Got Corn?

For a long time, I thought I was allergic to corn. Every time I ate anything with a corn product in it, my mouth and face would go numb and I would have other symptoms (read about it here). It wasn't until an allergist did an oral challenge with canned corn that I understood that the problem was not with the corn, but something being done to the corn. I began to research corn processing.

When corn is brought in from the field any number of things can happen: it can go straight to market, it can be canned, frozen, or processed into other products.

Fresh corn is not processed. Though fresh corn is not eaten raw, it is prohibited from sulfite exposure by federal law.

To make canned corn, the corn is removed from the cob, placed in a can with any other ingredients (water, salt, etc.) and then cooked while in the can. Nutrients can be lost in the cooking process and contamination can occur from the can lining; however, canning companies are not as worried about spoilage, thanks to the canning process, so the vegetables are usually not sulfited first. There are exceptions and other sulfited ingredients may be added, but for the most part, canned vegetables are sulfite-free.

For frozen corn, the corn is shucked and cut, treated with sulfites, and flash frozen. Because frozen vegetables are not intended to be eaten raw, sulfiting is allowed-- the sulfites prevent freezer burn from occurring as quickly.

But things get "fun" when it comes to processing corn...

First, the corn is soaked in water with added sulfur dioxide, which increases the yield from the corn. The corn can then be separated into oil, starch, fiber, and protein. The oil may be subjected to further sulfur dioxide or sulfites (usually only sulfur dioxide). The starches and other powder products are usually exposed to sulfites further on in the process. This aids in bleaching, preservation, and "flavor."

So, no, a sulfite sensitivity is not a corn allergy. On the flip side, any processed corn product will have been treated with liberal amounts of sulfites. Knowing which ingredients are made from corn can help you determine the amount of sulfite exposure in a product.

Here's a fairly thorough list.

More Information:
Sulfites: Separating Fact from Fiction
The Loss of Nutrients in Canned Vegetables
Bisphenol A: Toxic Plastics Chemical in Canned Food
Foods that may contain sulfites
List of Foods with Sulfites
Corn Wet Milling
Corn-free Foods
Corn Allergens

Image: Hess Design Works