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 cheeses made in the United States, and in much of the West, use a genetically engineered protein that is made from genetically engineered yeast and bacteria. 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.'
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
- "I Grow GMO: Not Ashamed or Embarrassed," Foodie Farmer
- "Hawaii papaya growers proud of GM Hawaiian papayas," Packer
- "Superior strawberries: How genetics can bring flavor back to the big red berry," Genetic Literacy Project