Overview of Indicator Tests
Various tests are available which allow us to determine if certain food
substances are present in different solutions. The directions for using
each of these tests are written below. Use the tests below on each of
the food substances to learn which test corresponds with each type of
food.
Before you start, make sure that you carefully keep track of what type
of substance you are testing. You will complete all four tests on all four
substances and use the data you collect to determine which food gives a
positive result for each test.
Directions for using each of the tests:
Paper Test
Label a square of brown paper or a piece of brown paper towel with the
name of the substance you are testing. Place one drop of the liquid food
substance onto the paper. Wait until the liquid dries. Check back to see
if the food has left a spot.
Biuret Test (by-er-et)
Fill one well of the spot plate halfway full with the liquid food substance.
Add 5-10 drops of the light blue Biuret indicator. Wait a few minutes and
then record the color of the indicator.
Iodine Test
Fill one well of the spot plate halfway full with the liquid food substance.
Add 3-5 drops of the orange iodine indicator. Record the color of the
indicator.
Test-Tape Test
Fill one well of the spot plate halfway full with the liquid food substance.
Dip the turquoise end of the test-tape into the liquid and then take it
out. Wait a few minutes for the test-tape to dry off. Record the color of
the test-tape strip.
Record the initial and final appearance of the indicator, NOT the appearance/color of the
food substance.
Liquid Food
Substance
Protein
Starch
Sugar
Fat
Paper Test
Biuret Test
Iodine Test
Test-Tape Test
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Results:

The Paper Test can be used to indicate the presence of ________________.
A positive result for the Paper Test is when the paper changes from
________________to ___________________.

The Biuret Test can be used to indicate the presence of ________________.
A positive result for the Biuret Test is when the Biuret changes from
________________to ___________________.

The Iodine Test can be used to indicate the presence of ________________.
A positive result for the Iodine Test is when the iodine changes from
________________to ___________________.

The Test-Tape Test can be used to indicate the presence of ________________.
A positive result for the Test-Tape Test is when the test-tape changes from
________________to ___________________.