SBI3CIdentifying Nutrientsnames ______

Purpose: a.To study positive tests (tests indicating the presence of a substance) for

carbohydrates, lipids and proteins.

b.To discover which nutrients are found in some common food.

PART 1: CARBOHYDRATES

A) Simple Sugars Test

Materials:Benedict’s reagent; glucose solution; water (control); test tubes; hot plate; Safety Goggles

large beaker of water; the following foods: (List the foods you used)

______

Procedure:1. Prepare a water bath by heating 200 mL of tap water in a 400 mL beaker on a hot plate.

Heat the water on high (to between 80°C & 100°C).

2. Using 2 test tubes - place about 2 mL (2cm high) of water in one test tube –label it “water”.

Put the same volume of glucose in the other each test tube –label it “glucose”.

3. Add 10-15 drops of Benedict’s reagent to each test tube.

4. Place the test tubes in the water bath for 5 minutes. Observe and record any changes.

5. Remove the test tubes and allow them to cool. Record your final observations.

6.Repeat steps 2 to 5 using at least 3 different foods instead of water & glucose.

Observations:

Substance / Observations
Water
(Control)
Glucose
(positive test)
Substance / Observations

B) Starch Test

Materials: Iodine solution;starch suspension; water (control); spot plate; eyedropper; Safety Goggles;

the following food (List the foods you used):

______

Procedure: 1. Place a few drops of each substance into the spot plate wells

(substances include potato starch, water and at least 3 other foods).

2. Add a drop of iodine solution to each substance.

3. Record your observations.

Observations:

Substance / Observations
Water
(control)
Potato Starch
(positive test)
Substance / Observations

Part 2: PROTEINS

Materials:Biuret reagent; albumin; water; spot plates; & Safety Goggles; and the following foods:

______

Procedure: 1.Place a few drops of each substance into the spot plate wells

(substances include albumin, water and at least 3 other foods).

2. Add 2 to 3 drops of Biurets reagent to each substance.

3. Record your observations

Observations:

Substance / Observations
Water(control)
Albumin(positive test)
Substance / Observations

PART 3: LIPIDS

A) Translucence Test

Materials: brown paper; water; vegetable oil; & the following foods:

______

Procedure: 1. Draw a circle approximately 5 cm in diameter.

2. Place a drop of the substance in the centre.

3. Label the circle.

4. Repeat for the other substances.

5. Set the paper aside to dry.

6. Hold each paper up to the light and record your observations.

Observations:

Substance / Observations
Water
(control)
Vegetable Oil
(positive test)
Substance / Observations

Analysis:

  • Use your observations to do the following.
  • Answer with complete thoughts using your own words (no copying)
  1. Why must each reagent be tested with water (the control)? Explain your answer fully.
  1. Which of the substances tested contained the largest number of different nutrients? Explain your answer fully.
  1. Which of the substances tested contained the fewest number of nutrients? Explain your answer fully.
  1. Which of the substances tested is the most nutritious? Give reasons for your answer.

Use your observations and your knowledge of nutrition to clearly explain and justify your answer.

Think about which food has the greater number of nutrients & which has the best quality nutrients

You may consider researching your answer (text book, internet).