Castor sugar, also known as caster sugar or super-fine sugar, isn't easy to track down. If you do manage to find it, you'll also probably find that it costs a bit more than you want to spend. The good news is that it's easy to make.
Castor sugar is really nothing more than granulated sugar that has been ground to a super-fine consistency. If you don't mind doing a little work yourself, you'll spend less.
What Exactly Is Castor Sugar?
It's possible that you've never heard of castor sugar before, and if you look through recipes in cookbooks or on the Internet, you'll probably come across many other kinds of sugar that you never knew existed. It gets even more confusing if you're looking at a recipe from another country because the sugar called for in the recipe may go by a different name, and it may not be available by that name in your local store.
So let's sort some of that out.
Granulated sugar always refers to white sugar in the U.S. It has that somewhat gritty texture. Powdered sugar, also known as confectioner's sugar, is simply granulated sugar that has been ground into a fine powder. Castor sugar is somewhere between the two. It's been ground just enough to take on a super-fine quality, but not a powdery consistency. As long as you keep granulated sugar on hand, you can make powdered or castor sugar as needed.
What is Castor Sugar Used for Anyway?
Castor sugar is used mostly in recipes where the sugar must dissolve or melt easily. Unlike granulated sugar, castor sugar is able to dissolve without heat. You'll often find it in meringue recipes for this reason, and some people use it to sweeten cold drinks and berries.
Of course, you've probably sweetened drinks and berries with regular granulated sugar many times and you've been fine with the results, so castor sugar isn't an absolute must-have ingredient. If you don't feel like going to the trouble of making your own, you can probably get by with granulated sugar. Just know that you'll experience some of that gritty texture that goes hand-in-hand with the granulated variety. Most people won't notice (or care if they do). They'll just be glad you've made something tasty, and are sharing it.
What You'll Need to Make Your Own Castor Sugar
You'll need nothing more than some granulated sugar. The quantity will depend on how much castor sugar you need for your recipe.
How to Make It
Place the granulated sugar in a food processor or blender. Then, pulse it, until it reaches a super-fine, but not powdery consistency. Let the sugar settle for a few minutes. Otherwise, you'll end up with a dust cloud when you open the food processor or blender bowl.
And that's really all there is to it. Use your sugar in place of the castor sugar that's called for in your recipe, and you should get beautiful results. Store any leftovers for the next time you bake. Make sure you label the container. You may know what's in that jar now, but don't count on remembering later.
The granulated sugar might etch your blender pitcher or food processor bowl, particularly if it's made of plastic. You can use a coffee grinder or a spice grinder instead, if this is a concern. Just know that it'll probably take you several batches to make enough for your recipe.
More Specialty Sugars You can Make Yourself
You can also make your own powdered sugar, muscavado sugar, brown sugar, and colored sugar at home. There's no need to spend top dollar for these varieties at the grocery store, or to dedicate a ton of pantry space to storing them. Learn how to make them, so you'll be ready to tackle any recipe that calls for them.
While you may not be able to make some sugars, like demerera or turbinado at home, you can whip up a respectable substitute to take their place in recipes. Tuck these subs in your arsenal now, so you'll be ready for wherever your next baking adventure takes you.