Preservation of Food

Food Preservation Methods for Class 5 Science

This concept deals with various food preservation methods. The students will be introduced to various methods that increase the shelf life of fruits, meat, fish etc.

After reading the concept, students will be able to:

• Understand how do microorganisms spoil food.
• Recall food preservatives examples and can explain how they are used to preserve foods.
• Know about chemical food preservatives.
• Understand what is canning food preservation, drying food preservation and freezing food preservation.
• Know what is pickle and how various types of foods are preserved as pickles.
• Understand what is pasteurization and why pasteurized milk is better for consumption.

Each concept is explained to class 5 students using descriptions, illustrations, and concept maps. After you go through a concept, assess your learning by solving the two printable worksheets given at the end of the page.

Download the worksheets and check your answers with the worksheet solutions for the concept of Food Preservation Methods provided in PDF format.

The process by which food is prevented from spoiling or rotting due to the growth of microbes like bacteria and fungi is called food preservation.
The objectives of food preservation are—

• Increasing the shelf-life of food.
• Keeping the nutritional value of food intact.
• Enabling the storage and supply of stored food for a longer period.

Bacteria and fungi are the main groups of decomposers that are responsible for the spoilage of food.
These microbes require warmth and moisture for multiplication. Hence, food preservation methods have been adopted, keeping these factors in mind.

Depending on the nature of food to be preserved, there are different methods of food preservation—

• Freezing
• Canning
• Pickling
• Adding sugar
• Adding salt
• Dehydration/Drying
• Adding preservatives
• Pasteurization

Freezing:

Freezing is the method of storing food at extremely low temperatures, which prohibits the bacteria and fungi from multiplying.

 

 

• The food items that are preserved by freezing are— Meat, fish, fruits, vegetables, packaged food.

Canning:

Canning is the method of sealing food in air-tight containers. Oxygen in air leads to rotting of food.
In canning, the absence of air does not allow the growth of microbes.The food items that are preserved by canning are—Chopped fruits and vegetables, fish, meat, poultry, seafood, and dairy products.

 

Pickling:

The ingredients used while making pickles prevent the growth of microbes. The common ingredients used are oil, vinegar, salt, and spices.Vinegar in pickles is too acidic and hence, not suitable for microbial growth.Oil prevents air from reaching the pickle, which prevents the growth of microbes.Pickles are made of the following food items—Raw mango, radish, carrot, beetroot, ginger, garlic, lemon, meat, fish, etc.

 

Adding sugar:

After removing water from the fruits, huge amounts of sugar are added to make jams, marmalades, and jellies.
Adding sugar checks the growth of microbes and preserves the flavour and colour of fruits.

 

Adding salt:

Salt absorbs water from foods, making the food too dry to support the growth of harmful moulds or bacteria.The food items that are preserved by adding salt—Fish, meat, poultry, raw fruits like mango, etc.

 

Dehydration/ Drying:

Some food items are dried in the sun or passed through hot air.Drying removes moisture and thereby prevents microbial growth.The food items that are preserved by drying—Cereals, pulses, chips, fish, vegetables like beans, etc.

 

Adding Preservatives:

• Preservatives are chemical substances that are used to increase the shelf-life and prohibit the spoilage of different food items.
  Generally, all canned or packed foods contain chemical preservatives. These preservatives are carefully monitored and are used in specific amounts.
• Some common food preservatives used are—Sorbates (calcium and sodium sorbate), Benzoates, and Nitrites.
• They all prevent the growth of microbes and maintain the quality of food.

Pasteurization:

This method is used to preserve milk, and includes the following steps:

• Boiling milk at high temperature so that unwanted microbes get killed.

Chilling the milk quickly for package and storage.

 

 New Words

 

Did You Know?

• Food can be preserved by freezing for almost 3-12 months.
• Salt, sugar, vinegar, and castor oil are natural preservatives used to preserve food for long durations.
• Preservation of food by adding salt is the oldest method known for food preservation.