Here are the potential areas for corn to get into coffee:

• Bean fermentation/processing: “Wet process” coffee introduces a ton of opportunities for corn-tamination, not the least of which being fermentation of the beans which could involve starter culture microbes that have been fed corn-derived sugar or possibly–and this is just a speculation as I don’t know the details– even some additional corn sugar to the beans to encourage the microbes to grow.  Additionally there are all kinds of machines and washes used along the way for wet processing that could introduce at least cross-contamination if not actual kernels of corn: A roaster I once emailed told me that they occasionally found kernels of corn in the roaster, presumably from the burlap bags the beans came in having been reused.
• Roasting: Corn-derived disinfectants, flavorings, or preservatives may be added to the beans before roasting. 
• Husking and Polishing: The beans are husked and may be polished on machinery to make them shiny. 
• Decaffeination: Chemicals used in the decaffeination process are corn-derived. There is a chemical-free process called the Swiss Water Process that isn’t really corn-safe even for the medium-sensitive, but it at least reduces the danger of cross contamination of the caffeinated coffee.
• Cross-contamination: Shared facilities/equipment with coffee that is chemically decaffeinated or flavored can contaminate the caffeinated/unflavored coffee beans. Additionally burlap bags are often re-used and you will sometimes find whole kernels of corn in with the coffee beans.  Roasting equipment and facilities may be cleaned with corny chemicals, or may be shared with other food items besides coffee.
• Brewing: Paper coffee filters will often be corntaminated, even the unbleached organic kind. Stick with reusable filters. Reusable filters could possibly be made from corny plastic or be impregnated with antimicrobials. The safest option is probably a stainless-and-glass french press.
• Packaging:  Paper coffee bags are usually lined with PLA , which is a plastic made from corn starch. Ingeo is a brand name for PLA. Foil bags can be dusted with corn starch or oiled with corn oil to keep them from sticking.

How to Find Safe Coffee

Here’s my approach:

1. Look for small coffee roasters who have single-origin coffees. This is both to avoid cross contamination  with things like flavored coffees and because they are more likely to be willing and able to answer questions.
2. Make sure they do not use PLA-lined or cornstarch-dusted bags, and that they do not use powdered (cornstarch-dusted) gloves in their facilities.

From there I honestly usually just trial carefully. Ideally they will have detailed reports on each variety with processing notes such as wet or dry process available on request or just published on theirs on their website, but I personally have not found that wet processing matters that much and have tolerated many wet-process coffees. However if I did react to a specific roast I would love having that info so I could guess at what the issue was. I think I’d have to like, be there and see them roasting to really know what would be an issue. Which is something I’ve been welcomed to do with local roasters, I just haven’t had time. I could definitely get way more into detail on what they do in their facilities after they get the green beans, but I honestly haven’t found that them answering every question I have right increases my chance to tolerate the coffee by much.

What I’ve found personally helps a lot with tolerating coffee I react to only very mildly is literally rinsing my beans in water and then dehydrating them after. This is probably a chemical sensitivity thing and may have more to do with my water issue than my corn allergy, and is also probably really an offensive idea to coffee snobs- myself included. But it’s the difference between being able to drink coffee safely or not, and I sure love coffee. I’ve not yet found a coffee that I *don’t* need to do this to, personally, and I’ve tried a lot of them.

Last edited March 9, 2021

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