Souring of milk is aa)Periodic changeb)Undesirable changec)Desirable c...
Souring of milk is an undesirable change.Explanation:Undesirable change:
Undesirable change refers to a change that is not preferred or wanted. It may result in a negative impact on the quality, taste, texture, or appearance of a substance or product.
Souring of milk:
Souring of milk is a natural process that occurs due to the growth and activity of bacteria present in milk. These bacteria, especially Lactic Acid Bacteria (LAB), convert lactose (milk sugar) into lactic acid through a process called fermentation.
Reasons for undesirable change:
There are several reasons why souring of milk is considered an undesirable change:
- Change in taste and smell: Souring of milk leads to a tangy or sour taste, which is quite different from the natural taste of fresh milk. It also results in an unpleasant odor.
- Decreased nutritional value: The process of fermentation during souring of milk can lead to a decrease in the nutritional value of milk, particularly a decrease in the availability of certain vitamins.
- Curdling: Sour milk has a tendency to curdle, forming clumps and separating into solid curds and liquid whey. This curdling makes the milk unappetizing and difficult to consume.
- Reduced shelf life: Sour milk has a shorter shelf life compared to fresh milk. It becomes unfit for consumption and can spoil other food items it comes in contact with.
Prevention of souring:
To prevent the souring of milk and prolong its shelf life, various methods can be employed:
- Refrigeration: Keeping milk at low temperatures slows down bacterial growth and delays the process of souring.
- Pasteurization: Pasteurization is a process of heating milk to destroy harmful bacteria, including those responsible for souring. It helps in extending the shelf life of milk.
- Adding preservatives: Some preservatives, such as potassium sorbate or sodium benzoate, can be added to milk to inhibit the growth of bacteria and prevent souring.
In conclusion,
Souring of milk is an undesirable change due to its negative impact on taste, smell, nutritional value, shelf life, and curdling. Various measures can be taken to prevent or delay the souring process and ensure the milk remains fresh and safe for consumption.