Thanks! I was actually looking at info on Dutch process vs natural again today and came to the same conclusion. I was just going to tell OP and saw you told me the same yesterday :)
@GardenGeek@europe.pub, the recipe is probably designed for Dutch process coca powder. Natural is acidic (low Ph), so it generally gets paired with baking soda (high Ph) to produce leavening. Dutch process ph neutral, so it gets paired with baking powder which leaven’s on its own.
my imperfect understanding is as follows:
Leavening is produced by the chemical reaction of an acid mixing with a base. This reaction is strongest when the acid and base are balanced (or close to it); the more out of balance they are, the weaker the reaction.
Baking powder is a balanced acid and base, so it provides the best leavening when the rest of the recipe is ph neutral. If the rest of the recipe is acidic (or basic) it will weaken the reaction. It will still work, though; it just won’t rise as much as it would have if the recipe were in balance.
So… baking powder is a “safe bet”. It will still leaven if you use it with natural coca powder (acidic), but you would probably get more rise if you (A) used Dutch process instead, or (B) add the right amount of baking soda to neutralize the extra acidity.
GIANT CAVEAT: I like food science. I cook a lot… but I don’t bake a lot. So I’m mostly just reciting stuff I’ve learned. I probably don’t have this all precisely right. And I’m not sure significant the effect of extra acidity is; For all I know the effect on leavening is small enough that it doesn’t really matter.