AFTER READING BRUCE BRADLEY’S POST ABOUT tricks of the food industry trade, I promptly freaked out over the fact that I’d been eating calf stomach – rennet – in my cheese. After maniacally checking the labels of all the cheese in the house, I calmed down enough to turn to my best defense when I’m faced with a food crisis – looking for answers.
Rennet is a complex of enzymes found in the stomach of baby mammals that allows them to process mother’s milk. According to Wikipedia, the active enzyme in rennet is called chymosin or rennin but there are also other important enzymes in it such as pepsin and lipase.It is used in cheese makingto speed coagulation and separate the curds and whey after the starter culture is added to the milk.
There are different types of rennet:Animal rennet comes from the stomach of newborn calves, lambs, and kids (the baby goat kind, people, don’t freak out.) The enzymes needed are only found in the fourth stomach of the ruminants before they are weaned. For cheese making, rennet from the animal providing the milk is used (calf rennet for cow’s milk cheese for example.)There is a traditional way to get animal rennet, which involves combining the stomach of the animal with salt water or whey along with wine or vinegar. Some traditional cheese makers in Europe still use this method.
Then there is the modern way to get animal rennet involving deep frozen stomachs, enzyme-extracting solutions, and stomach acid. Interestingly, there could be trace amounts of Sodium Benzoate in rennet produced this way.
Animal rennet can also be genetically engineered by inserting cow DNA into certain bacteria, fungi, and yeasts – no baby animals harmed. According to Wikipedia, genetically engineered rennet has about 80% of the market share and as of 2008 â€œapproximately 80% to 90% of commercially made cheeses in the US and Britain were made using GM-based rennet.
Vegetable rennet can be made from a variety of plant sources such as fig, thistle, safflower, and dried caper leaves. It can also be made from genetically modified soybeans. Since there is no worldwide industrial production of vegetable rennet, it is often made from microbial sources.
Microbial rennet is made from molds (although there is no mold in it.)
SHOULD I EAT IT?
Well, that all depends on what your concerns are.
If you are vegetarian, then avoid any cheese with rennet, animal rennet, or enzymes (which typically means animal rennet, although not always, but there’s no easy way to know) listed in the ingredients. Vegetable rennet will be listed as such, same with microbial rennet.
If you try to avoid GMOs, well, it’s a little tougher. Organic cheeses won’t have GMOs. But since genetically engineered rennet doesn’t have to be labelled, you have no way of knowing whether the rennet is genetically engineered or if the vegetable rennet comes from GMO soybeans. Stick with microbial rennet cheeses, traditionally produced cheeses, or organic cheeses.
With regard to GMOs: the cows, sheep, or goats are being fed GMO corn or grain will also have an impact on the overall GMO-ness of the cheese. There is just no good way to know unless you buy organic.
If you are concerned about baby animals being killed for rennet, stick with cheeses using vegetable or microbial rennet sources. Although remember, 80% of the rennet is genetically engineered without the use of baby animals.
If you are lucky enough to live near a Trader Joes, they have thoughtfully provided this informative web page detailing which of their cheeses contain which kind of rennet. (Remember, it doesn’t tell you anything about GMOs.)