Spring is here, and for those who need to avoid grocery store produce due to sprays and cross contamination, that means food preserving. I have done a little bit of canning, but I’m no expert: I’m here to talk about avoiding corn in canning supplies. If you have questions about how to actually do the canning safely or how to make your canned goods taste *good*, that is a question for someone else.
Avoiding Corn in Canning
Lids & Jars
The standard glass canning jars available in the grocery store are perfectly safe for a corn allergy. Rather, it’s lids are the single biggest concern for corn allergy in canning. The new Ball BPA-free lids are NOT corn free. I don’t think anyone has been able to get a detailed answer from Ball about what exactly is in the resin, but something in it is causing many corn allergics to react, and NOT just the most sensitive folks. Some are even breaking out in a rash from touching the lids. I had thought for a time I was okay with them because I was able to store non-canned food in them. Turns out that the resin in the seal was simply staying on the lid and not touching the food. Once I water-bath canned dozens of quarts of (expensive, mail-order) mandarin oranges, I discovered that when the boiling water melts the resin and creates a seal, it also infuses all of the water with corn. My non-allergic friends and family have been enjoying my delicious, now-corny mandarins all winter.
One possible option other than the Ball canning lids is Tattler reusable canning lids.
I’ve been using the Tattlers and so far, so good, but I’ve done basically two batches of applesauce so far and not much else. Updated August 2015: Yeaaahh I think I had a mild reaction to applesauce canned with the old school tattler lids. On top of that, right after I bought a bunch of them they changed their lids to be “new and improved” and have a better seal. No definitive reports on safety.
Another alternative is to use the Weck canning system. These are reported safe by several corn allergics. I haven’t tried them quite simply because they are expensive. The seals on the Weck jars are natural latex rubber, so NOT safe for a latex allergy.
There are a couple other kinds of canning lids, but I don’t know anything about them. If you have some options and links and contact info to the companies, please comment below.
As always, any ingredients you use in canning need to be safe for you. Application of heat can denature some allergens for some people, but so far I haven’t heard of anyone with a corn allergy being able to eat corn just because it had been cooked enough. Here are the biggest concerns with canning:
Salt can most definitely be corny, so use something that you know is safe for you. Any safe salt should work fine instead of “canning salt.” The main reason to use canning or pickling salt is that it will not have minerals which may alter the appearance (but not taste or safety) of your canned items.
Sugar can be cross contaminated with corn. Make sure to use something you know is safe for you.
Lemon Juice or Vinegar
Botulism requires an anaerobic (no air) environment and low acidity to grow. Adding an acid is a common way of making a low-acid food item such as a vegetable or some varieties of tomatoes safe for water-bath canning. Both pre-squeezed lemon juice and vinegar are commonly corntaminated. In the case of vinegar, it’s actually typically made *from* corn. There are vinegars that are not made from corn, though many of them are contaminated in some way. If you have a safe premade vinegar, great. Do NOT use your own homemade vinegar though, unless you have a way to be 100% sure that it is ph 4.5 or below. Similarly, the FDA’s official recommendation on lemon juice is to only use the bottled stuff because it has a standardized acidity. Of course this standardized acidity can be achieved by adding corn-derived acids, so that is no good for us. If you have a bottled lemon juice that works for you, great.
If you don’t have safe vinegar or lemon juice, probably skip these recipes and convert them to pressure canned recipes instead, which do not require a high acidity since the high heat of the pressure canner will kill all botulinum spores.
General Canning Resources
If you are new to canning, I recommend that you read up on canning safety. Even if you have some basic familiarity, you may want to review. Safety recommendations have changed in the last decade or two, so what you learned from your grandmother may not be safe. Botulism is a real concern with canned goods, even today, so it is important to follow temperature, acidity, and cook time guidelines in well-tested recipes. The below resources can teach you about canning in general, but be aware that the recommended ingredients may not be safe for you.