Nixtamalizing corn with ash involves simmering dried corn kernels in an alkaline ash-water solution, then soaking them for 8 to 12 hours until the outer hulls loosen and the interior turns translucent. The process transforms tough, dry kernels into soft, pliable nixtamal you can grind into masa for tortillas, tamales, or use whole in dishes like posole. It’s one of the oldest food preparation techniques in the Americas, and it works just as well today with a stockpot and a bag of hardwood ash.
Why Ash Works
Wood ash is highly alkaline. When you dissolve it in water, it creates a lye solution that does the same job as the more commonly referenced calcium hydroxide (pickling lime). This alkaline environment loosens the pericarp (the tough outer skin of each kernel), improves the corn’s texture and flavor, and unlocks niacin, a B vitamin that’s otherwise trapped in a form your body can’t absorb. Without this step, communities that relied heavily on corn as a staple historically developed pellagra, a serious niacin deficiency.
The process also substantially reduces mycotoxins, the harmful compounds produced by mold that can contaminate stored grain. Traditional nixtamalization lowers aflatoxin levels by 50 to 100 percent in the finished product, according to research published in the journal Toxins. Other common corn mycotoxins see similar reductions of 60 to 100 percent. This isn’t just a flavor technique. It’s a food safety one.
Choosing Your Ash
Not all ash is created equal. You want ash from clean-burning hardwood: oak, hickory, maple, and fruit woods all work well. Juniper ash is traditional in Navajo cooking and produces excellent results. You can also use ash from burned corn cobs, which some Indigenous traditions favor. The key requirement is that the wood was untreated. No lumber scraps, no painted wood, no charcoal briquettes with lighter fluid, and no softwoods like pine, which contain high levels of resin and produce inferior ash.
To prepare culinary ash, burn your hardwood down completely and let it cool. Sift the ash through a fine mesh strainer to remove any chunks of charcoal or unburned wood. What you want is the fine, powdery gray ash. Store it in a sealed container until you’re ready to use it.
Equipment You Need
Use a stainless steel, enamel-coated, or ceramic pot. Do not use aluminum. The lye in wood ash reacts aggressively with aluminum, producing hydrogen gas (which is flammable) and ruining the pot in the process. The Onondaga Nation’s cooking guidance specifically warns against aluminum cookware and utensils when working with ash. Use wooden or stainless steel spoons for stirring.
Beyond the pot, you’ll need a fine mesh strainer or cheesecloth for filtering the ash solution, a colander for rinsing, and a large bowl for soaking.
Step-by-Step Process
Make the Ash Water
For every pound of dried corn, stir roughly one cup of sifted hardwood ash into about two quarts of water. Bring this to a simmer and stir well, then strain the liquid through cheesecloth or a fine mesh strainer to remove the solid ash particles. You should be left with a yellowish, slippery-feeling liquid. That slippery texture tells you the solution is properly alkaline. If you’d rather skip straining, some traditional methods call for adding the ash directly to the cooking water with the corn and straining everything at the end, but pre-straining gives you a cleaner result and makes rinsing easier later.
Cook the Corn
Place your dried corn kernels in the pot and pour the strained ash water over them. The liquid should sit a couple of inches above the level of the corn. Cover the pot, bring it to a boil, then reduce to a steady simmer. Smaller kernel varieties typically need about an hour. Larger kernels, like heirloom blue bolita corn, can take up to an hour and a half.
Don’t watch the clock too closely. Watch the corn instead. You’re looking for two signs: the outer hulls should be visibly loosening and peeling away from the kernels, and when you cut a kernel in half with your thumbnail, more than half of the interior should look translucent rather than chalky white. If the centers are still opaque and starchy, keep simmering.
Soak Overnight
Once the kernels pass the translucency test, take the pot off the heat and let the corn sit in the cooking liquid for 8 to 12 hours. Most people simply cook in the evening and let it soak overnight. This extended soak finishes the chemical transformation, fully softening the kernels and completing the pericarp loosening that the boil started.
Rinse and Remove the Hulls
After soaking, pour the corn through a colander or strainer. If you cooked with unstrained ash, do this outside so you don’t clog your kitchen drain with ash sediment. Rinse the kernels under running water, working them between your hands. The hulls should feel floppy and almost slimy at this point. They’ll slip off easily as you rub the kernels together. Keep rinsing until the water runs mostly clear and the kernels no longer feel slick. Some people go through two or three rinse cycles. You don’t need to remove every last trace of hull, especially if you’re grinding the corn into masa, but you want the excess alkaline residue gone.
What you have now is nixtamal. The kernels will look swollen, feel tender, and smell distinctly earthy and corn-forward in a way that raw dried corn doesn’t.
What to Do With Your Nixtamal
Fresh nixtamal is versatile. For masa, grind the wet kernels through a grain mill or a heavy-duty food processor until you get a smooth, pliable dough. A traditional hand-cranked corn grinder (molino) or a metate works if you have one, but a food processor with a bit of added water handles the job. The masa should hold together when pressed without crumbling or sticking excessively. From there, you can press tortillas, form tamale dough, or shape pupusas.
For hominy or posole, skip the grinding. The whole nixtamal kernels go directly into soups and stews, where they’ll continue to soften and absorb flavor as they cook. Nixtamal keeps in the refrigerator for about three days, or you can freeze it for several months. Spread it on a sheet pan in a single layer to freeze, then transfer to bags so the kernels don’t clump into a solid block.
Troubleshooting Common Problems
If the hulls aren’t loosening after an hour of simmering, your ash solution likely isn’t alkaline enough. You can add more ash water (simmer and strain a fresh batch) directly to the pot and continue cooking. Different wood species produce ash with different alkalinity levels, so the ratio isn’t always exact on the first try.
If the corn tastes strongly chemical or soapy after rinsing, you’ve either used too much ash or haven’t rinsed thoroughly enough. A few more rinse cycles usually solve this. The finished nixtamal should taste clean, slightly mineral, and pleasantly corn-like.
Kernels that cook unevenly, with some turning mushy while others stay hard, usually point to old corn. Dried corn that’s been stored for years absorbs liquid at inconsistent rates. Starting with relatively fresh dried corn (within a year or two of harvest) gives the most uniform results.