Why doesn’t corn meal thicken?
Reader Kati wonders why cornstarch (corn flour) is so effective as a thickener when corn meal makes such a poor thickener. She alludes to some recent kitchen disaster that resulted from an attempt substitute one for the other. Reader Kari, I feel your pain. The answer lies in the way the two flours are processed.
Corn kernels are the seeds of the maize plant. As such, each has a tough outer covering known as a pericarp, which is similar to a bran layer on a wheat berry. Each also has a fatty germ which when pressed yields corn oil. The majority of the kernel is the starchy endosperm.
It’s the starch in the endosperm that gels and thickens liquids, but in order to work it has to be liberated from the confines of the pericarp. Sure, if you simply grind the whole kernel up into meal and immerse it in hot liquid you will get some gelling, but because much of the starch is still attached to jagged pieces of endosperm and germ, the effect will be limited.
Contrast this simple grinding with the way cornstarch is actually produced. The kernels are soaked in water for two or three days, during which time the endosperm gets very soft and the pericarps get very, very flexible. The kernels are then passed through rollers which squeeze out the endosperm (which is mostly just dissolved starch by then) and pinch off the germ. The whole mess is then rinsed and spun in a centrifuge. The starchy water spins out and is dried to make cornstarch.
What you have when you’re done is a powder that’s almost pure starch: small granules that are almost entirely free of all the flotsam and jetsam found in corn meal. Immersed in warm liquid they disperse nicely and gelatinize (thicken) beautifully, much better than meal. But then you recently found that out, reader Kati. My condolences. Better luck next time!
While it is true that cornmeal does not thicken in the same way that corn starch does, I have made a James Beard chicken recipe for years that has lots of wonderful “juices”. Near the end of the cooking, I throw about 1/2 cup cornmeal into the casserole, stir everything well, and put it back in the oven for about 30 minutes. The result is fabulous chicken with a soft tamale-like accompaniment. It is even more tamale-like the next day, after sitting in the fridge overnight. By using cornmeal, you will never get a nice gravy, but you can end up with polenta or soft tamale. It could be good!
Masa harena, another corn product, thickens somewhere in between corn starch and corn meal. I make a roux of masa and butter, flavor it with chili powder and salt, then add water to make a chili gravy for my enchiladas. I think it’s processed somewhat like hominy, but I’d love to learn why it thickens better than corn meal (which doesn’t substitute well in my chili gravy, either, also learned by experience.)
so, this is a total aside, but your detailed description reminded me why almost all corstarch gives me a terrible stomach ache but corn is just fine:
“The kernels are soaked in water for two or three days, during which time the endosperm gets very soft and the pericarps get very, very flexible.”
My understanding is that this water is typically sulfited to help soften the corn. It is also done to oats prior to ‘rolling’, and why oatmeal makes me ill but steel cut oats are fine.
Hope you don’t mind this tangent! I’m on the search for cornstarch I can eat because it’s such a lovely thickener.
Hey Jennifer!
From what I know SO2 (sulphur dioxide) is applied later in the process to help preserve it, but yes I think you’re more or less correct in what you say. Sorry to hear about your sensitivity, but you’re definitely not alone in that. Good luck finding an alternative!
Cheers and thanks for the comment,
– Joe
I know it isn’t quite as good as cornstarch and there are ways you have to use it vs. cornstarch to get a similar effect but arrowroot starch has always been considered a good alternative, Jennifer.
Thanks, Linda!
– Joe