add 5-10 drops of Sugar solution.
3. Hold the test tube (with a test tube holder) in the hot water bath for 2-3 minutes.
4. If the solution turns brown-orange, it means that there is a SUGAR present.
5. Repeat this test with a test tube filled with 20 drops of water + Benedicts solution.
This is your “negative control.” The tube should NOT turn brown-orange.
Starch Test
1. Put 20 drops of starch solution into a clean test tube.
2. Add 5-10 drops of iodine solution.
3. If your solution turns blue or black, there IS starch present.
4. Repeat this test with a test tube filled with 20 drops of water + Iodine solution.
This is your “negative control.” The tube should NOT turn blue or black.
Lipid Test
1. Place 1-2 drops of oil or other test solution on the brown paper.
2. Pick up the paper and see if you can partially see through the paper. If you can,
LIPIDS / FATS ARE present.
3. Repeat with water. You should NOT be able to see through the paper.
Food Testing Lab, Continued
1. Record your data in the table.
2. Lastly, test your unknown “mystery” solution given to you by your teacher. ONLY
ADD INDICATOR SOLUTION to your mystery tube.
3. Clean your test tubes with soap and water and the test tube scrub brush! You will not
be excused until all stations are clean!
Organic
Compound
Test
Description of
Color when
the Compound
is Tested
Is the Organic
Compound
Present?
Yes or No
Description of
Color when
Water is tested
Is the Organic
Compound
Present?
Yes or No
Protein
Starch
Sugar
Lipid
MYSTERY SOLUTION
Organic Compound Test
Describe color change
Is the organic compound
present?
Yes or No
Protein
(add indicator Biuret)
Starch
(add indicator Iodine)
Sugar
(add indicator Benedicts
and boil)
Lipid
(test on brown paper)
What foods found in your regular diet contain the same compounds as your mystery
solution?