Why does rennin turn milk into cheese?

Rennin, also known as chymosin, doesn't directly "turn" milk into cheese. It plays a crucial role in the process, but it's not the only factor. Here's a breakdown:

Rennin's Role:

* Clot Formation: Rennin is an enzyme that specifically targets the protein casein in milk. It breaks down casein into smaller fragments, called para-kappa-casein and kappa-casein. This breakdown alters the structure of casein, causing it to clump together and form a solid curd.

* Separation: The curd separates from the liquid whey, which contains lactose, water-soluble proteins, and other milk components.

The Complete Cheesemaking Process:

1. Milk Preparation: Milk is heated to the appropriate temperature, typically around 30-35°C (86-95°F), to optimize enzyme activity.

2. Rennin Addition: Rennin is added to the milk. The amount of rennin used depends on the type of cheese being made.

3. Curd Formation: The rennin breaks down casein, forming the curd. This process takes some time, typically 30 minutes to an hour.

4. Cutting and Stirring: The curd is cut into small pieces to release whey and promote further coagulation.

5. Heating: The curd is heated to a specific temperature to encourage further whey separation and texture development.

6. Draining: The whey is drained off, leaving the curd behind.

7. Salting: Salt is added to the curd to flavor the cheese and inhibit bacterial growth.

8. Pressing: The curd is pressed to remove excess moisture and develop the cheese's texture.

9. Aging: The cheese is aged for a specific period to allow flavors to develop and textures to mature.

Key Points:

* Rennin is a key ingredient, but not the only one. Other factors, such as milk type, bacterial cultures, temperature, and aging, all contribute to the final cheese characteristics.

* Rennin is not always used in cheesemaking. Some cheesemakers use other enzymes, like animal rennet, or even microbial rennet, to achieve similar results.

* The cheesemaking process is complex and involves many steps. The result is a diverse range of cheeses with different textures, flavors, and properties.

Therefore, it's more accurate to say that rennin initiates the crucial curd formation step in cheesemaking, but it's not the sole factor responsible for creating cheese.