Why do you add vinegar to cupcakes?

Most likely, the mix contains baking soda. When you combine baking soda and vinegar... well, you've done that experiment. Many mixes have baking powder instead, which contains its own acid that reacts when you add water. read more

Vinegar makes cake batter more acidic; the acidity, in turn, causes the proteins in the flour to set the cake as it bakes. This results in a cake that is fluffy yet still moist. You don't have to eliminate eggs to achieve the same effect; just use a little vinegar in a traditional cake recipe or with a boxed cake mix. read more

Don't worry, in order for you to taste the vinegar in the cake, you would have to use too much of it, which would either make the cake inedible or not bake correctly. One Tablespoon per one standard layer is usually the right amount. But if you are making cake with other items in it, like fruit or nuts, you might want to add a little bit more. read more