Why You Should Stop Pouring Out Your Potato Cooking Water
Reserving pasta cooking water has long been a recommendation by both home cooks and professional chefs alike, but pasta water isn't the only type you should be collecting. It's recommended to set aside at least some pasta water due to the saturated amount of starches released into the water during the boiling process, which can be used to thicken up sauces and add some salt to soups, stews, other boiled foods, in baking, and even in gardening.
Pasta is far from the only starch-rich food that's commonly boiled. Potatoes contain a large amount of natural starches as well — as much as 18%, per Healthline. Flour (pasta) naturally has more, but potato starches are also chock-full of beneficial minerals and vitamins, including vitamin C and B6, potassium, manganese, and folate. While there are almost endless ways to cook potatoes, one of the more common and easy ways to do so is by boiling. Next time you boil a pot of potatoes, whether for mashed potatoes, soups, or before baking, don't toss out the water.
Potato water as a thickening agent
Similar to pasta water, potato water is full of incredibly valuable starch that can be reused in the kitchen in a variety of ways. If you're boiling potatoes to make mashed potatoes, you especially shouldn't discard the water, as recommended by BBC Food. Instead, once your potatoes are mashed, substitute a bit of the milk with the starchy water, which can help thicken it up. Even better, salt your water during the boiling process, infusing even more flavor into the mashed potatoes
Potato water is a multipurpose thickening agent and can even work to thicken up gravy in place of a cornstarch slurry. Starch is also often used in the preparation of fried foods, as it stores the excess moisture from the meat or vegetable and then gets incredibly crispy in the hot oil, per Kitchen Stories. While this is usually done with dry starch, you could also add potato water into wet batters for frying. Starch can also help firm up pie filling, so as long as your potato water isn't too salty or cloudy, you could add a bit to your next pie filling mixture. As with pasta water, it can also help thicken up a sauce.