Name: _______________________________________
Per. _____
#13 Nutrient Lab
INTRODUCTION:
Organic compounds are made of carbon and are often called "Life Molecules." They are found in all living
organisms and are consumed in the foods we eat and digest. Organic compounds are categorized as either:
1. Carbohydrates
2. Proteins
3. Lipids
4. Nucleic acids
Simple chemical experiments, using testing solutions known as indicators, can be conducted to determine
whether common foods contain any of the above organic compounds.
All foods can be classified as lipid, protein, carbohydrate or nucleic acid but some foods can contain more
than one type of organic compound. Therefore, some foods could test positive for more than one type of organic
compound.
PROBLEM: What organic compounds are found in the following common household foods?
HYPOTHESIS:
Food Solutions
Starch
Carbs
Mono
Protein
Lipids
because……
Corn Syrup
Gelatin
Vegetable Oil
Egg Whites
Milk
Potato
Oatmeal
Soda
Unknown
MATERIALS:
safety glasses
6 test tubes
test tube holder
test tube rack
masking tape
eyedroppers
Indicators:
Iodine
Benedict’s Solution
Biuret Agent
Brown Paper Bag
Food solutions:
Starch
Corn syrup
Gelatin
Vegetable oil
Egg whites
Milk
Potato
Oatmeal
Soda
Unknown
PROCEDURE:
Part A: Testing for Carbohydrates
1. Using clean test tubes and masking tape, label them 1 and 2. Place 10 drops of water in test tube #1. Place
10drops of starch solution in test tube #2.
2. Add 5 drops only of iodine indicator to each test tube.
3. Swirl each test tube gently and let stand for 2 minutes.
4. After 2 minutes, any food containing carbohydrates will turn bluish-black. Note the color of each test tube and fill in the data table.
5. Wash out all test tubes.
Part B: Testing for Monosaccharides (Simple Sugars)
1. Using clean test tubes, label them 3 and 4. Place 10 drops of water in test tube #3. Measure 10 drops of corn
syrup and place in test tube #4.
2. Add 10 drops only of Benedict’s solution to each test tube.
3. Swirl each test tube gently. Using test tube holders, carry the test tubes to the hot water bath.
4. Heat the test tubes in a boiling water bath for at least 5 minutes.
5. After 5 minutes, any food containing simple sugars will turn green, orange, red, or brown. Note the color of
each test tube and fill in the data table.
6. Wash out all test tubes.
Part C: Testing for Proteins
1. Using clean test tubes, label them 5 and 6. Place 10 drops of water in test tube #5. Again, measure out 10
drops of gelatin into test tube #6.
2. Add 10 drops of Biuret indicator to each test tube.
3. Swirl test tubes for 30 seconds gently and let sit for 2 minutes each.
4. Any test tube that contains protein will become a purple color. Note the color of each test tube and complete
data table.
5. Wash out all test tubes.
Part D: Testing for Lipids
1. Obtain 2 paper bag squares.
2. Place drop of H2O on one and drop of vegetable oil on the other. Let sit for 1 minute.
3. Pick up the paper bags, and put them up towards the light. Any food solution that contains lipids will appear
translucent.
4. Record the color of the paper bag square in the data table and discard bag squares.
Part E: Testing Additional Foods for Each Nutrient
Now that you are familiar with the four nutrient tests, you will perform all 4 tests on the following food items.
Bring test tube rack with labeled test tubes to the main station. Use pipette to measure out 10 drops of each
solution into test tubes #1-6. To save time, conduct one test for test tubes #1-6. Then clean test tubes #1-6 and
move on to the next test.
Clean lab area, wash hands with water and soap and put all materials away.
ANALYSIS AND CONCLUSION:
Please write your answers in regards to your lab results.
1. What is the indicator for carbohydrates?
2. What color change represents a positive test for carbohydrates?
3. Which foods contain carbohydrates?
4. What is the indicator of monosaccharides?
5. What color change represents a positive test for monosaccharides?
6. Which foods contain monosaccharides?
7. What is the indicator for proteins?
8. What color change indicates a positive test for proteins?
9. Which foods contain proteins?
10. What is a positive test for lipids?
11. Which foods contain lipids?
12. Why do you think water was used as one of the solutions?
13. What is your guess for the unknown? Explain your reasoning.