Reader Glenda writes to say that she recently made a mistake with her cornbread: she put in too much chemical leavening (exactly how much she doesn’t say). Yet the bread with the extra baking soda turned out virtually identical to the cornbread she makes with the normal, lesser amount. Why is that? she asks. It all has to do with gluten, Glenda. Or rather, the lack thereof.
Cornbread recipes typically call for lot of leavening. The reason: because corn flour has no gluten in it. In wheat flour doughs and batters, gluten creates an elastic batter that traps and holds little bubbles of CO2 and steam. As those bubbles continue to heat, they inflate, and the bread rises. A batter made from corn meal doesn’t have that elasticity, so its ability to trap and hold gas and steam is greatly diminished. Indeed, most of the gas and steam created during baking simply escapes out the top and sides. Yet it rises…why?
I think of rising cornbread like one of those obnoxious fan-driven inflatables you see in front of car dealerships on the interstate. Lots of air goes in and lots of air escapes. However as long as the fan attached to it keeps blowing, the thing stands up. Cornbread is a lot like this. Most of the CO2 created by the baking soda and/or baking powder simply bubbles right out of it. However as long as the batter keeps producing more than it loses, it rises. By the time the reaction is over the eggs in the batter have firmed and the bread remains standing.
This is why you need extra leavening to make most cornbread. It’s also why a little more leavening in the mix won’t make a whole lot of difference in the finished product, as the extra CO2 will simply escape like warm air out an open window. Of course that would only work within limits. Double the leavening in a cornbread recipe and the batter would bubble over the edges of the forms and create a mess. Though shapeless masses that resulted would probably still be delicious. Thanks for a fun question, Glenda!