Food Tests
You are going to test 5 different foods for the presence of starch, sugar, protein and fat.
The foods you will be testing are:
 Olive oil
 Egg white
 Apple
 Potato
 Milk
Remember to crush the apple and potato separately with the mortar and pestle.
1.
Testing for Starch
 Put a piece / drop of each food type on the Petri dish.
 Add a drop of iodine to each and record your observations in the table.
2. Testing for Sugar Label your 5 test tubes A, B, C, D & E.
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Add 4ml of Benedict’s solution to each test tube.
Put a crushed piece of potato in A.
Put a crushed piece of apple in B.
Put 4ml of olive oil in C.
Put 4ml of egg white in D.
Put 4ml of milk in E.
Carefully place your test tubes in the water bath for 10 minutes.
Carry out test 3 (testing for protein) while you wait.
Record your observations in the table.
3. Testing for Protein
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Label your 5 clean test tubes A, B, C, D & E.
Add 5ml of sodium hydroxide (NaOH) solution to each test tube.
Add a few drops of copper sulphate (CuSO4) to each test tube.
Put a crushed piece of potato in A.
Put a crushed piece of apple in B.
Put 4ml of olive oil in C.
Put 4ml of egg white in D.
Put 4ml of milk in E.
Record your observations in the table.
4. Testing for Fat
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Label your 5 clean test tubes A, B, C, D & E.
Put a crushed piece of potato in A.
Put a crushed piece of apple in B.
Put 4ml of olive oil in C.
Put 4ml of egg white in D.
Put 4ml of milk in E.
Add 5ml of ethanol into each test tube.
Add 5ml of water and shake.
Record your observations in the table.
Results Sheet
Name: ______________
OBSERVATIONS
Type of
food
Potato
Apple
Olive oil
Egg white
Milk
Starch test
Sugar test
Protein test
Fat test
Conclusion
ANSWER KEY
OBSERVATIONS
Type of
food
Starch test
Sugar test
Protein test
Fat test
Conclusion
Potato
Iodine turns from
brown to black
Benedict’s solution
remains blue
Remains blue
Solution stays clear
Potatoes contain
starch
Apple
Iodine remains
brown
Benedict’s solution
turns from blue to
brick red
Remains blue
Solution stays clear
Apple contains
sugar
Olive oil
Iodine remains
brown
Benedict’s solution
remains blue
Remains blue
White layer forms
Olive oil contains
lipids
Egg white
Iodine remains
brown
Benedict’s solution
remains blue
Turns from blue to
Egg white contains
Solution stays clear
lilac
protein
Milk
Iodine remains
brown
Benedict’s solution
remains blue
Turns from blue to
lilac
White layer forms
Milk contains fat
and protein