It’s one of those things so many people who bake wonder about, and I’ve always done too, yet never gotten around to trying to figure it out. Until this afternoon, when I decided I REALLY needed to get a hang of this (and since I’ve taken the day off work, and so wanted to do more than just catch up with work e-mails after a visit to the doc).
So I googled “What is baking powder made of”, and found some really informative stuff which answers some of the most common questions about baking powder and baking soda – can they be used interchangeably?, is it okay to mix the batter and leave it for a while before baking?, why does stuff baked with baking soda sometimes end up with a slightly metallic taste? and so on.
And if you’re really looking for inspiration, there are even recipes for making one’s own baking powder, to avoid the aluminum present in many commercial brands. Now there’s an idea!
I began with this one- by far the most detailed article I found on the subject – here, on huffingtonpost.com, which explains that baking soda is sodium bicarbonate, a chemical with a basic (high) pH. When baking soda is mixed with an acid (low pH), the two instantly react to produce carbon dioxide (CO2) gas. So if baking soda alone is added to a recipe, there must also be a complimentary acidic ingredient such as buttermilk, citrus juice, or cream of tartar in order to produce CO2. Ideally, the amount of acid present in the recipe is balanced to perfectly neutralize the amount of base (baking soda) added. It is in case of a lack of this balance , says this second article, here, that the food ends up with a metallic taste. However, this balance is hard to guarantee, the first article explains, since food acids from natural products can vary based on growing, storage, and manufacturing conditions. So, subtly different results might be seen at different times of year, by using an older lemon for example.
The first article also explains in wonderful detail how baking soda enhances browning, because of the Maillard reaction, and that swapping baking soda for baking powder “…WILL impact your results, even if it’s subtle.” I for one, am kinda convinced after this that the only thing to do, if you like to bake, is to keep enough stock of both so as not to run out of either and thus not to have to consider this substitution.
Of baking powder, the first article says “..is is like baking soda’s more sophisticated big sister. Whereas baking soda is made up only of sodium bicarbonate, baking powder contains both sodium bicarbonate and the acids needed to react with it.” The article also explains why many commercial brands of baking soda contain two acids – one, a fast-acting acid that releases a small burst of CO2 to give the batter body before cooking begins, and a second acid that becomes more soluble at higher temperatures, so it begins to dissolve and produce CO2 during the actual cooking. It is this second acid-base reaction that accounts for the lion’s share of CO2 produced by baking powder and results in a fluffy cake, since the late-stage CO2 produced has less time to escape before the batter sets.
And finally, a recipe for baking powder, if you want to skip the aluminum that’s present in the commercial versions (in the form of sodium aluminum sulfate) -there’s one on the good old beeb’s Good Food site, here, where I’ve found many a great recipe over the years (including a super recipe for the very southern Indian sundal). And if you love a chemistry equation, get your recipe here !
Now that’s what I call a productive afternoon 🙂 Mystery, solved.