Question

How is curd made? Is this change reversible?

Answer 1

Hint:Explain the process of curd formation and the chemical processes involved in it. Also, tell whether the changes occurring in the formation of curd are reversible or irreversible.

Complete step by step answer:
As we know that curd is a dairy product and it is obtained by coagulating milk in the process which is known as curdling. And that coagulation of milk can be caused by adding any edible acidic substance such as lemon juice, vinegar and then it is ready for coagulation.
Curd or Dahi is a fermented milk product formed by fermentation of milk by Lactic Acid bacteria to Lactic acid. Milk consists of globular proteins called casein. The curd forms because of the chemical reaction between the lactic acid bacteria and casein. During fermentation, the bacteria uses enzymes to produce energy (ATP) from lactose. The byproduct of ATP production is lactic acid. Lactic acid acts on the globular proteins present in the milk and denatures them. And hence this denaturation destroys the tertiary and quaternary structures of proteins and the globular proteins are converted into fibrous proteins thus giving a thick texture to the milk due to coagulation of the proteins.
Here you will find the easiest method to make curd even at home. You guys try this process. It is very cool out.
So firstly take a larger pot and pour some milk to it. Rinsing the pot reduces the changes of milk solids to boil on a low to medium flame.
Keep stirring to reduce the formation of layers of cream. Usually boil the milk on medium flame.
When the milk comes to a boil, then reduce the flame to very low and allow it to simmer for 10 to 15 min.
Then, remove it from the stove and allow it to cool down at a warm temperature.
After that you will observe your curd is ready. And the curd from milk cannot be changed into milk again. So, this is an irreversible change which cannot be changed. As in this change the product so obtained can’t be changed to its original forms. As once changed into curd, we can’t change it back to milk. Thus, it’s an irreversible change.


Note:
Don’t get confused between reversible and irreversible changes. As reversible changes explain us about that changes which are made physically and which can be reversed or undone.
If we take an example of reversible reaction then that is freezing of water to make ice.