Preservation by Sun-Drying, Heating, Cooling

Question 1 Name food material which can be preserved by heating?

Question 2 Name food material which can be preserved by cooling?

Question 3 Name food material which can be preserved by sun-drying?

Question 4 How do you preserve food by heating?

Question 5 How do you preserve food by cooling?

Question 6 How do you preserve food by dehydration?

• NCERT Solutions Class 8 Science

1) Preservation by Sun-drying or Dehydration

Drying means removal of water from food materials which are to be prepared. It reduces the water content of food material and makes them dry. In the absence of moisture, the food does not get spoiled because the micro-organism which spoil food do not grow in dry food.

The vegetables like spinach, methi leaves, cauliflower, peas are preserved in our homes by the sun-drying method. These dries vegetables can be stored safely for a long time and used whenever required.

2) Preservation of Food by Heating

Heating kills many micro-organism and prevents the food from spoilage.

For Example: We boil milk to prevent it from spoilage. When we heat the milk during boiling, then the food-spoiling bacteria present in it gets killed.so the boiled milk remains good for a longer time.

3) Preservation of Food by Cooling

Low temperature inhibits the growth of micro-organism. The food spoiling bacteria do not grow and multiply in cold condition. When food is kept in a cold place then the food does not get spoiled easily. The food material like milk, kneaded flour, cooked food and fresh fruits and vegetables are kept in a cool place like refrigerator to prevent their spoilage.

Other Notes from Chapter 2 Micro Organisms Friend and Foe

• Micro-Organisms
• Groups of Micro Organism
• Where do Micro Organism Live
• Useful Micro organism
• Making of Curd and Bread
• Commercial Use of Micro organism
• Medicinal Use of Micro oragnaism
• Increasing Soil Fertility
• Cleaning the Environment
• Harmful Micro Organism
• Carriers of Disease causing micro organism
• Disease Causing Micro organisms in Animals
• Disease Causing Micro-Organism in Plants
• Food poisoning
• Preservation of Food
• Preservation by Deep Freezing,Common Salt, Sugar
• Preservation of food by mustard oil and Vinegar, Chemicals, Pasteurisation, Air-tight Packets
• Nitrogen Fixation
• Nitrogen Cycle