Slammed by critics, Chipotle has been forced to
back track on its non GMO claims. Its beef, pork and chicken are
sourced from farm animals fed with GMO grain. And all of its
calorie-packed sodas are sweetened with GMO sugar.
But it has yet to come clean on its most controversial GMO
ingredient: all of its cheese is genetically modified. That’s right. The
clotting agent used to curdle the milk into cheese is genetically
engineered. So much for Chipotle’s bragging claim of transparency.
In fact, almost all the hard cheese made in the United States, and in much of the West, uses a genetically
engineered protein that is made from genetically engineered yeast and
bacteria to make cheese. That includes cheese made in Vermont, which has
passed a mandatory GMO labeling bill–that curiously exempts its iconic
Vermont cheese from carrying a GMO label. So much for the consumer’s
‘right to know.’
In fact, critics of GMOs almost never acknowledge the fact that almost all hard cheeses are GMOs. In cheese production,
coagulants called rennet are used to clot milk. The primary enzyme in
rennet driving the clotting process is called chymosin, which acts on
milk proteins like casein and makes milk curdle.
Traditionally, rennet is obtained from the fourth stomach
lining of an unweaned calf. Calves have a higher amount of rennet in
their stomachs compared to adults as they use it to digest milk, their
main source of food. The rennet extracted from the stomach linings is
usually a mixture of chymosin, pepsin (another enzyme) and other
proteins.
Beginning in the 1960s, the price of rennet, a byproduct of the veal industry, rose and became less stable
as the animal rights movement grew. Demand for cheese also soared, and
cheese-makers began looking for alternative sources of rennet from
plants and microbes.
Some plants and microbes naturally produce enzymes that
have coagulating properties like rennet. However, rennet from these
sources tend to produce other side reactions in cheese production, leading to undesirable results in taste.
So how did biotechnology come to play a role? In the late
1980s, scientists figured out how to transfer a single gene from bovine
cells that codes for chymosin into microbes, giving microbes the ability
to produce chymosin. These genetically modified microbes are allowed to
multiply and cultivated in a fermentation process while they produce
and release chymosin into the culture liquid. The chymosin can then be
separated and purified. Chymosin produced using this method is termed
fermentation-produced chymosin, or FPC.
FPC was given
Generally Regarded As Safe (GRAS) status by the Food and Drug
Administration in 1990 after 28 months of review. The FDA found that FPC
was substantially equivalent to rennet produced from calves, thus it
needed no special labeling or indication of its source or method of
production. FPC is actually more pure than calf rennet, as it does not
contain other proteins from the calf stomach lining that cannot be
separated from calf rennet during production. “The real advantage is
that it is probably a much cheaper way of producing this substance than
to grow calves,” said William Grigg, an FDA employee.
Today ninety percent of the cheese in the United States is
made using FPC. In the past two decades, FPC has been considered the
ideal milk-clotting enzyme. FPC has been regarded as suitable for
meeting vegetarian, kosher and halal requirements. However, some
vegetarians consider FPC to be derived from animals as the microbes were
genetically modified using bovine genetic material. In response,
scientists began synthesizing the gene needed to produce a synthetic
form of FPC that does not have any genetic material from animals.
GMO concerns about FPC are few compared
to those directed at genetically modified crops. Recent campaigns in
Vermont, a major cheese-producing state that just passed a GMO-labeling
law did not address the use of FPC to make cheese; dairy products are
simply exempt. FPC is not allowed
in organic cheese based on the certification rules in the United
States, Europe and Canada, providing an option for consumers who wish to
avoid FPC.
FPC is an important but little-known success of
biotechnology. Cheese-makers still use animal rennet, but to a large
extent, FPC has removed the need for animal rennet in the production of
cheese.
Jon Entine, executive director of the Genetic Literacy Project, is a senior fellow at the World Food Center Institute for Food and Agricultural Literacy, University of California, Davis. Follow @JonEntine on Twitter
