Rennet Enzymes

Rennet Enzymes :

🧀 Rennet Enzymes: A Complete Guide

What Is Rennet?

Rennet is a collection of enzymes—mainly chymosin, but also pepsin and lipase—used to coagulate milk.
Its primary function is to turn liquid milk into curds (solids) and whey (liquid), which is the first essential step in making cheese.

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⭐ How Rennet Works

Rennet specifically acts on κ-casein, a protein that keeps milk in a liquid state.
When rennet breaks this protein down:

1. The milk proteins bond together

2. Curds form

3. Whey separates

This forms the base structure of cheeses like Cheddar, Parmesan, Gouda, Mozzarella, and many others.

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🧪 Types of Rennet

1. Animal Rennet

• Extracted from the abomasum (fourth stomach) of unweaned calves, lambs, or kids

• High in chymosin (80–95%), giving excellent curd formation

• Preferred for traditional hard cheeses (e.g., Parmigiano Reggiano)

Properties:
✔ Strong enzyme activity
✔ Consistent, clean flavor development
✔ Historically used for centuries

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2. Microbial Rennet

• Produced from molds like Rhizomucor miehei

• Suitable for vegetarians

• Often used in industrial cheesemaking

Pros:
✔ Cheaper
✔ Vegetarian
Cons:
✖ Can create slight bitterness in long-aged cheeses

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3. Fermentation-Produced Chymosin (FPC)

• The most common rennet today

• Made by inserting the calf chymosin gene into microbes (like yeast), which then produce pure chymosin

• Fully vegetarian

• Extremely consistent—used in 90%+ commercial cheeses

Benefits:
✔ High purity
✔ Predictable performance
✔ No off-flavors
✔ Halal & kosher versions widely available

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4. Vegetable Rennet

Derived from plants with coagulating properties:

• Thistle (cardoon)

• Nettle

• Fig sap

• Mallow

Used mostly in traditional Mediterranean cheeses like Torta del Casar.

Flavor:
Produces soft, creamy textures with a slightly herbal or bitter complexity.

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🧀 Forms of Rennet

Rennet comes in several formats depending on your use:

• Liquid rennet

Most common for home cheesemaking
Fast and easy to measure

• Tablet rennet

Shelf-stable, convenient

• Powdered rennet

High concentration; used commercially

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📏 Using Rennet (Home Cheesemaking)

A typical dosage for milk:

• Liquid rennet: 1/4–1/2 teaspoon per 4 liters (1 gallon) milk

• Tablet rennet: 1/4–1/2 tablet per 4 liters

Always dilute rennet in non-chlorinated water before adding to milk.

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🍕 Which Cheeses Use Rennet?

Most non-acid-coagulated cheeses require rennet, including:

• Cheddar

• Mozzarella

• Gouda

• Parmesan

• Swiss

• Blue cheeses

• Brie & Camembert

Cheeses not requiring rennet (acid-based):

• Ricotta

• Paneer

• Queso fresco

• Mascarpone

• Cottage cheese (some versions)

OTHER SOURCES

Cheese Rennet
* Some cheesemakers continue to make and use rennet in this way; the vast majority use commercially processed rennet, which is made by creating a slurry and then subjecting it to a compound which will cause the enzymes to precipitate out. The main enzyme in rennet is rennin, although there are a few other enzymes as well, and the precise content depends on the animal the rennet comes from; sheep rennet, for example, is different from cow rennet.
* Before the rennet can be added to a recipe, it must be dissolved in cool water; dissolution is critical for the rennet to work. One important thing to know when working with rennet tablets is that high heat will deactivate the enzymes, which is why cool water is required for dissolution, and why temperature control of the milk used for cheese, junket, and other foods which call for rennet is very important.
Cheese Rennet VIDEO