Mashed potatoes are universally beloved, and for a good reason — they're cheap, tasty, and relatively easy to make. What's more, they're adaptable to just about every dietary regimen, whether you're vegan, gluten-free, or lactose-intolerant. And they're a staple for holidays such as Thanksgiving.
There are all kinds of recipes and theories about how to make a perfectly fluffy mash. However, many of them involve elaborate amounts of butter, cream, or other assorted dairy products. Turns out, there are astonishingly easy and cheap ways to get your mashed taters to a perfectly fluffy and cloud-like state without adding unnecessary calories to the recipe.
Baking powder and baking soda are both chemical leaveners that make batters rise, which is why they're in almost all recipes for baked goods.
Baking soda needs to be combined with an acidic ingredient of some kind (buttermilk, lemon juice, vinegar, honey, yogurt) to create carbon dioxide, a gas that emits small bubbles and makes the goods fluffy.
Baking powder, which is composed of baking soda and cream of tartar, already contains that acidic ingredient, which is why it's better to use when looking to increase fluffiness in your mashed potatoes.
Some hardcore bakers insist on making their own baking powder rather than buying it from the store, but you can be lazy like me and just buy it.
Theoretically, you could use baking soda in your mashed potatoes to get the same effect, but you will need something acidic in the bowl to create carbon dioxide. Add a dollop of buttermilk or yogurt if they're available.
Before you add the baking powder, there's one other step you can take to ensure that your taters are the fluffiest ever. After you drain them, add them back to the pot and let them sit in the residual heat from cooking for a minute or so. There's no need to turn the flame back on. It will evaporate any excess water in the potatoes so they're not soggy.
If you used the baking soda plus acid approach, you probably have some baking soda leftover. What can you do with it? Well, it can make caramelizing onions faster, and it can help relieve jellyfish stings, make invisible ink, and extinguish small grease fires. Check out Yumi's illustration on unexpected uses for baking soda for more tips. Also, use it to make "hot ice" with vinegar, a fun science project.