Preparing Grain Corn for Cooking

Small-scale corn growing doesn’t have to be all about sweet corn. Use homegrown grain corns and make the best, most nutritious flour and corn meal, the old-fashioned way.

Bloody Butcher corn

At its center of origin in Mexico, corn is prepared by steeping it in an alkaline solution, then rinsing it and cooking the kernels until they are soft.

Photo by David Cavagnaro

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The transformation of hard corn kernels into edible food follows three distinct pathways. Archeologists believe the most ancient method of preparing corn for eating was by popping. The hard, indigestible grain was made palatable and digestible by exploding the kernels over heat. In the Peruvian Andes, the Inca made partially covered clay vessels for the purpose of popping corn. At its center of origin in Mexico, corn is prepared by steeping it in an alkaline solution, then rinsing it and cooking the kernels until they are soft. The softened grain is consumed whole or ground. Popping and alkaline steeping are centuries-old, distinctly American traditions. In contrast, dry milling of corn with stone or steel has roots in the Indo-European tradition of preparing small grains for bread and gruel by using a millstone.

Preparing popcorn

Popcorn kernels explode best when they have exactly 13.5 percent moisture content by weight. When the kernel moisture strays from the optimum, popping expansion is impaired. Storing corn at 75 percent relative humidity achieves the perfect moisture content. If this precise instruction seems overly technical and leaves you with a sinking feeling that you will never have perfect popcorn, join the crowd.

Among the yellowing bulletins I received from Calendula Books was a reprint of a 1946 article, “Conditioning Popcorn to the Proper Moisture Content for Best Popping,” written by S. T. Dexter. At first I presumed this would have the same information given in every other publication on popcorn with some industrial-scale recommendations.

Dexter’s technique is simple. Prepare a saturated salt solution by adding salt to water until no more salt will dissolve. Place your popcorn in a dry mason jar with a paper towel or cloth wet with the salt solution; the paper or cloth should be soaked but not dripping. Seal the jar, and in a few days the kernels will be reconditioned. If you have a sack of old, stale popcorn, it is worth trying to recondition it with this technique before consigning it to the chicken coop.

When popping the corn, use oil with a high smoking point, such as coconut oil. Use enough oil to cover the base of the pan. Add two or three kernels and put the pan on the stove. When the kernels pop, the oil is hot enough to add about a quarter cup of kernels. Cover the pan and shake it to keep the kernels moving. A spatter screen instead of a lid will allow the moisture in the corn to escape from the pan, producing more tender popcorn. The moisture from popping toughens the flakes, so transfer the popcorn to a bowl or colander as soon as it has popped.

Alkaline steeping of corn

Tortillas and tamales are made from whole kernels of dry grain corn that have been steeped in a hot alkaline solution, left to soak in the solution as it cools, and then washed the next day. The process is called nixtamalization, and the treated kernels are called nixtamal. The nixtamal is ground wet to make masa, the wet flour used to make tamales and tortillas. The masa makes a weak, pastelike dough that, with skilled hands, can be molded into tortillas. These are cooked rapidly on a very hot clay surface called a comal. Whole nixtamal is also cooked until the kernels are tender, at which point it is once again called maíz, or corn. Masa and the whole treated kernels are also available in a dry form.

Preparing nixtamal. Nixtamal is easy to prepare in the home kitchen. Any type of corn can be made into nixtamal. We use both Roy’s Calais Flint and Amish Butter with excellent results. We have also made it from dent and flour corn. Flint corn and popcorn have a bit more “chew” to the kernels, and I think the flavor from the higher oil and protein content of those types of corn stands up better to the lime (calcium hydroxide or cal, Spanish for “lime”). Mexican markets have it in stock, often in a small 2-ounce package, which is all you need for a recipe. Slacked lime is also sold for pickling during the summer pickling season. It is caustic and should be handled with caution, especially around children.

In an enamel or stainless steel pan, combine about 1-1/2 pounds corn kernels with 2 heaping tablespoons of slacked lime and cover with water by about 2 inches. Simmer gently for 30 minutes, to soften the pericarp. Do not boil; you don’t want to cook the kernel. Boiling will result in a bitter off-flavor. You will notice that the lime imparts a familiar flavor and fragrance to the corn; many popular snack foods, such as corn chips and corn nuts, use nixtamal as the primary ingredient. Remove from the heat and let the mixture steep overnight at room temperature.

The next day, pour off the lime solution into the compost bucket and rinse the kernels vigorously in clean water to get rid of residual lime. Rub the kernels between your fingers as you wash them and the pericarp will slough away, leaving the yellow or white endosperm. Sometimes the pericarp is hard to remove entirely, especially in dark-pigmented flint varieties. If you want “clean” nixtamal that will shed its pericarp, use a white or yellow kernel and stay away from the red and purple types. The pericarp remnants do not affect the flavor or cooking quality of the nixtamal — removing it is purely a visual consideration.

Some cooks recommend dislodging the embryos from the kernels. As far as I can determine, this is an aesthetic call, and certainly not necessary with regard to flavor. In fact, you will discard a good deal of nutritional content in doing so.

It is possible that some types of corn have a bitter embryo, and if that is the case, ridding the corn of the embryo makes sense. Taste the corn with and without the embryo and decide for yourself rather than leaving it to the dictates of custom.

Put the kernels in the pan and add enough water to cover them by about 1 inch. Put the pan on the burner and simmer for about 30 to 45 minutes until soft. Salt the cooking broth to taste. Allow the corn kernels to cool. This recipe will produce about 3 pounds of nixtamalized kernels ready to eat.

You can dry the kernels on a screen or in a dehydrator before the final cooking step. When you are ready to use them, cover with water and soak overnight. The next day, cook until soft as described above.

Preparing hominy. The North American variant of nixtamal, hominy, is produced commercially using lye instead of slacked lime in the alkaline steeping process. Originally, lye extracted from wood ash was used, contributing calcium, potassium and trace minerals to the corn.

In the southern United States, hominy is made using food-grade lye as the alkalizing agent. Lye (sodium hydroxide) in its pure state is extremely caustic, much more so than slacked lime; it will eat away your skin as a reward for carelessness. The lye comes as dry crystalline beads. In the lutefisk and pretzel belt of the midwestern United States, food-grade lye is available at the grocer. In other places, it can be ordered for delivery to your house. When opening the container and measuring it, wear gloves and goggles as a safety precaution. I open the container and measure the lye outdoors so if some does fall to the ground, I can hose down the area easily. The unused lye must be stored in a dry, safe place well out of reach of children. There is no need to be fearful, just cautious. Midwestern families regularly prepare lutefisk and pretzels using lye without incident.

To make this form of hominy, we use a large, stainless steel stock pan, 16-quart or larger, the deeper and bigger the better so as to lessen the chance of the lye water splashing on us. A large enameled pan in good condition is acceptable. Never use aluminum or copper pans. Although the lye dissolved in water is less caustic than the crystals, you still don’t want the hot lye water splashing on your skin.

Put 2 cups whole corn kernels and 2 quarts water in the pan. Carefully add 1 tablespoon food-grade lye beads to the pan. Stir and bring to a boil. Turn down the heat to medium and cook at a low boil for 30 minutes. Turn off the heat and let the kernels steep for 20 minutes. Dilute the cooking liquid with plenty of water, then carefully drain off the water solution into the sink. Wash the kernels several times in clean water until the washing water runs clear.

Leave the kernels in clean water for 30 minutes. Drain them and add water to cover by 1 inch. Bring to a boil, then turn down the heat and cook the kernels at a simmer until they are tender, usually 1 to 2 hours, depending on the corn variety.

Hominy made with lye has a sharp soda flavor reminiscent of soda bread. Traditionally it is served as a side dish dressed with some butter and maybe a bit of cream, which softens the flavor. If you are on a sodium-restricted diet, corn prepared with calcium hydroxide, slacked lime, is the better choice.

The prepared hominy will store in the refrigerator for 5 to 7 days.

For longer periods of storage, thoroughly dry the lye-treated kernels after the final soaking and store in the pantry. When you’re ready to use them, soak the kernels overnight and cook until tender. You can also grind the dry kernels as described below for classic hominy grits.

Hominy is cooked and used whole, or dried and coarsely ground to make hominy grits. It has remained a traditional food of the South. The porridge made from ground hominy is called grits, hominy, or hominy grits, depending on the county where it is served. Where hominy refers to the porridge, “big hominy” is often used to identify the whole kernel form. For the most part, Southern hominy, either big or grits, is made from a white corn variety with a large kernel, such as Hickory King or Boone County White.

Preparing dry corn by milling

Instead of adopting the American methods of preparing corn by popping or alkaline steeping, on the other continents of the world corn is ground dry and then used for bread or porridge.

That first June, when we planted those four rows of Roy’s Calais Flint, we did it on impulse. By the end of August, it looked as though the old flint just might pull through for us. An exceptional autumn followed, with a long Indian summer, and the ears dried perfectly in the field. We had a room full of corn, and now we needed a way to mill it. The choices were steel or stone.

The steel burr mill. Although I favor the granite gristmill for grinding corn, it represents a sizable investment. Steel burr mills are available (as are small hand-cranked stone mills) and will grind corn and other grains satisfactorily. Many of these mills are relatively cheap, but the best quality machines approach a stone mill in price.

Separating the samp, grits and meal. The first few pounds of corn we ground went well, but the meal that came out of the mill had a coarse fraction that needed to be separated from the finer meal. On a small scale, a household sieve worked, but we needed a better solution. We gave the people at Meadows Mills a call, and a couple days later, a tube of bolting cloth arrived.

When corn is ground, a wide range of corn particles exits the stones. The biggest are flakes from the pericarp and the pedicels, along with some debris called samp. These larger particles are usually sifted out for more even cooking times. Next are the grits, followed by meal and flour.

The process of separating or sifting the ground grain into different particle sizes is called “bolting.” The term “bolt” has its roots in the rolls of fabric purchased for sifting. For a couple of millennia, the bolts were cloth woven from natural fibers stretched on a frame. The finest were made of silk, with linen and hemp used for coarser bolts. Modern bolts are still woven cloth, but stainless steel wire has replaced the natural fibers. They are standardized and numerically defined by the number of wires per inch. For example, a No. 14 mesh has 14 threads per inch. We made a frame out of lightweight, non-splintering wood for each bolt mesh.

Grits pass through the No. 12 mesh but are trapped by the No. 18 mesh. Cornmeal is what passes through the No. 18 mesh, and corn flour passes through the No. 26 mesh. Initially, we separated out the grits and meal. It was more work than necessary, and we now run the ground corn through a No. 14 mesh and call it a day. We lose a bit of the very coarse grits, which we feed to the birds. The resulting mix of grits and fine meal seems to work in most recipes calling for one or the other. The result is what the Italians call farina per polenta di mais, or “meal for polenta of corn”; sometimes it is called farina per polenta di gran turco, using the old “Turkish wheat” epithet for corn. Polenta simply means cooked porridge, and it can be made from ground corn, chestnuts, buckwheat, fava beans, peas, emmer or millet. In the United States, it is customary to separate the grits and meal, but we have found the extra work unnecessary.

Traditions vary by region, and some growers may separate the meal from the grits. In that case, start with a No. 12 bolt to pull off the coarsest bits, then separate the fine meal from the grits with a No. 18 bolt.

We grind our corn to order and sell it fresh. Whole-grain ground corn, or full-fat milled corn as food technologists define it, is highly perishable. The fats in the germ start to go rancid once they are exposed to the air after grinding. Full-fat corn is also an irresistible elixir to grain and flour pests. Where we store our grain, we use pantry pest traps that lure the moths to a sticky sheet, and we also keep the room as clean as possible.

We recommend storing the ground corn in the freezer and using it as quickly as possible. We use two-quart mason jars so it doesn’t pick up other flavors.

The best part of growing corn in the backyard is cooking up and savoring the corn that was prepared just moments or hours earlier from the mill.


Anthony Boutard is a widely recognized advocate in the local food movement, well-known for his efforts in reviving long-lost crops and bringing little-known varieties to the market. He and his wife, Carol, own Ayers Creek Farm, a 144-acre organic market farm in Gaston, Oregon. Purchase a copy of Beautiful Corn at the GRIT store.