Recently, I was at a dinner party which included a gluten-free guest; so naturally, I made a potato-based lemon drizzle cake.
The results, which were surprisingly fluffy and delicious (the BBC recipe it’s based on has five-star reviews, or I’d never have risked it), surprised me.
But on my way home, I had a last-minute panic ― hang on, I thought, the dense, heavy cake used a LOT of baking powder.
Is that gluten-free? And how is it even made?
Some news from Dr Oetker prevented me from sending a post-party alert; it’s “naturally gluten-free,” they say, though some versions can have gluten-containing ingredients in them.
Baking powder is made by combining cream of tartare with bicarbonate of soda.
To stop that combination from getting damp and foaming into oblivion before you can use it, though, most companies add starch to the mix.
If that’s corn starch, potato starch, or in my brand’s case, rice flour, you’re in the clear.
Sometimes brands use gluten-containing starches like wheat starch, but that should be visible on the ingredients list.
This is good news, because (as with my mashed potato cake ― again, don’t knock it until you’ve tried it) a lot of gluten-free recipes need more raising agents than their gluten-containing counterparts.
When you develop gluten in batters or doughs, it sort of acts like the skin of a balloon, trapping any air that rises in the oven.
But gluten-free recipes have no such luxury, meaning you’ll need more rising power.
Baking soda, which contains sodium bicarbonate, needs an acid and a liquid (something like buttermilk does both jobs, which is why it’s so great in soda bread) to rise.
But baking powder, which has an acid built-in in the form of cream of tartare, only needs liquid to rise.
You can substitute one for the other, but you need to make sure you add an acid if you’re putting baking soda in a recipe that asked for baking powder.
Both are gluten-free if they’re not accompanied by a gluten-containing starch.
