Rennet facts for kids

Rennet is a special mix of enzymes that helps turn milk into solid curds. Think of it like a magic ingredient that makes cheese! These enzymes are naturally found in the stomachs of young mammals, like calves. For a long time, rennet from animals was the main way people made cheese.

Today, rennet is super important for making many types of cheese. It helps separate the solid parts of milk (curds) from the liquid parts (whey). This process is the first big step in making delicious cheese. Besides cheese, rennet can also be used in some other foods, like certain desserts.

What is Rennet?

Rennet is mainly made of an enzyme called chymosin. Enzymes are like tiny workers in our bodies and in nature that help speed up chemical reactions. In the case of rennet, chymosin helps break down a protein in milk called casein. When casein breaks down, it causes the milk to thicken and form curds.

How Rennet Works in Cheesemaking

When rennet is added to milk, it starts a process called coagulation. This means the milk begins to clump together and form a gel-like substance.

• First, cheesemakers warm the milk to the right temperature.
• Then, they add a small amount of rennet.
• After a short time, the milk changes from a liquid to a soft, jelly-like mass.
• This mass is then cut into smaller pieces, which helps more of the liquid whey drain away.
• The remaining solid curds are what cheesemakers use to make cheese.

Types of Rennet

Over time, people have found different ways to get rennet or similar enzymes.

Animal Rennet

Traditionally, animal rennet comes from the fourth stomach of young, milk-fed calves. This type of rennet has been used for thousands of years to make cheese. It's known for giving cheese a specific flavor and texture.

Microbial Rennet

In the 20th century, scientists found that some microorganisms, like certain fungi and bacteria, can produce enzymes that work like chymosin. This led to the creation of microbial rennet. It's a good option for people who prefer not to use animal products, like vegetarians.

Vegetable Rennet

Some plants also contain enzymes that can curdle milk. Examples include certain types of thistle, fig trees, and nettles. Vegetable rennet has been used in some traditional cheese recipes, especially in areas where animal rennet was not common. However, it's less common in large-scale cheese production today.

Fermentation-Produced Chymosin (FPC)

This is the most common type of rennet used today, especially in big cheese factories. FPC is made using genetic engineering. Scientists take the gene for chymosin from a calf and put it into a microorganism, like a yeast or a bacterium. These microorganisms then produce large amounts of pure chymosin, which is exactly like the enzyme found in animal stomachs. FPC is very efficient and consistent, making it a popular choice for cheesemakers worldwide. It's also suitable for vegetarians because no animals are involved in its production.

History of Rennet

The discovery of rennet's power was probably an accident! Imagine ancient people carrying milk in bags made from animal stomachs. They might have noticed that the milk inside these bags turned into curds and whey. This was because the natural enzymes in the stomach lining were working on the milk.

The earliest records of cheesemaking go back thousands of years, to around 8,000 BCE, when humans first started keeping animals like sheep and goats. The use of rennet made it possible to store milk in a solid form, which was very useful before refrigerators existed. Cheese became an important food source for many ancient civilizations, including the Egyptians, Greeks, and Romans.

Images for kids

• 

  Animal rennet to be used in the manufacture of cheddar cheese

See also

In Spanish: Cuajo para niños