Why is there vinegar in the cupcake batter? Baking soda, the ingredient that makes these cupcakes rise, starts to work only when it comes in contact with an acidic ingredient. Some common types used in baking are lemon juice, buttermilk and vinegar. Sweet balsamic vinegar, which has a flavor that goes well with the rich flavor of cocoa, is added to the batter here. It gives these cupcakes a deep, full flavor. Surprisingly, they wont taste anything like vinegar after the batter is baked.