Testing For Nutrients Name: __________________

Background: Chemical tests can be used to determine which nutrients are present in a substance.

Objective: Learn how to test substances for the presence of carbohydrates, proteins, vitamin C and fats.

Procedure:

Controls:

A) Mix two drops of each Indicator Solution with 5ml of water in separate test tubes. Note your Observations

in the Controls Table below

Part 1: Testing for Carbohydrates

Starches and sugars belong to the group of compounds called carbohydrates. Starch molecules are composed of many simple sugar molecules joined together. Starch molecules and other sugar molecules have different chemical behaviors. For this reason, different chemical reagents are used to test for starch and simple sugar.

A) Iodine is used to test for the presence of starch. Add two drops of iodine solution to the starch solution

and the glucose solution. Compare with the Control for Iodine and note your observations in the Part 1

table below.

B) Benedict’s solution, a clear blue solution, is used to test for the presence of simple sugars. Add two drops

of Benedict’s solution to the starch solution and the glucose solution. Compare with the Control for

Benedict’s Solution and note your observations in the Part 1 table below.

Part 2: Testing for Fats

The presence of fats in a substance can be detected by using a brown paper bag or Sudan III.

A) Put two drops of vegetable oil onto a piece of brown paper. Compare with the Control for Brown paper

and note your observations in the Part 2 table below.

B) Combine ten drops of vegetable oil with two drops of Sudan III. Compare with the Control for Sudan III

and note your observations in the Part 2 table below.

Part 3: Testing for Vitamin C

Both Iodine and Biuret Reagent with Copper Sulfate can each be used to test for Vitamin C.

A) Add two drops of Iodine to ten drops of vitamin C solution. Compare with the Control for Iodine and note

your observations in the Part 3 table below.

B) Add two drops of Biuret Reagent with Copper Sulfate to ten drops of vitamin C solution. Compare with

the Control for Biuret Reagent with Copper Sulfate and note your observations in the Part 3 table below.

Part 4: Testing for Proteins

Biuret Reagent with Copper Sulfate are used as an indicator of proteins in a food.

A) Add two drops of Biuret Reagent with Copper Sulfate to 4 drops of egg protein solution. Compare with

the Control for Biuret Reagent with Copper Sulfate and note your observations in the Part 4 table below.

Results:

----Controls:

	Iodine	Paper Bag	Sudan III	Biuret Reagent And Copper Sulfate	Benedict’s Solution
Water	Gold	Wet Paper	Dull Pink	Light Blue	Light Blue

Part 1: Testing for Sugars

	Iodine	Benedict’s Solution
Starch	Black	Blue
Glucose	Brown	Green / Yellow / Brick Red depending upon amount of sugar

Part 2: Testing for Fats

	Paper Bag	Sudan III
Vegetable Oil	Bag becomes translucent	Bright Pink

Part 3: Testing for Vitamin C

	Iodine	Biuret Reagent and Copper Sulfate
Vitamin C	Clear Solution	Turns yellow then gray

Part 4: Testing for Proteins

	Biuret Reagent and Copper Sulfate
Egg Protein	Turned Purple

Questions to consider:

1. Why did you apply each test to water first?
2. The nutritional information for Cheddar Cheese Snack Crackers is:

1 Serving provides 210 calories in the form of 12 grams of fat, 23 grams of carbohydrates including starch,

3 grams of protein and 320 milligrams of sodium. One serving provides 6% of the recommended daily intake

of iron, 10% of the daily recommended intake of calcium and is not a source of Vitamin A or Vitamin C.

What observations would you see if you tested this food for:

Starch Test _______________ Fat Test ________________

Vitamin C Test ____________ Protein Test _____________