Which is the better cornmeal substitute?
I have a carrot bread (breakfast bread, like a healthier carrot cake) recipe that calls for 2 cups a-p flour, 1/2 cup whole wheat, and 1/2 cup cornmeal.
I have everything else, but I don't have cornmeal, per se.
Can I substitute polenta or MaSeca, and which would you use if you were me?
Polenta is probably choice #1. Maseca has some other ingredients (I think) and might affect (though not drastically) your end result. Polenta is cornmeal is grits... At least for your purposes. Unfortunately, plain cornmeal is sometimes hard to come by at the regular grocery store. They all seem to be pre-mixed with other ingredients.
Substituting Maseca (or other brand of masa harina) for corn meal in any recipe will probably be a disaster. The type of corn is not the same, but the real difference is masa is made by boiling the corn in a lye solution before grinding. Totally changes the taste and consistency. As others have suggested, polenta should work just fine.
And don't even think about making tamales using corn meal.
I make a pumpkin (or sweet potato) bread with the same total 3 cups of 'flour' (2 loaves). I usually use 1 1/2 c of white whole wheat, and split the other 1 1/2c among oat bran, wheat bran, corn meal (or corn flour), and ground nuts (almond meal). As long as the total quantity is the same, the exact mix does not seem to matter.
As was discussed on a recent polenta/grits thread, polenta may or may not be the same as corn meal. Grind may be similar, or coarser. One may be dent corn, the other flint, or they may be the same. For this quantity if probably doesn't matter. You could also substitute whole wheat for the cornmeal.