Baking soda reacts with an acid ingredient (in this recipe it's buttermilk; in muffins it's often juice or fruit puree) to make bubbles and leaven the dough. If you wait too long, or stir too much, between "baking soda touches buttermilk" and "dough cooks," the bubbles will deflate.
Baking powder makes bubbles in the heat of the oven. So if you forgot to preheat your oven and had to let the dough sit around after mixing? The baking-soda bubbles would be gone, but you'd still get some leavening from the baking-powder bubbles. It's a useful backup for that kind of thing going wrong. And if everything goes right, then you have both kinds of bubbles leavening the cake. You end up with a different texture if you blow bubbles in a liquid and make the bubbly liquid stiffen up, than if you blow bubbles in goo that is already partly-solidified.
![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
no subject
Date: 2014-11-11 11:45 pm (UTC)Baking powder makes bubbles in the heat of the oven. So if you forgot to preheat your oven and had to let the dough sit around after mixing? The baking-soda bubbles would be gone, but you'd still get some leavening from the baking-powder bubbles. It's a useful backup for that kind of thing going wrong. And if everything goes right, then you have both kinds of bubbles leavening the cake. You end up with a different texture if you blow bubbles in a liquid and make the bubbly liquid stiffen up, than if you blow bubbles in goo that is already partly-solidified.