Beginner’s Guide to Rennet for Cheesemaking
Rennet is a crucial ingredient in cheesemaking, responsible for separating milk into solid curds and liquid whey. Here’s what you need to know as a beginner:
What is Rennet?
Rennet is a coagulant containing the enzyme chymosin, which causes milk to curdle and form curds. It is used to extract the maximum amount of milk solids (curds) from milk during cheesemaking.
Types of Rennet
There are several types of rennet used in cheesemaking, each with its own characteristics:
| Type | Source | Suitable For | Pros | Cons |
|---|---|---|---|---|
| Animal Rennet | Stomachs of ruminant animals like calves, lambs, goats | Aged cheeses like cheddar, parmesan, swiss | Imparts complex flavors, preferred for aged cheeses | Not suitable for vegetarians |
| Microbial Rennet (Vegetable Rennet) | Fermentation of mold like Mucor miehei | Many cheeses, suitable for vegetarians | Vegetarian-friendly, consistent quality | May impart bitterness in aged cheeses |
| Chymosin Rennet | Genetically engineered chymosin enzyme | Many cheeses | Consistent quality, flavorless | Arguably not vegetarian as initial source is animal-derived |
| Vegetable Rennet | Plants like thistle, artichoke, nettle | Suitable for vegetarians and vegans | Vegan-friendly | Often imparts bitter, acidic flavors, not ideal for aged cheeses |
When and Why is Rennet Used?
Rennet is added during the cheesemaking process to coagulate the milk and separate the curds from the whey. This separation is crucial for creating the desired texture and flavor of the cheese.
The chymosin enzyme in rennet breaks down the casein proteins in milk, causing them to form a solid gel-like mass (curds) that can be separated from the liquid whey. Without rennet, it would be difficult to extract the milk solids effectively.
Cheeses Made with Rennet
Most aged and semi-hard cheeses are made using rennet, including:
- Cheddar
- Swiss
- Parmesan
- Gouda
- Provolone
- Manchego
- Pecorino Romano
Some fresh cheeses like paneer and queso blanco also use rennet for curd formation.
Summary
The most common types of rennet used for home cheesemaking are:
- Animal Rennet: Derived from ruminant stomachs, it is preferred for aged cheeses due to the complex flavors imparted by the various enzymes present. However, it is not suitable for vegetarians.
- Microbial Rennet (Vegetable Rennet): Produced by fermentation of the Mucor miehei mold, this is a vegetarian-friendly option. It is the most commonly used rennet, accounting for over 90% of commercial cheese production. The fermentation-produced chymosin (FPC) form is highly concentrated and flavorless.
While vegetable rennet from plants like thistle can be used, it often leads to bitterness, especially in aged cheeses. Chymosin rennet, though flavorless and consistent, is arguably not vegetarian since the initial chymosin source is animal-derived.
For home cheesemakers, animal rennet and microbial/vegetable rennet are the most popular choices, with animal rennet being preferred for aged cheeses and microbial rennet being a versatile vegetarian option suitable for most cheese varieties.
In summary, rennet is an essential ingredient in cheesemaking, responsible for separating curds from whey and enabling the creation of various cheese varieties. As a beginner, understanding the different types of rennet, when and why it’s used, and the cheeses it’s used for will help you navigate the cheesemaking process more effectively.