Identification of Proteins and Lipids in Food Samples

Objective: To analyze food samples for the presence of lipids, carbohydrates and proteins.



Part A:

1. Place 1 drop of oil on a piece of paper bag. Allow to sit for 5 minutes

2. Place 1 drop of water on a paper bag. Allow to sit for 10 minutes

3. Observe the paper bag for any changes. The oil is your positive control and the water is your negative control.

4. Draw 4 circles on your paper bag and label as follows:

5. Place a piece of each sample on the paper bag and allow to sit for 5 minutes. Remove samples and analyze bag for presence of lipids. Record data below.

Table 1-2 Test for Lipids

Positive or Negative
Potato Chip




Part B:

1. Label two test tubes as follows:

2. Place 20 drops of albumin solution in test tube A ???

3. Place 20 drops of water in test tube B.

4. Add 5 drops of Biuret solution to each test tube and record the results.

5. Label four test tubes with the names of your unknown solutions.

6. Add 20 drops of each unknown to the correct test tube

7. Add 5 drops of biuret solution to each test tube.

8. Observe and record your results.

Table 1-2 - Results of Biuret Test for Proteins

Test Tube/Sample
Color of Biuret Solution Before
Color After Addition of Biuret Solution to Sample
Positive or Negative Result
Albumin Solution



Egg solution






Apple Juice



Oatmeal Solution


Analysis Questions:

1. What is a lipid?


2. What do lipids do?


3. What is a protein?


4. What do proteins do?


5. What are proteins made from?


6. What foods should you eat if you want protein?


7. What type of lipids are bad to eat?



Write a paragraph that tells if the objective was met and what was learned from the lab.

 Questions? Comments
Shannon Tice