What is rancidity in chemistry class 10

In daily life, you may have experienced unpleasant odour or flavour in food items, making them taste bad. Have you ever thought about why this happens?. In this article, We will discuss the topic and help you understand what is rancidity?

What is Rancidity 

 

Rancidity is a common term that refers to spoilage of food. It is a chemical process that occurs in fats and oils present in food items when they are exposed to air(oxygen) and light, heat or moisture.

 

The microorganisms oxidise the fat and oil present in the food items, so due to oxidation odour and flavours become unpleasant.

 

Rancidity cause the formation of harmful compounds that may have ill effects on health.

 

What are the causes of rancidity?

The main causes of rancidity are oxidation and hydrolysis of food items.

When food items are exposed to air(oxygen). Oxygen reacts with unsaturated fatty acids present in fats and oils, causing them to break down and form free radicals.

As a result, food items become rancid and their odour and flavour become bad.

 

The other cause is hydrolysis when food items are exposed to water mainly moisture in the air, causing the break of fatty acids and release of free radicals which lead to rancidity.

 

Apart from these, heat and light and microorganisms also spoil food items.

Types of rancidity

On the basis of factors affecting food items, rancidity is of three types-

1. Oxidative rancidity

2. Hydrolytic rancidity

3. Microbial rancidity

 

1. Oxidative rancidity – When food items are stored in containers that are not airtight, the food items come in contact with oxygen in the air. This leads to the breakdown of unsaturated fatty acids in the fat and the release of free radicals. The food items become rancid.

2. Hydrolytic rancidity: - When food items are exposed to water in the form of moisture in the air, leads to the breakdown of fatty acids and the release of free radicals. The food items become rancid.

3. Microbial rancidity: - Microorganisms such as bacteria, yeast or fungi break down fats and release compounds that result in rancidity.

 

Prevention of rancidity

Rancidity spoils food items and makes them smell and taste unpleasant. Rancidity can be prevented by the  following  methods –

   1. Store food items in airtight containers. so food items do not come in contact with oxygen.

    

   2. Microorganisms are more active at temperature . at lower temperatures their activities become slow, so food items are kept in the refrigerator.

   

   3. Keep food products in cool, dark places.

   

   4. Nitrogen gas is filled in packaged food items because nitrogen is an inactive gas so it prevents the oxidation process.

    

  5. Use vacuum-sealed packaging.

     

    Related Topics

1. What happens during a chemical reaction

    FAQs

    1. How to prevent rancidity?

Ans.-  Rancidity can be prevented by keeping food items in airtight containers and refrigerators.

   

    2. What are the main causes of rancidity?

Ans.-  Rancidity is caused by various factors like air, light, heat and microorganisms.

   

    3. What are the main types of rancidity?

Ans.- Rancidity is of three types – Oxidative, hydrolytic and microbial.

   

    4. Give an example of rancidity.

Ans.- When bags or packet containing chips, or wafers is exposed to air which results in a change in odour and taste.

   

    5. Why nitrogen gas is filled in packets of chips?

Ans. Nitrogen is an inactive gas so it slows down the oxidation process in packaged food items.