Castor sugar is simply granulated sugar ground to a fine consistency. The term is used both in the United States and the European Union, in both cases referring to a ground sugar. In the US, caster sugar is also called baker’s sugar, bar sugar, casting sugar, or superfine sugar. Castor sugar is widely available on the internet and in specialty grocery shops but is also easily made by placing granulated (table) sugar in a blender, food processor, or spice grinder and pulsing it until it reaches a fine consistency. Be advised, commercially available caster sugar is significantly more expensive than granulated sugar.
Most people are familiar with granulated sugar (white sugar in the United States), which has a gritty texture and powdered sugar, which is granulated sugar ground into a super fine powder. Castor sugar falls between the two and is ground enough to take on a finer quality that dissolves easily. With granulated sugar, it is possible to make castor sugar or even powdered sugar. Because it does not share the powdery texture of powdered sugar, it does not contain any anti-clumping agents like cornstarch.
Castor sugar is used primarily in recipes that require the sugar to dissolve or melt easily. In fact, castor sugar dissolves without heat and is used by many bars to make or even replace simple syrup and is found in recipes for delicate baked goods like meringues, souffles, and sponge cakes. Its use to sweeten cold drinks is preferred because its fine crystals dissolve well, thus avoiding the gritty texture of granulated sugar in the final product.
If you encounter a recipe calling for caster sugar, regular granulated sugar is often a viable substitute, but you may find the end result to be grainy. In sorbets and fresh fruit, granulated sugar is an effective substitute, but in baking, different sizes of granules often make a huge difference in the final product. Thus we recommend making your own if you either cannot find caster sugar or prefer to save some money.« Back to Glossary Index