Nixtamalized Corn For Posole

Nixtamalized Cascade Ruby Gold flint corn

This turned out to be a rather confusing and complicated subject so I apologize if this post seems a bit rambling. Generally speaking, nixtamalization is the process of treating dried corn kernels with an alkaline solution to remove the tough pericarp. The process also improves the nutritional value of the grain, making niacin available and improving the protein content. It also changes the starch to allow it to form a malleable dough, masa, which is used to make corn tortillas. (Read the Wikipedia articles if you want the gory details).

That sounds pretty straightforward, but in practice I found it to be not so simple. Try looking up a recipe for treating corn to make posole or hominy (same thing). More often than not what you get is a recipe for the finished dish (a soup or stew) that calls for canned hominy (yuck) or dried posole. Dried posole is a perfectly good, even fabulously good product and is what got me started on my quest to make my own from scratch from homegrown corn. It got to be confusing when I wanted to learn the process of turning raw dried corn kernels into posole.

So that alkaline solution - it can be food grade lye which is sodium hydroxide, or you can go to a Latin American market and buy "Cal" which is calcium hydroxide (slaked lime), or find a bag of pickling lime which is also calcium hydroxide, or you can use clean hardwood ashes to make a weak lye solution. Some people use baking soda but I've read that it produces funky flavors.

Anyway, I have to admit that I did a bit of experimenting with wood ashes, we burn a fair amount of oak in the colder months. I had some degree of success but the mess wasn't worth the effort. It was so much easier to go to Mi Pueblo and buy a package of Cal, surprisingly easier than buying pickling lime which I could not find anywhere. So I'll skip the details of my wood ash experiments.

Even after settling on which alkaline solution to use there was still some experimenting to do. One method I found is to boil the lime in water, let it steep until the lime settles to the bottom of the pot, then drain off the clear alkalized water to treat the corn. That's also what you can do if you use ashes. Another method is to boil up the lime in the water with the corn kernels. Quite frankly I couldn't see the benefit to adding another 5 or 6 hours or so to the process to make a clear solution. I went straight for the put it all in the pot together process.

The next area of confusion is how much lime to use? The advice was all over the place - here's the notes I took as I trolled the web:

- 1/3 cup cal : 10 cups water (Anson Mills) solution (the clear alkalized water method)
- 1/4 cup pickling lime : 10 cups water (howtomakehominy.com) solution
- 2 tablespoons Cal : 6 cups water (decolonizeyourdiet) direct
- 1% cal by weight of corn (i.e. 10 grams cal : 1 kg corn), amount of water irrelevant (cookingissues.com) you can use too little but you can't use too much since the cal dissolves into the water as it is used (supposedly) direct
- 2 tablespoons cal per pound of corn (2 tablespoons cal = 15 grams) (1 kg = 2.2 lb) direct

And to add to my confusion, there seems to be two approaches to making posole/hominy -

1. First soak the corn overnight in the alkaline solution and then cook it until done in the same solution, rub off the skins and rinse until clean.
2. Simmer the corn for a short period of time in the alkaline solution and then let it soak overnight. Then rub off the skins and rinse until clean. Then cook in fresh water until done. 

Diana Kennedy's recipe in The Art of Mexican Cooking was shockingly a total failure when I tried it - it is a version of approach #2, only she skips the soaking step and her recommended cooking time was far too short.

Here's what finally worked for me. I settled on the 2 tablespoons per pound of corn in a gallon of water. A pound of corn makes a HUGE amount of posole so my experiments were limited to 1/4 pound of dried corn for each attempt. By the way, I did not use my precious limited harvest of homegrown corn for my experiments, I purchased dried white corn from the bulk bin at Mi Tierra market and used that until I felt pretty confident that I had found a method that works.

Then I went for approach #2 and what I finally figured out is that the process just can't be rushed. Slow cooking is best, forget trying to speed things up with a pressure cooker, no way, it doesn't work.

Here's the formula with which I've had repeated success.

Nixtamalized Corn for Posole

1/2 pound corn kernels
1 tablespoon "Cal" or pickling lime
2 quarts water

Combine the corn, Cal, and water in a large nonreactive pot. Bring to almost a boil, turn the heat down so the mixture barely simmers and cook for about 35 minutes or until the skins start to slip. Be careful, the solution is caustic - remove a kernel from the solution with a spoon, rinse it off, then test by rubbing between your fingers. Don't worry when the solution turns yellow, that's what happens, even with white corn. Remove the pot from the heat, cover and let sit 8 hours or overnight.

The next morning the solution will look like this. There's a fine film on top of the water and all the lime has settled to the bottom of the pot.

Corn kernels after soaking overnight

Stir it up and it looks like this (which is also what it looks like when it's first cooking). Pour off the liquid and add fresh water. Rinse again and then rub the corn kernels between your palms or just work them with your fingers. Rinse again and repeat rubbing. Repeat rinsing and rubbing until the kernels are skinned and water runs clear. (Next experiment is to try making masa for tortillas, the cleaned soaked kernels are ground at this point to make the dough, but there seems to be variation in methods so more research is required...)

Here's the cleaned corn kernels ready for cooking. If you want your kernels to "bloom" or expand dramatically then you need to pick off all the hard little dark beaks from the ends of each kernel. I skipped that step.

For comparison, on the left is raw dry kernels of Cascade Ruby Gold corn and on the right is the nixtamalized corn of the same variety.

I liken the process of cooking posole to the process of cooking dry beans. You start with a raw dry product, soak it, and then cook it, albeit, the soaking process is a bit different for posole. Unlike soaked beans though, you have the option of drying the corn again. The dried posole can be rehydrated and cooked up like fresh posole.

One key thing I discovered through trial and error is to not boil posole, you're much more likely to get a gummy mess if you try to rush the process by boiling it. It needs to cook at a bare simmer, a slow cooker would be ideal but I don't have one so I cook the corn in an enameled cast iron pot (I have a Staub which is like Le Creuset), covered, in a 250º oven. Do you remember I said this process can't be rushed? Really, it can't. I let this batch cook for 6 hours and then it got to cool in the oven. I waited until it had cooked 4 hours to add salt, at which time I also topped the pot off with some hot water. I start testing the corn after a couple of hours. It's ready some time after the kernels have split. I wait until some of them have burst fully open (the ones that lost their beaks). If you remove the dark tips of the all kernels then all the kernels should burst open. It is quite chewy, but pleasantly so, the kernels should be cooked through with no hard centers. It has the flavor of a good tortilla chip, only chewy instead of crunchy. What can I say, I'm not good at describing flavors.

The cooked posole can be eaten hot out of the pot with just some butter or whatever seasoning you desire. A classic Mexican dish that features posole is Pozole Verde (it's spelled with a "z" in Mexico). It's also found in Menudo, the Mexican tripe stew. I don't worry about using it in authentic traditional dishes though. This batch, along with its broth, went into a simple stew with chunks of Tromba D'Albenga squash, plenty of onion, chopped roasted green Anaheim peppers, jalapeños, a bit of leftover chopped smoked pork shank and other seasonings. It's also an excellent addition to soup.

The cooked posole keeps well in its broth in the fridge for about a week and it also freezes well.

Just about any dry corn except popcorn or sweet corn can be nixtamalized. I've been using Cascade Ruby Gold flint corn that I grew last year. Cascade Ruby Gold is an open pollinated variety developed by Carol Deppe. The colors of the cobs range from red, red-brown, dark red, orange-gold, maple-gold, gold, and yellow with an interior kernel color of yellow or gold. When I hulled my ears I separated them into gold and red. Later this year I hope I'll be able to make posole from the two flour corns that are in the garden now - Mandan Parching Lavender and Taos Pueblo Blue. It will be interesting to see if flour corn cooks up differently than flint corn. I suspect that their starchier kernels may be less chewy than the flint corns.

If you want some really good dried posole without processing your own you can get white posole from Rancho Gordo, and blue or white posole from Native Seeds/SEARCH). I wish I could find a source for bulk heirloom dry corn. There's a number of seed sources for heirloom corn, and a few options for interesting corn meal or grits. But if you don't want to grow it yourself it seems you are out of luck. I guess I'll keep on growing my own.