How to get intended taste using baking powder instead of acid + baking soda? A coffee cake recipe calls for using sour cream and baking soda. I understand that acid + baking soda is a leavening agent and you can use them as a substitute for baking powder. But I only have baking powder.


If I use baking powder instead, will the taste of the coffee cake be majorly affected? It won't have the sourness of the cream anymore, but how important is that in a coffee cake?
Can I add something else along with the baking powder so I can get something close to the intended original taste?
If you use baking powder instead of baking soda in this recipe, you'll have an excess of acid.  That's not too bad (an excess of baking soda gives a soapy, bitter flavour).  The effect is likely to be as if your sour cream was slightly more sour. If you wish to tone that effect down you could  replace a small amount of your sour cream with cream or even milk.

The rise may be slightly affected but this should be minor; with or without the acid in the baking powder you're limited by the alkaline component. Baking powder is usally double-acting meaning some of the reaction is delayed until it gets hot. Sour cream plus baking soda is likely to start reacting immediately, so substituting the other way would be worse.