Question

Milk can be preserved by ____________
(a)Pasteurization
(b)Drying
(c)Chemical preservatives
(d)Freezing

Answer 1

Hint: The method of milk preservation is used to increase the shelf life of milk longer. This is done by eliminating pathogens from the milk so that they won’t spoil the milk. This method was invented by the French microbiologist Louis Pasteur.

Complete answer:
Milk is preserved by the method of pasteurization. Pasteurization is named after its inventor Pasteur and is done to kill bacteria from milk, thus preserving it for a longer time. In this process, foods such as milk and fruit juice are treated with mild heat (less than $100°C$). Due to this, pathogens are killed, and also the enzymes responsible for spoiling or curdling milk become denatured. It also ensures that pathogenic microorganisms that can cause diseases in humans are also eliminated. This is a way of making sure products are safe for a longer time in an inexpensive way.

Additional Information: Let us look in detail at the steps of pasteurization.
-Chilling: Milk is chilled to prevent any further growth of bacteria before heating it.
-Preheating: Preheating is done to easily separate out the butterfat.
-Clarification: This is basically a filtration step in which large solid particles are strained out from the milk.
-Standardization: This is the process in which butterfat is separated from milk
-Homogenization: This is the physical process in which the fat globules of milk are broken down into tiny droplets.
-Heating: This is the step where heating is done to kill pathogens especially Clostridium botulinum spores.
-Cooling: The milk is now cooled to $4°C$ to give a temperature shock after which packaging takes place.
So, the correct option is ‘Pasteurization’.

Note: -Louis Pasteur is also the scientist who disproved the theory of abiogenesis using his swan-neck experiment.
-He instead gave the theory of biogenesis which states that living beings come from pre-existing living beings.
-Whereas the theory of abiogenesis stated that living organisms arise out of non-living things spontaneously.