What’s the difference between corn meal and corn masa?

It’s a good question, because on an intuitive level one would think that if a corn tortilla is a simple pancake made of ground corn, there really shouldn’t be that much difference between finely ground corn meal and masa harina (literally “dough flour”). In reality there’s a huge difference, which can be summed up in a single word: nixtamalization. Yeah, that’s a mouthful. It comes from the Aztec word “nixtamal” which, loosely translated, means “ash dough.”

Not very appetizing by the sound of it. However what ancient Mesoamericans discovered 3,500 years ago is that when you boil and then soak raw corn kernels together with ashes, some very interesting things happen. Notably, the outer hulls (pericarps) of the kernels loosen to the point that they can be slipped off. Further, what’s left — the endosperm and germ of the kernels — becomes quite soft and pliable, easily ground into a dough that’s perfect for making tortillas.

So nixtamalization is all about heat and water then? Er, not quite. The key component is really the ash, which, long-time readers of joepastry.com may remember, has a high pH. Add a handful to a pot of water and you get an alkaline solution that goes to work dissolving the glues that hold the walls of the pericarp cells together (the hemicellulose and pectins). The pericarp loosens and falls off, and the endosperm swells as it takes in more and more of the chemical-laden water. As it does, the tight bundles of starch molecules in the endosperm start to come apart. What you get, once the corn is finally drained and washed, is a processed corn product that’s easily ground into a dough that’s just smooth enough and just elastic enough to be formed into a thin cake like a tortilla.

Neat. But it raises the question: how did the ancient Mesoamericans hit on this process? Unknown. It may have started when someone mixed a few wood ashes in with some corn gruel (a common technique that indigenous American peoples used to lighten — really leaven — cakes made from grains). But who knows? Wood ashes (which contain potassium carbonate) weren’t the only alkaline compounds available to the peoples of that time. Naturally occurring lime (calcium carbonate-rich limestone and/or chalk deposits) were also used, as were the ashes of burned mussel shells.

These days, most people who want to make their own corn masa use a commercially-made product that simply goes by the name of “cal” in Mexico. Calcium hydroxide is what it is, commonly known as “slaked” (dissolvable) lime in America. It can be found in most Mexican markets in the spice section.

Buying the cal and boiling and steeping the corn is the easy part, however. The real challenge when it comes to making one’s own corn masa is the grinding. Getting it fine enough to make tortillas is no easy task. Food processors aren’t good enough. What’s needed is either a plate grinder or a good, old-fashioned metate. I’ve never used one, but I can imagine they call for more elbow grease than I’d be willing to put in for home-made tortillas. But those of you who might be interested, knock yourselves out! You can get them in Mexican markets as well. They cost less than you’d think.

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6 Responses to What’s the difference between corn meal and corn masa?

  1. Thank you for taking the time to publish this information.
    However, I have three remaining questions.

    1. when it says soak corn meal. is this fresh corn that has been milled? or from a bag i bought?
    2. after I soak the corn and rinse, don’t I have to dry it
    before grinding it? no article talks about after the soaking.
    Now I have cooked soaked corn and if you could elaberate on what is next that would be awsome.
    3.If I use wood ash I don’t need to use the lime water?
    also what makes blue corn? (blue tortillia)
    Thanks again you have been a big help.
    Learning to do more from my kitchen and less from store products.
    Jacqueline

    • joepastry says:

      Hey Jacqueline!

      If you’re making your own masa you’ll want to soak whole dried corn kernels. They can be a little tough to find, but it is possible. I’d also use cal and not wood ashes, since a.) you don’t know the alkalinity of your ash and it may not work, and b.) your masa won’t taste like a fireplace. Once the kernels have soaked you’ll want to pinch off the pericarps (skins) and then grind/mash the starch while it’s still wet.

      Regarding blue corn, that’s actually a variety of corn that grows blue on the ear. It’s pretty neat looking stuff, but odds are you’ll never find dried blue corn kernels for masa…but you can always try!

      Let me know how the project goes!

      - Joe

  2. Simone says:

    Is there a nutrutional difference between corn meal and masa?

    • joepastry says:

      Great question! I’ll answer that on the blog if that’s OK. Have a look at the main window a little later today.

      - Joe

      • Jesse says:

        No need to look it up. The nixtamalization process frees up niacin so that your body can absorb it. If you tried to live on a corn-beans-squash and some meat when you can get it (much like many of the ancient natives) diet without nixtamalization, you’d get a disease called pellagra as a result of the niacin deficiency. It probably destroys a few nutritional items too, but if corn is your staple with no other sources of niacin, the trade off is more than worth it.

        FWIW, I planted painted mountain corn and some Navajo Blue corn this year, and I’m interested on seeing what the hominy from those two varieties taste like. I can get blue corn hominy in the stores, but it’s pricey.

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