g/4oz caster sugar

Caster sugar, also known as superfine sugar or castor sugar, is a granulated sucrose obtained from sugar cane or sugar beets through crystallization and mechanical processing. The crystals are finer and more uniform than standard granulated sugar, typically measuring 0.3–0.5 mm in diameter. The name derives from its former use in shaker dispensers with perforated tops (casters), which accommodated the smaller grain size. It dissolves more readily than coarse sugar and lacks the molasses content of brown sugars.

Caster sugar is prized for its ability to incorporate into batters and doughs evenly, creating smooth textures without visible granules. It is chemically identical to other white granulated sugars (sucrose), with a neutral, clean sweetness and no discernible flavor beyond sweetness.

Caster sugar is the preferred sweetener in baking, particularly for cakes, cookies, meringues, mousses, and whipped cream where smooth texture and rapid dissolution are essential. It is also used in beverages such as cocktails and cold drinks, where it dissolves quickly without requiring heat. In pastry work, caster sugar is favored for dusting finished desserts and for use in fruit preparations and jams. Its fine granulation makes it superior to coarse sugar in applications where crystalline texture would be undesirable, such as in sponge cakes and custard-based desserts.