5 Things to Know About Microbial Rennet

by Paula Butler November 27, 2025

It takes more than just fresh, high-quality milk to make great cheese. One ingredient that isn’t in the spotlight but is responsible for causing the milk to separate into solid curds and liquid whey is the coagulating agent. That’s pretty important if you ask us!

Some cheeses are made through coagulation of milk by acidification. We always recommend using citric acid for this process and not lemon juice or vinegar because the latter two cause inconsistent results. Other cheeses are made through coagulation of milk by means of enzymes (rennet).

Let’s take a closer look at the second coagulating agent and, more specifically, microbial rennet. This ingredient is special because it is used to make very specific types of cheese as well as cheese that is safe for consumption by people with certain dietary restrictions.

Microbial rennet is one of several types of rennet

Cheesemakers can choose from animal-derived rennet (typically obtained from the inner stomach lining of a young calf, kid or lamb), microbial, vegetarian and FPC (Fermentation Produced Chymosin) rennet.

It is derived from microscopic organisms

Microbial rennet is NOT produced from animals. It is a coagulating agent derived from select species of yeast, fungi or mold grown in lab conditions where the living organisms can be strictly controlled and monitored. 

It produces halal-, vegetarian- and kosher-friendly cheese

Cheese produced from microbial rennet can be eaten by consumers whose diets restrict certain animal-based foods.

Since consumers do not need to worry if the animal from which the rennet is derived was prepared according to proper Islamic ritual, cheese made from microbial rennet is halal. However, those who eat halal should go the extra step and confirm that the cheese rind has been neither bathed in a wine or beer mixture nor treated with lard (pig fat).

Because no animals were harmed in the making of the rennet, the resulting cheese is vegetarian-friendly.

Lastly, cheese created using rennet that hasn’t been derived from an animal source is naturally kosher, which is a diet that places a restriction on eating dairy and meat together. 

Microbial rennet is less expensive than animal-derived rennet

Since microbial rennet can be mass produced in large batches of yeast, fungi or mold, it offers cheesemakers a more affordable alternative to animal-derived rennet.

It is better suited for young cheeses

Microbial rennet has a reputation for causing cheese to develop a bitter taste, particularly in types that require aging or ripening. Cheesemakers agree that this type of rennet is better reserved for younger or softer cheeses.

Still have questions? Learn more about microbial rennet here. 

Knowing which type of coagulant is used in your cheese gets you one step closer to perfectly transforming your milk into your favorite creamy, pungent, spreadable meltable cheese. Whichever method you choose, you can guarantee that a coagulant is part of anyone’s set of basic cheese making supplies because without it there is no cheese!

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