The
McMush Lab
Background: Carbohydrates, proteins, fats, vitamins and other nutrients provide our bodies with
energy necessary to carry out life activities. These compounds are present in the plants and animal that
we use for food. In this lab, we will test for specific organic and inorganic compounds and then
determine if those compounds are present in ordinary foods.
Purpose: This lab activity provides an opportunity for the development of skills involved in
chemically testing for the presence of the carbohydrates, lipids and proteins found in food samples.
You will test for these macromolecules using the following reagents: Biuret solution, Benedict’s
solution, Lugol’s iodine and silver nitrate. Once familiar with the detection techniques, you will apply
those techniques to the slurry that has been made by blending a complete Happy Meal (minus the toy,
of course). Using the skills that you have developed you should be able to determine which organic
compounds are present in the slurry.
Materials:
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McDonald’s Happy Meal (fries, burger and soft drink included)
300ml beakers
25ml graduated cylinders
test tubes and test tube clamps
masking tape and markers
Benedict’s Solution
Biuret Solution
Brown paper bag
Lugol’s Iodine Solution
1% Silver Nitrate Solution
Blender
SAFETY :
 you must wear eye protection
 point test tubes away from all people when heating samples
 handle hot test tubes with test tube clamps
 caution: iodine and silver nitrate stain skin and clothing
Procedure:
In order to determine which nutrients are in a sample of McMush, we need to know what a positive test looks
like for each of the macromolecules being tested. The first part of this experiment involves conducting nutrient
tests on known food samples.
Part One: Testing of Known Substances
Protein Test: Egg white (aka albumin) contains several amino acids necessary for growth and
development.
1. Place 5ml of albumin solution into a test tube.
2. Add 10 drops of Biuret Solution
3. Observe any colour change. Record results in Table 1.
Glucose Test: Glucose is a monosaccharide (a simple carbohydrate) that provides organisms with
energy. It is absorbed into the bloodstream through the intestinal wall after the digestion of
carbohydrates
1. Place 5ml of glucose solution into a test tube
2. Add 3ml of Benedict’s Solution.
3. Place the test tube in a hot water bath for 5 minutes. Use test tube clamps to handle hot test
tubes
4. Observe any colour change. Record results in Table 1.
Starch Test: Starch is a complex carbohydrate. It is often found in plants and food items such as
beans, bread, pasta, potatoes and rice. It is also used as an additive for food processing.
1. Place 5ml of Starch Solution into a test tube.
2. Add 5 drops of Lugol’s Iodine Solution
3. Observe any colour change. Record results in Table 1.
Lipid Test: Lipids include fats (solid at room temperature) and oils (liquid at room temperature). Fats
and oils are made of smaller units called triglycerides which are composed of a glycerol and three
fatty acid molecules.
1. Place 1 drop of vegetable oil on a piece of brown paper bag.
2. Add a drop of water on another section of the bag.
3. Allow the drops to air dry or use a hair dryer. If a translucent stain remains, fat is present.
Sodium Chloride Test: Sodium Chloride (aka table salt) is found in oceans and in the fluids outside
of cells. It is used in foods to add flavor and as a preservative.
1. Place 5ml of the Salt solution into a test tube
2. Add 5 drops of silver nitrate solution
3. Observe any colour change
Table 1: Positive test results for each of the nutrients tested using the reagents indicated
Food Substance Nutrient Present
Reagent Test
Observation (indicate
initial and final colour)
Egg white
protein
Biuret Solution
Glucose
monosaccharide
Benedict’s Solution
Starch
polysaccharide
Lugol’s Iodine Solution
Vegetable oil
lipid
Brown paper bag
Salt solution
NaCl
Silver Nitrate Solution
Part Two: Testing for macromolecules in McMush
1. Place a McDonald’s Happy Meal in a blender. Add enough water to cover and blend until you
get an emulsion (a good thorough mixture)
2. Filter the mush into a beaker.
3. Conduct the 5 reagent tests from Part 1 using 5ml of the McMush Solution. Record your
observations for each test in Table 2 below.
Table 2: Colour change observed after exposing McMush solution to various chemical reagents
used to test for the presence of food nutrients
Reagent Test
Results
Conclusion
(presence or absence of nutrient)
Biuret Solution
Benedict’s Solution
Lugol’s Iodine Solution
Translucency test
Silver Nitrate Solution
Post Lab Discussion: Answer on a separate sheet of paper
Log on to http://nutrition.mcdonalds.com/nutritionexchange/nutritionfacts.pdf
and
http://www.mayoclinic.com/health/healthy-diet/NU00200 to get the information needed to
answer the following questions.
1. Fill in the following table which illustrates the nutritional information for a McDonald’s
Happy Meal.
Food Item
Serving
Size
Cheeseburger
Small fries
2 Ketchup
packets
Child size
Coca-cola
TOTAL
for 1
meal
Calories
Total
Fat
(g)
Total
Carbohydrates
(g)
Total
Protein
(g)
Sodium Cholesterol
(mg)
(mg)
2. What percentage of a child’s daily calories requirements (assume 1500 calories) does this
ONE meal constitute?
3. Compare the total fat, protein, carbohydrate, sodium and cholesterol intake from the Happy
Meal with the recommendations outlined in the Mayo Clinic website. Use the lower value
cited for each macromolecule since we are assuming this meal is for a child. For example, it
is recommended that total carbohydrate consumption be between 225-325 g per day. Use
225 g as the basis for comparison.
From ONE Happy Meal
Mayo Clinic
Recommendations
Total Fat (g)
Total Carbohydrates (g)
Total Protein (g)
Total Sodium (mg)
Total Cholesterol (mg)
Use the above comparisons to discuss the following: Do you believe the Happy Meal
investigated in class is nutritionally balanced and would you recommend it for consumption
by the school aged children who generally order such a meal. Support your opinion with
scientific facts and reference any resources you use. Aside from obesity, what other health
problems can children develop as a result of ignoring the recommendations outlined by
doctors and nutritionists?
4. If you had no choice but to take your child to McDonald’s for lunch, what would be a
healthier alternative to the Happy Meal? Include a main dish, side dish, drink and dessert.
Explain the reasons for your selections.
5. Write the ABSTRACT for the scientific investigation we conducted.