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What Is Caster Sugar? FAQ, Recipes, And More

Wondering what is caster sugar? Get to know this underrated sugar variety here! We include a few ideas for how and where to use caster sugar, too!

Caster sugar refers to a type of flaky, super-fine granulated sugar that’s typically made from sugarcane. 

The sweet ingredient is uncommon in the grocery stores in the United States but sought-after in British recipes, especially in the world of baking. 

What’s more, caster sugar (also spelled castor sugar) is versatile. 

Aside from being a great sweetener for mousse, meringue, and sponge cake, it’s also used as a substitute for simple syrup when making shaken drinks or stirred cocktails. 

To learn more about caster sugar, hop on! 

This article explains all you need to know about the condiment, including its uses, substitutes, and differences from other sugar varieties.

What is caster sugar?

Caster sugar is a kind of granulated sugar that’s known for its superfine texture, finer than regular white table sugar, but not as fine (powdery) as…you guessed it…powdered sugar.
Consider caster sugar to be the “flaky sea salt” of the sugar world, but only in appearance. 

If you are familiar with fleur de sel—a salt with a delicate texture and flaky consistency—caster sugar LOOKS like that, but tastes sweet.

Caster sugar can’t be replaced one for one with any other sugar: it is not powdered sugar, icing sugar, confectioner’s sugar, brown sugar, turbinado sugar, white sugar, raw sugar, or pearl sugar.

It is denser and grainier than powdered, confectioners’ or icing sugar, so you may not be rolling your wedding cookies in it, or shaking a sifter of it over your crepes. (Usually, anyway.)

Caster sugar is flakier and more lightweight than table (white) sugar, so ounce for ounce, it will perform differently in and on baked goods. It melts and dissolves faster than table sugar but not as fast as powdered sugar. 

Just like white sugar, caster sugar is specifically made from sugarcane and features that notable sweet taste. 

Think of it also like each grain of caster sugar is medium setting between powdered sugar and white table sugar, but looks flaky, like fleur de sel.

Unlike table sugar, caster is considered rare in the grocery stores in the United States making it more pricey than those which are more widely available.

But flavor-wise, caster sugar flavor is quite similar to white or powdered sugar. And as per caster sugar texture, it has a fine, flaky consistency perfect for topping and garnishing baked goods. 

Caster sugar is sometimes called superfine sugar, casting sugar, and baking sugar as the ingredient is often used in making sweet treats like mousses, meringues, and cakes. 

At King Arthur, they call it Baker’s Special Sugar. 

Over at C&H, they call caster sugar Baker’s Sugar: Ultrafine Pure Cane Sugar

We hear that in Canada, another name for caster/castor sugar is fruit sugar. Huh. We learn something new every day.

So depending on where you look, it can be called a variety of names.

If you’re lucky enough to spot caster sugar in your nearby grocery store, you’ll notice that it comes in two varieties: white (regular) and golden.

How is golden caster sugar different?

While still flaky like white caster sugar, golden caster sugar is less processed, retaining small amounts of molasses that are similar to brown sugar. Due to this, the golden variety is warmer and offers a more caramel-like flavor profile than the regular caster sugar.

What is caster sugar made of?

Caster sugar is made by pulverizing granulated sugarcane into finer snowflake-like crystals, but not so much that it becomes powdered.

You can create your homemade caster sugar by grinding granulated sugar in a food processor or coffee grinder until the crystals turn into a fine grain. 

While caster sugar is sometimes spelled castor sugar, it is not derived from the castor plant, like castor oil is. 

How is caster sugar used?

Caster sugar is a versatile kitchen staple that’s ideal for sweet dishes and even beverages—thanks to its pleasant melt-in-the-mouth textural nuance. 

Per Bob’s Red Mill blog, caster sugar melts faster and can help make baked goods taste lighter. 

They recommend if the recipe calls for caster to use it instead of finding a substitute, for best results.

Here are some creative uses for caster sugar: 

Caster sugar vs granulated sugar

The main difference between caster sugar and granulated sugar or white sugar is their texture. Granulated sugar is somewhat gritty in texture and has a larger grain than caster sugar. 

Some chefs use the two ingredients interchangeably, but white sugar doesn’t dissolve in liquids or batter as quickly as the caster. When it comes to taste, both are sweet. 

When measuring out one type vs. the other, though, consider that caster sugar weighs about 225g per cup while granulated (white table) sugar is about 200g per cup. 

So if you try measuring out 1:1, your food may be more sweet cup for cup when using caster. (Finer grains mean less space between each grain of sugar, hence more sugar in the same space.)

Caster sugar vs confectioners’ sugar

Confectioner’s sugar and caster sugar are types of granulated sugar but the two aren’t always interchangeable. 

Confectioners’ sugar, also known as powdered sugar or icing sugar, is made by finely pounding (pulverizing) granulated sugar into a powder-like texture.

It features a small amount of cornstarch to prevent the substance from clumping together. Plus it has the same sweet taste. 

Again, less space between the sugar grains means that a cup of powdered sugar will be sweeter than a cup of caster sugar.

Caster sugar substitutes

Caster sugar is popular in professional baking and all across Europe. However, many people in U.S. homes may not have it on hand. 

To avoid this dilemma, look for reliable substitutes!

Whether you’re in a pinch or would simply want to experiment with other sugar varieties, here are some substitutes for caster sugar:

Granulated sugar

Caster sugar is a kind of granulated sugar so obviously, the ingredient can usually be substituted with the white sugar in a 1:1 ratio. But caster sugar WEIGHS more than table sugar, so a cup of granulated (white table) sugar will taste LESS sweet than a cup of caster sugar. 

But keep in mind that you may not achieve the exact result when using regular white sugar in your recipes that call for caster. 

Also, it’s worth noting that you may notice a flecked appearance or a crunch in the final product due to the undissolved sugar crystals. 

In drinks, it is best to use a simple syrup instead of granulated sugar, because the table sugar grains fall to the bottom of the glass, especially in cold drinks. 

You can also make your own version of the caster sugar by grinding granulated sugar in a food processor, mortar and pestle, or clean coffee grinder.

Raw sugar

Raw sugar, like demerara sugar or turbinado sugar, is a great substitute for golden caster sugar. 

Due to its similar flavor profile to caster, you can use raw sugar in place of the original ingredient in a 1:1 ratio. 

For best results, consider grinding the raw sugar to make the crystals smaller.

The bottom line

Caster sugar is a staple in the U.K. baking world. 

Thanks to its distinctive taste, texture, and versatility, the possibilities are endless when using the ingredient in various dishes and drinks.

If you’ve never tried to experiment with caster sugar in any of your baking adventures, then you’re missing out big time! 

Now is the time to choose a few recipes I’ve mentioned above and start creating your own version at home for everyone!

Want to find out if brown sugar goes bad? Learn more here.

How To Make Homemade Caster Sugar

How To Make Homemade Caster Sugar

Learn how to make your own caster sugar at home when you're in a pinch.

Ingredients

  • Granulated white table sugar
  • Food processor (or mortar and pestle)

Instructions

  1. Pour granulated sugar into a food processor, a cup at a time.
  2. Pulse the sugar and scrape down the sides.
  3. Be careful not to over-process or you will end up with powdered sugar. 
  4. If using a mortar and pestle, start with a small amount and hand-grind until it reaches your desired consistency.

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