NUTRIENT TESTS - CARBS
HOW TO DETECT VARIOUS MACROMOLECULES
Carbohydrate (Sugar) Tests - Testing for reducing sugars and starch
Reducing sugars have a structure that allows them to "reduce" copper
ions found in Benedict's solution. This results in a colour change. Most
monosaccharides and some disaccharides are reducing sugars.
REDUCING SUGAR
OBSERVATIONS
1. Add equal amounts of each sugar
solution to a test tube.
2. Add approximately 10 drops of
Benedict's solution to each test tube.
Note the colour of the solution.
3. Place the test tubes in a hot water
bath of approximately 60-80 C for 5
minutes.
4. Note any colour changes after.
STARCH TEST
1. Add 3 drops of each solution to the
spotting plate. Label the spotting plate
accordingly as it will be easy to
confuse the samples.
2. Add 1 drop of iodine to each well in
the plate.
3. Note any colour changes.
Nutrient Testing - Sugar
OBSERVATIONS
NUTRIENT TESTS - LIPIDS
HOW TO DETECT VARIOUS MACROMOLECULES
Lipid test - Testing for lipids (non-polar substances)
Non-polar substances dissolve with non-polar solvents. Sudan IV is a
non-polar dye (solute) that will dissolve in solutions that are nonpolar. Lipids will also leave a stain on regular paper after it has
completely dried.
SUDAN IV TEST
OBSERVATIONS
1. Add 5 mL of distilled water to each
test tube.
2. Add 2 mL of food sample to each
labelled test tube.
3. Add a small amount of Sudan IV dye to
each test tube.
4. Invert the test tube to mix.
PAPER TEST
1. Draw and label circles a piece of blank
paper and label each circle
underneath.
2. Place a drop of each sample to fit in
the circle.
3. Wait for the samples to dry
completely.
Nutrient Testing - Lipids
OBSERVATIONS
NUTRIENT TESTS - PROTEIN
HOW TO DETECT VARIOUS MACROMOLECULES
Protein test - Testing for peptide bonds
In the presence of peptide bonds and proteins, Biuret solution will
turn from a blue colour to a pinkish/purple colour. The Biuret solution
contains copper ions that interact with the peptides in the solution to
form a complex. This is what gives a pink/purple colour.
BIURET TEST
1. Add 5 mL of distilled water to each
test tube.
2. Add 2 mL of food sample to each
labelled test tube.
3. Add 10-15 drops of Biuret solution.
4. Note any colour changes.
Nutrient Testing - Protein
OBSERVATIONS