Nixtamalizing corn means cooking and soaking dried corn kernels in an alkaline solution, typically water mixed with food-grade lime (calcium hydroxide), then washing and grinding them into masa. The standard ratio is 1 part corn to 3 parts water by volume, with 1 to 2 percent lime by weight of the corn. The whole process takes roughly 12 to 14 hours, most of it hands-off soaking time.
What You Need
The ingredient list is short: dried whole corn kernels, food-grade calcium hydroxide (sold as “cal” in Mexican grocery stores or as pickling lime in hardware-oriented stores), and water. For one pound of dried corn, you’ll use about 6 cups of water and 1 to 2 tablespoons of calcium hydroxide. You also need a large non-reactive pot (stainless steel or enamel), a colander, and something to grind with, whether that’s a traditional stone metate, a hand-cranked corn grinder, or a food processor.
Choose your corn carefully. Dent corn varieties with a high proportion of soft starch produce the most tender, pliable tortillas. The elite tortilla corns grown in Mexico are dents with soft, starchy interiors. Flour corn also works well for masa. Flint corn, with its hard, glassy endosperm, is better suited for dishes like polenta or posole where you want the kernels to hold their shape. If you’re making tortillas, look for dent or flour types. Standard dried field corn from a feed store works in a pinch, but specialty varieties bred for masa will give noticeably better flavor and texture.
Cooking the Corn
Dissolve the calcium hydroxide in your water first, stirring until the powder is fully incorporated. The water will turn milky. Add the dried corn and bring the pot to a low boil, then reduce to a gentle simmer. Cook for 30 to 45 minutes, stirring occasionally. You’re looking for the outer skin of the kernels (the pericarp) to loosen and the corn to soften without becoming mushy. A kernel should dent when you press it with a fingernail but still feel firm in the center.
More lime and longer cooking times produce softer, more digestible results, but going too far makes the masa gummy and gives it a harsh, soapy taste. If you’re new to this, start with 1 percent lime (about 1 tablespoon per pound of corn) and 30 minutes of cooking. You can increase next time if the pericarp doesn’t loosen easily.
The Overnight Steep
Once the corn is cooked, remove the pot from heat and let it sit, covered, at room temperature. This steeping phase is where most of the transformation happens. The alkaline water continues to break down the pericarp and the waxy outer layer of each kernel, dissolving the hemicellulose that holds the skin in place and creating pores that let water penetrate deep into the starch. A standard steep is 8 to 12 hours, or simply overnight.
Shorter steeps of 3 to 5 hours can work for softer corn varieties, but 12 hours gives the most consistent results for home cooks. The corn will swell noticeably and the cooking liquid will turn yellow or orange, depending on the corn variety. This liquid, called nejayote, is strongly alkaline and full of dissolved pericarp, waxes, and pigments.
Washing the Nixtamal
Drain the nejayote and transfer the corn to a colander. Rinse it thoroughly under running water while rubbing the kernels between your hands. The loosened pericarp will slough off as a slippery, mucilage-like coating. How aggressively you wash matters. More washing removes more of the alkaline flavor and produces a cleaner-tasting, lighter-colored masa. Less washing leaves some of that distinctive mineral tang and a slightly yellow hue, which some cooks prefer for flavor.
The washing step also has a food safety benefit. Cooking, steeping, and washing together are what drive the reduction of naturally occurring mold toxins called aflatoxins. The full process, from raw corn through finished tortilla, reduces aflatoxin levels by 50 to 90 percent or more compared to untreated corn. The combination of alkaline breakdown and physical rinsing is key; skipping the wash step significantly reduces this benefit.
Once washed, the kernels are called nixtamal. At this point you can refrigerate them for a day or two, or freeze them for longer storage.
Grinding Into Masa
Wet-grind the nixtamal into a smooth dough. A hand-cranked corn grinder (often sold as a “corona mill”) is the most accessible home tool for this. Run the nixtamal through twice: once on a coarse setting to break the kernels apart, then again on a finer setting to develop a smooth, cohesive dough. A food processor works in a pinch but tends to produce a slightly gummier texture because it shears the starch differently than a mill does.
The masa should feel like soft playdough, holding its shape when squeezed but not cracking at the edges. If it cracks, it’s too dry; knead in a small amount of water, a tablespoon at a time. If it sticks to everything, it’s too wet; let it rest uncovered for 15 to 20 minutes so some moisture evaporates. Fresh masa is best used the same day, but it keeps in the fridge, tightly wrapped, for two to three days.
Why Nixtamalization Matters Nutritionally
This process isn’t just about texture. Untreated corn locks up most of its niacin (vitamin B3) in a form the human body can’t absorb. Populations that historically relied on corn as a staple without nixtamalizing it developed pellagra, a serious B3 deficiency disease. The alkaline treatment breaks those chemical bonds and makes niacin bioavailable. It also increases the availability of the amino acid tryptophan, which the body uses both as a protein building block and as a precursor to make its own niacin.
Calcium absorption gets a dramatic boost too. Raw corn contains roughly 9 milligrams of calcium per 100 grams. After nixtamalization, that number jumps to around 170 milligrams per 100 grams, because the kernels absorb calcium directly from the lime solution. This contributed to lower rates of bone disease in Mesoamerican populations that depended heavily on corn.
Handling Calcium Hydroxide Safely
Food-grade calcium hydroxide is a strong alkite that can irritate skin, eyes, and lungs. The dry powder is the main concern. When scooping it, avoid creating a dust cloud. Wear gloves and keep it away from your eyes. If you get lime dust on your skin, rinse it off with water rather than rubbing it. The concentrations used for nixtamalization (1 to 2 percent) are mild once dissolved, but the dry powder and any undissolved residue at the bottom of the pot deserve respect. Store it in a sealed container away from moisture.
Troubleshooting Common Problems
If the pericarp won’t come off during washing, you either used too little lime or didn’t cook and steep long enough. Try increasing lime to 2 percent next time, or extend the steep to a full 14 hours. If the masa tastes strongly of lime or has a chemical, soapy flavor, you used too much calcium hydroxide or didn’t wash thoroughly enough. The fix is obvious: less lime, more rinsing.
Corn that falls apart into mush during cooking was either over-limed or simmered too aggressively. Keep the heat at a gentle simmer, not a rolling boil. Old, very dry corn may need slightly longer cooking and steeping times, while fresher dried corn softens faster. Every batch is a little different, and adjusting by feel after a few tries is part of the process. The finished nixtamal should be swollen, tender but intact, with the dark tip (the germ cap) still attached but easy to flick off with a fingernail.