How is vegetarian rennet made?

In this brief guide, we will answer the query, ‘How is vegetarian rennet made?’ and will discuss a different type of vegetarian rennet.

How is vegetarian rennet made?

Vegetarian rennet is made in different ways. Vegetarian rennet can be made from plant extract, from microbial extracts, and even genetically engineered rennet can be used in vegetarian cheese making.

A non-animal substance called vegetarian rennet is used in the coagulation process of vegetarian cheeses instead of animal rennet. The rennet in certain cheeses is obtained from the stomachs of calves, however, vegetarian cheeses are available as well

The current world cheese production is about 19×106 t per year, representing approximately 35% of total milk produced. Around 75% of this production and the majority of cheese varieties are produced by enzymatic (rennet) coagulation, which are suitable for vegetarians as well for vegans (3).

What is rennet?

The most widely used milk clotting enzyme in the cheese industry is calf rennet, which is mainly obtained from the fourth stomach of suckling calves. Calf rennet has a high milk casein activity/ proteolytic activity ratio and high heat sensitivity, which is the ideal clotting enzyme, leading to great cheese yield and better textural and sensorial properties of cheese and a major reduction in bitterness. Calf rennet was the earliest milk clotting enzyme used for cheese making, and this enzyme is also known for its high specificity for cleaving caseinomacropeptide from κ-casein. Recently, some plant-derived, microbial rennets, recombinant and microbial ascalf rennet substitutes have been discovered and industrially produced (1). Therefore, it is necessary to investigate the source of the rennet used by one cheese producer.  

We must first study the component rennet and why vegetarians should avoid foods containing this ingredient. Cheese is made by adding rennet to the milk. This may seem to be innocuous, but it isn’t. Chymosin, the major enzyme in rennet, is extracted from the lining of a newborn calf’s fourth stomach. The enzyme is created in this area to aid in the digestion of milk for newborn cows. Rennet is also used in the digestion process by piglets as a supplemental source of rennet This enzyme is clearly in need of a vegetarian alternative. Since animal rights groups have protested the methods of the veal business, animal rennet is becoming more difficult to get.

How Vegetarian Rennet Is Produced?

In the same way, as “normal” rennet coagulates proteins in milk to form cheese, vegetarian rennet does the same thing. Vegetarian rennet, on the other hand, is derived from plants or microorganisms.

·         Vegetable Rennet

Vegetable rennet is made by harvesting enzymes from plant sources. This rennet is vegetarian. Among them are the following:

·         Leafy figs.

·         Melons

·         Native wild thistles are safflower.

. Chymopapain, from papaya fruit

. rennet from ginger

However, most of these milk clotting enzymes have low efficiency of purification because of the cellulose, which is difficult to separate and remove. Although some of them, extracted from small plants, show high activity, they exhibit weak heat sensitivity. Most plant-derived rennets typically exhibit low milk clotting activity/ protein activity ratios resulting in poor cheese yield and formation of bitter substances during cheese ripening (1).

·         Rennet from microbes

Enzymes from fungus or bacteria are harvested and fermented to produce microbial rennet. To avoid a bitter aftertaste, this form of rennet is normally used solely for manufacturing cheeses that are not matured for a lengthy period. Vegetarians may use this form of rennet as well.

Microorganisms have the advantages of a short growth cycle, easy fermentation, and are not limited by space and region of production. However, it is found that most microbial rennets have high proteolytic activities and low milk clotting activity/ proteolytic activity ratios leading to low cheese yield and bitterness. Only a few microbial rennets are suitable for cheese production (1).

·         Biotechnologically Modified Rennet

Fermentation Produced Chymosin (FPC).  is the third form of rennet that is deemed vegetarian Calves’ DNA is used to extract a gene, which is then inserted into the DNA of yeast, mold, or bacteria to create this product. That signifies that FPC is a GMO product. This sort of rennet is used to make the majority of cheese in the United States. The FDA authorized the use of this rennet in cheese in 1990.

Enzymes called “vegetarian rennet” in many instances are made using genetically modified rennet. Chymosin DNA is extracted from a calf’s stomach cells and modified in this example. However, this isn’t always the case with enzymes that have been synthesized. In certain cases, they may also be made without the use of animal cells. The cDNA without intron is used as template for transcription and translation and the structure of the recombinant rennet is similar to that of the original rennet (1). The most important thing is to verify with the manufacturer to find out which brands are safe to purchase. You won’t see the sort of rennet used to produce the cheese listed on the label.

The amount of cheese produced by fermented milk clotting enzymes in the United States and the United Kingdom comprises 70% and 90% of the total cheese production, respectively. Recombinant Lactobacillus kefiranofaciens sub sp. milk clotting enzymes (Gist Brocades), Aspergillus Niger MCE (Genencor) and E. coli K-12 MCE (Pfizer) show good characteristics in cheese production. The advantages of fermented produced rennets in protein hydrolysis, cheese yield, texture and flavor make it a potential calf rennet substitute (1).

Checking for Vegetarian Rennet in Cheese: What to Look for?

The Food and Drug Administration does not require cheesemakers to disclose the kind of rennet used in their products. On cheese labels, rennet manufactured from animal Chymosin is often referred to as “conventional rennet,” while most cheesemakers who utilize plant-based rennet mention “thistle rennet,” “plant rennet,” or “vegetarian rennet.”. Using plant-based rennet is something that cheesemakers are likely to put prominently on their products if it’s worth the additional effort.

The best option is to go to a cheese store with experienced cheesemongers and purchase your cheese there. If they can identify all of the cheeses in the shop that are not manufactured with animal rennet, then they are doing a good job.

According to the USDA, in the United States, microbial rennet and fermentation-produced chymosin are now more widely used in cheese making than animal-derived rennet. Approximately 70 percent of all cheese is produced with fermentation produced chymosin, while approximately 25 percent is made with microbial coagulants, and the remaining 5 percent is made from calf rennet (2).

Hidden facts about vegetarian cheese

A vegetarian cheese made using the FPC rennet, which contains DNA extracted from the calf’s stomach cells, is the real deal, since you may be eating it. Although most of the enzyme is removed from the whey, for most vegetarians, this makes a difference and is worth a little investigation’s

When you’re eating cheese, you want to know where the rennet used to make it came from. The only way to know for sure what kind of rennet is used in the cheeses is to contact the maker and inquire. The FDA defines “enzymes” as “animal, vegetable, or microbial rennet,” however most labels simply mention “enzymes” as an ingredient. Enzymes are natural protein molecules that act as highly efficient catalysts in biochemical reactions. They are used to carry out naturally occurring biological processes that are useful in the processing of food products or ingredients (2). Most cheese labels include the phrase “rennet and/or additional clotting enzymes of animal, plant, or microbial origin” to describe clotting enzymes. 

The requirements provided by the FDA for specific standardized food products containing animal-derived rennet are provided in Code of Federal Regulations. The requirements provide descriptions of each dairy product (e.g., sour cream contains no less than 14.4% milk fat an acidity of at least 0.5%), allowed optional ingredients (e.g., vitamins, salt, and rennet), and labeling requirements including the name(s) allowed on product labels (2).

Vegetarian rennet should be purchased from marketplaces that recognize the distinction and are prepared to reveal the source. As an alternative, you might check for vegan cheeses.

Other FAQs about Vegetarian that you may be interested in.

Is calcimax vegetarian?

Is caldikind plus vegetarian?

Is Celin 500 vegetarian?

Can you be vegetarian and pregnant?


In this brief guide, we answered the query, ‘How is vegetarian rennet made?’ and discussed different types of vegetarian rennet.


  1. Liu, Xiaofeng, et al. Advances in research on calf rennet substitutes and their effects on cheese quality. Food Res Int, 2021, 149, 110704.
  2. Enzymes Animal Technical Report 2011.  Agricultural Marketing Service. USDA.
  3. Almeida, C.M., Simões, I. Cardoon-based rennets for cheese production. Appl Microbiol Biotechnol, 2018, 102, 4675–4686.