I have a package of Koopmans Oud-Hollandse Appelkaneel Cake mix that I think my family bought from Aldi a few years back, which is well past its expiration date. I know that baking powder in cake mixes can expire over time as the acidic and basic chemicals slowly react with each other. On the ingredients list on its (Australian) English-language sticker, it states that it contains Raising Agents 450 and 500, and looking online that makes it sound like it has baking soda rather than backing powder, right? The recipe calls for the addition of a chopped apple, which I suppose might contribute the acidity for baking soda to rise; I'm planning on adding frozen mango chunks instead, since those are what I have readily on hand.
If it is baking powder, should I add some baking soda of my own, and if so, how much? A teaspoon?
However, it also calls for the 175g of butter or margarine that is added to be "whisked with a mixer until smooth and creamy", and for the resulting batter to be continued to be mixed after adding the cake mix and eggs are added to the butter. Presumably, this is also another way for air to be added to the batter. However, I don't have a mixer, just an immersion blender. Would this work? Should I add a bit of full-cream milk to the butter to make the whipping easier, since you just need 30% fat content to make it whippable?
Given the resources I have available, and the substitutions I'm planning on making, is making this cake a viable endeavor, or will I just wind up with something that's failed to rise into a proper cake?
