Genetically Modified Microbial Rennet: How Vegetarian Is It?

Jeanne Yacoubou, MS

Vegetarian Resource Group recently received an email inquiry from a food
scientist. She asked:

genetically engineered microbial rennet considered vegetarian?…My question is
not just whether the genetically engineered microbial rennet is vegetarian, but
this rennet is added to milk to make cheese, and in the cheese-making process,
whey is produced, and this whey is concentrated to make whey protein isolate. I
would like to know if this end product “whey protein isolate” is
considered vegetarian due to the use of genetically engineered microbial rennet
in the manufacturing process.”

is how we responded in August 2021:

you seen an article we did in 2012 on microbial rennets and fermentation
produced chymosin (FPC)? In that piece, we describe the bioengineering involved.
We point out exactly where and when the genetic code for an animal’s enzyme
(specifically a bovine calf’s) comes into play to produce the active component
of rennet known as chymosin. It is chymosin that does the actual work of
curdling cow’s milk during dairy cheese making.

speaking with enzyme company experts, I personally do not believe
bovine-derived, bioengineered chymosin is vegetarian.

some point long ago, the genetic material encoding for bovine chymosin was
removed from an animal. This could have happened when rennet-containing
material or cells from a calf’s stomach were removed from the animal. Patent
applications describe animal glands from a slaughterhouse as the source of the
genetic material. In any case, we know that the original process was never
animal-free. The goal was to extract and isolate the genetic code for the
cheese-producing enzyme. This process is a form of bioengineering that produces
a genetically modified organism (GMO).

manufacture today, many generations of microbes later, depends on that first
bovine. The gene encoding for bovine chymosin directs the microbes to produce
bovine chymosin each and every time, even today.

don’t distinguish the two enzymes as (1) non-vegetarian originally, but (2)
transformed into being vegetarian many microbial generations later after (or
because of) genetic bioengineering and microbial fermentation. The genetic code
used, in both cases, is bovine.

is true that once the genetic material was removed from animal rennet, cells in
the calf’s stomach lining, or from the animal’s glands, no more animals were
needed. Animals aren’t used to make each batch of enzyme. Researchers extracted
the genetic blueprint from one animal/animal organ and made copies of it in the
lab via and in microbes.

this basis, many vegetarians and cheese companies using FPC produced in this
manner consider cheese made with it as “vegetarian.” (They also
consider it “non-GMO.”) Possibly, they do not consider animal genes as “animal
products” or “animal-derived ingredients.” The presence of animal ingredients
would make their product non-vegetarian. No calf is used to make each fresh
batch of enzymes, either. So, they assert, bovine FPC must be vegetarian.

a result, you’ll find “vegetarian rennet” or “vegetarian enzymes” on
dairy cheese labels.

described in our 2012 article linked to above, due to technological advances in
food science, there are cheese-producing enzymes originally formed from the
encoding of genetic material (modified or not) belonging to a microbial
species and inserted into organisms of a different microbial species to
yield chymosin after fermentation.

enzymes are truly bioengineered “microbial enzymes” in every sense of that
term, known as FPC.

this biotechnological discovery was found through experimentation to yield
greater amounts of chymosin, or a type of chymosin that leads to better-tasting
cheese. Maybe it was less expensive to manufacture.

whatever reason, I would call it “vegetarian rennet.” I don’t know if or how
much of these 100% authentically microbial chymosins exist today or, if they
do, what their market share is as compared to the bovine FPC.

any case, 90%+ of all dairy cheese in the United States is made with some type
of FPC.

type of FPC? Although The VRG has not done research this year on FPC, we
suspect that it is largely bovine chymosin produced through bioengineering as
described initially in this article that’s widely used today to make dairy

Rennet or FPC in Whey

The VRG reported in 2008, 90-95%
of the small quantity of milk-curdling enzyme used to make a batch of cheese
remains in the whey during dairy cheese making.

to answer the second part of our inquirer’s question concerning the vegetarian
status of whey protein isolate, the argument given above directly applies here
as well.

my view, whey and similar products derived from dairy cheese making using
bovine FPC are not vegetarian. This is not the view shared by many vegetarians
or by food and beverage companies selling products containing whey or related

if a type of FPC that is completely free from all animal products, including
animal genes at any and all points during the development of the FPC from its
first creation until now, is used to make cheese, then I would describe both
the enzyme and the cheese formed from it as vegetarian. Similarly, the whey and
whey-containing products formed during that FPC’s use in cheese making
would also be vegetarian.

VRG recommendation to companies regarding FPC and labeling of cheese
and whey-containing products

VRG recommends that all companies using FPC to make dairy cheese, whey, whey
protein isolate, or products containing them specify on their labels and on
their websites how their FPC was made. Then consumers will have all the
information they need to determine if a product is right for them, whatever
their dietary preference. They may even decide to choose vegan cheese

specifically, if their FPC resulted from the laboratory engineering of a calf’s
genetic material many microbial generations ago and inserted into a microbe’s
genetic makeup, then state it as such. If their FPC came from a uniquely microbial
transfer of microbial genetic information only, with no animal
genetic inputs ever, even at the beginning, then this should be so stated.

readers who have any further questions about FPC and its use in cheese or
whey-containing foods and beverages should contact food companies directly.
They, in turn, should contact their ingredient suppliers and hopefully relay
source information back to you. For tips on how to ask questions in order to
maximize your chance of receiving accurate information from food companies,
this VRG article may be helpful.

more ingredient information, see

contents of this posting, our website, and our other publications, including
Vegetarian Journal, are not intended to provide personal medical advice.
Medical advice should be obtained from a qualified health professional. We
often depend on product and ingredient information from company statements. It
is impossible to be 100% sure about a statement, info can change, people have
different views, and mistakes can be made. Please use your best judgment about
whether a product is suitable for you. To be sure, do further research or
confirmation on your own.