One look on the internet for a specific dessert, and you'll find an Asian recipe, a French recipe and even a British recipe. Most likely, all will have different names for the same ingredient, and interpreting them can get confusing. But when it comes to sugar and caster sugar, they're NOT the same thing. While the two sugars can be used interchangeably, the proof of the difference is in the pudding. Caster sugar and granulated sugar are both sugar, but caster sugar is more finely ground. Some call it baker's sugar; others refer to it as superfine sugar. And it does make a difference in your baking results.
What Is Caster Sugar?
It's not confectioners' sugar, and it's not granulated sugar. Caster sugar is sugar that's ground to a superfine consistency. If you've baked for years without using caster sugar, you might want to consider investigating the difference between it and regular sugar. The fine granules break down differently, with caster sugar adding more lift and flavor to specific recipes.
Baking is a science; we've all heard that before. And sugar is one of the scientific anomalies that must feed into our bank of bakery information. Both regular sugar and caster sugar react differently to changes in temperature and the ingredients they're paired with. Butter is one example.
When mixing a batter using regular sugar and butter, it takes a lot longer to break down the grains of sugar so they're not evident in the batter. The same happens when making meringue. You have to over-mix the egg whites when mixing to dissipate the sugar granules. With caster sugar, blending and mixing are less time-consuming and more appealing when biting into a cookie.
Buying Caster Sugar in the United States
You no longer have to go to the United Kingdom to buy caster sugar. American sugar producers finally realized that American cooks like to bake and are particular when it comes to ingredients. Baking insiders know to go to the bakery department of their favorite grocery store and ask for "baking sugar," knowing they're getting caster sugar.
Up-scale supermarkets also offer caster sugar in small packages at large prices. But paying a lot of money for that tiny bag doesn't fit into most budgets. So along came big sugar producer Dixie Crystals. They studied their market and realized that superfine sugar was the backbone of Latin American coffee drinks. Considering that the Hispanic population drinks a lot of sugared coffee, the extra fine grind that dissolves quickly works best. The rest is Dixie Crystal history.
Look for the light brown bag of sugar on the shelf in your grocery store and see "extra fine" written on the front of the bag. Ethnic, Spanish grocery stores often have this sugar on sale, unlike regular grocery stores that mark the price a bit above granulated sugar but less than the little bags of specialty caster sugar.
Caster Sugar Substitutes
If you can't find or afford caster sugar, you can make your own. Dump some regular ground sugar into a food processor or blender; cover it with a towel to subdue the dust that flies out; and turn on the machine. It'll take just 1 to 2 minutes for the sugar to become finely ground, but be careful that you don't grind it so finely that it becomes confectioners' sugar. Or, you can use a mortar and pestle and hand grind the sugar. The granules won't be uniform, but they'll be finer than regular grind.
Beware of substitutions that include demerara sugar. The crystals are larger than granulated sugar, so the purpose is defeated. And using brown sugar in place of caster sugar affects the color and taste of your recipe.
And the next time you make a creme brulee or meringue for a Pavlova or French macarons, use caster sugar. There IS a difference.