By Joanne Thomas

Sour powdered sugar, an ingredient used most often in candy making, is an unusual item that's not easy to find. Fortunately, its two components – powdered sugar and citric acid, also known as sour salt – are readily available in stores and online. Blend the two and you have at your fingertips a magical source of the tangy, sweet-sour, mouth-puckering flavor that makes sour candies so tempting. If you've delved into the wonderful world of homemade candies so you can avoid mystery ingredients, sour sugar will be a great addition to your pantry.

Powdered sugar in a sifter ready for dusting
credit: fotyma/iStock/GettyImages

What Is Sour Sugar?

Sour sugar is sugar blended with citric acid, which you can find on the bakery aisle in well-stocked supermarkets, as well as in specialty stores and online. Be sure to purchase citric acid, also sold under the name "sour salt," that's labeled as food grade. Citric acid is derived from citrus peels, and it's available in powdered and crystal form. For making sour powdered sugar, you should buy the powdered version. A small package will do, as a little goes a long way.

Making Sour Powdered Sugar

All you need to do to make sour powdered sugar is mix powdered sugar with citric acid. If you have only granulated sugar on hand, you can blitz it into a fine powder in a food processor as a suitable substitute. For every half-cup of sugar, use around 1 to 3 tablespoons of citric acid, depending on how sour you want it to be. Start with less, taste the sour sugar and add a little more if necessary.

The best way to blend the sugar and citric acid without making a mess or finding yourself inside a sweet-sour cloud is to seal the ingredients together inside a zipper food storage bag. Shake and turn the bag repeatedly until you've thoroughly blended the sugar and citric acid. Alternatively, gently stir the ingredients together in a mixing bowl using a spoon or whisk.

What to Do With Sour Sugar

Use sour powdered sugar in the same way you would regular powdered sugar, whenever you want to add a tart taste. Dust it over candies, cookies and cakes, or sprinkle some over slices of fresh fruit when you have a sour candy craving but want something healthier. It's especially good with citrus desserts like lemon bars and key lime pie. Blend sour powdered sugar with water or fruit juice to make icing or a glaze.

With the citric acid you now have in your pantry, you can make tart frozen yogurt. A tiny amount boosts the sourness of sourdough bread. Try adding a pinch to savory dishes, too. Citric acid is also useful for cheese-making, canning and making sausages. Plus, you can use it to deep-clean your dishwasher and de-scale your coffee maker.