Testing of food items in Food Component – Class 7 Science Experiment

Chapter Name: Food Component

Activity Name: Testing of food items in Food Component

Activity Description:

In this experiment, we will test different food items for the presence or absence of carbohydrates (starch), proteins, and fats. The goal is to record the information in Table 2 and analyze the components present in the food items.

Required Items:

1. Rice
2. Potato
3. Milk
4. Curd
5. Egg

Step by Step Procedure:

1. Take small samples of each food item (rice, potato, milk, curd, and egg) and place them on separate plates or containers.
2. Test for the presence of starch (carbohydrates): a. Take a drop of iodine solution and add it to each food sample. b. Observe the color change. A blue-black color indicates the presence of starch, while no color change indicates its absence. c. Record the results in Table 2 under the “Starch” column.
3. Test for the presence of proteins: a. Perform the Biuret test for proteins. b. Take a small amount of each food sample and add a few drops of Biuret reagent to each sample. c. Observe the color change. A violet or purple color indicates the presence of proteins, while no color change indicates their absence. d. Record the results in Table 2 under the “Proteins” column.
4. Test for the presence of fats: a. Perform the grease spot test for fats. b. Take a small piece of filter paper and place a small amount of each food sample on separate spots on the paper. c. Let the spots dry for a few minutes. d. Hold the paper up to the light and observe if any translucent spots appear. Translucent spots indicate the presence of fats, while no spots indicate their absence. e. Record the results in Table 2 under the “Fats” column.

Experiment Observations:

Table 2: Testing of Food Items for Carbohydrates, Proteins, Fats

S. No	FOOD	STARCH (Present/Absent)	PROTEINS (Present/Absent)	FATS (Present/Absent)
1	RICE	Present	Absent	Absent
2	POTATO	Present	Absent	Absent
3	MILK	Absent	Present	Present
4	CURD	Absent	Present	Present
5	EGG	Absent	Present	Present

Observations:

1. Rice contains starch but does not contain proteins or fats.
2. Potato contains starch but does not contain proteins or fats.
3. Milk does not contain starch but contains proteins and fats.
4. Curd does not contain starch but contains proteins and fats.
5. Egg does not contain starch but contains proteins and fats.

Note down your observations in below table format

Precautions:

1. Handle chemicals (iodine solution and Biuret reagent) with care and follow safety guidelines.
2. Use fresh food samples for accurate results.
3. Avoid cross-contamination between food samples.
4. Conduct the tests in a well-ventilated area.

Lesson Learnt from Experiment:

Through this experiment, we learned how to test different food items for the presence of carbohydrates (starch), proteins, and fats using simple chemical tests. Understanding the components present in various food items helps us make informed dietary choices and maintain a balanced and nutritious diet.

We also understood the importance of conducting experiments carefully, recording observations accurately, and following safety precautions while working with chemicals and food samples.