Cheese is actually a difficult prospect for many folks with corn allergies. In fact, I’ve had some of my most surprising severe reactions from cheese. It seems like such a simple product, and I’ve had a few cheeses that nearly sent me to the hospital from just one bite!

I don’t know if I have the whole story here, but here are potential corn allergy issues I’ve identified with cheeses:

• Production: -corn starch dusting mold and I think also sanitizers which are almost always corn based used on equipment.
• Packaging: Plastic wraps dusted in corn starch, wax papers waxed with corn-based wax or dusted with corn starch. For rounds that are coated in wax, the wax itself could be corn based or could contain a dye that is corn based.
• Re-packaging. When cheese shops and grocery store cheese counters cut the wheels and repackage slices, their equipment may be cross contaminated with corn products, the cleaner on it is cleaned with a corn based sanitizer, and the plastic wrap itself is often dusted in corn starch.
• Starter cultures, rennet, and enzymes. The Wikipedia entry on Rennet has a good overview of what rennet is and how it is produced.  There are 5 types of coagulants in cheese making:
  • Animal Rennet: Enzymes that coagulate cheese are harvested from the stomachs of calves. While this is a problem for vegetarians, it is one of the safer cultures in cheesemaking for a corn allergy. However that doesn’t mean it’s always safe. Animal rennet can contain all kinds of preservatives that are commonly derived from corn. This ingredients list for a liquid animal rennet contains: propylene glycol, caramel color, flavor, sodium benzoate, potassium sorbate, all of which are likely from corn. So the safety of the cheese will just depend on the source of the rennet.
  • Vegetable Rennet: Many plants produce coagulating chemicals. This can be a variety of sources from caper leaves and thistles to phytic acid from soybeans, and yes, probably corn. I can’t find any evidence that coagulating chemicals are ever extracted from corn, just guessing. However even if they aren’t, the same preservatives listed above are often included in the vegetable rennet packaged for resale. Here’s one ingredients list that includes acetic acid and sodium acetate.
  • Microbial Rennet: Molds that produce coagulating enzymes are cultured to produce the coagulants. Can be cultured on a corn sugar medium and of course can be preserved with corn-based chemicals similar to animal rennet.
  • Fermentation-produced Chymosin. This is a genetically engineered product. Rennet producing genes are extracted from animal stomachs and inserted into various bacteria, fungi, and yeasts to make them produce chymosin when they wouldn’t normally. Then the chymosis is produced similar to microbial rennet, via fermentation, probably on a corn sugar medium.
• Dyes. Many cheeses are colored with anatto, which can be from corn, or another dye that is corn-based.

So How Do I Find Safe Cheese?

For me personally, I find that artisan cheeses imported from cheese-loving european cultures such as France are better bets. I really don’t know the details of why that’s true, but I am guessing all of the possibilites for “incidental corn” listed above are just lower in those cultures due to small-batch and traditional practices. I have found a couple american-made cheeses that are okay, but the percentage is very small and often they worked for only a time before something changed and I started reacting. The problem is that corn-based chemicals are so widely available here for so many things that eventually the suppliers upstream of the cheese producers will change and previously safe food will become corny.
Something else I am finding is that I have to buy whole rounds.. when big grocery store counters cut the wheels and repackage, their equipment is not just cross contaminated, but also the cleaner on it is cleaned with a corn based sanitizer, and the plastic wrap itself is often dusted in corn starch. I could work with a small shop to cut me a fresh piece from a wheel using equipment cleaned with safe cleaners, but I just haven’t taken the time, instead buying products that come from the manufacturer individually packaged. Provided that the original packaging is safe of course.