Caster Sugar
Ordinary white sugar milled to a finer crystal, and sold as superfine in the United States. The grain size is the whole difference, and it is why a Caipirinha is muddled onto dry sugar rather than built on syrup.
Quick Facts
Flavour Profile
Primary Flavours
Tasting Notes
Clean, neutral sweetness with no colour and no aftertaste: sugar doing only its one job, sweetening a drink without flavouring it.
Storage & Handling
Airtight and dry: a fine grain takes up moisture and clumps faster than granulated.
Shelf Life
Indefinite kept dry.
Usage
Muddled with lime over cachaça in a Caipirinha, which is its defining job, and used anywhere else a drink is sweetened dry rather than with syrup. Shake it long enough to dissolve, or the last mouthful arrives gritty.
Only the Grain Size Changes
Caster sugar is ordinary white sugar milled to a finer crystal. In the United States it goes by superfine, or baker’s sugar. Nothing is added and nothing is taken away; only the grain size changes, and that changes how fast it dissolves.
Icing sugar is a step further again, milled to a powder and cut with a little starch to stop it caking, which makes it a different ingredient rather than simply a finer one.
Why the Caipirinha Wants It
Speed is why it earns a place behind the bar. In a Caipirinha the sugar is muddled straight onto lime and cachaça, with no syrup and little time to melt. A fine grain gives grip to crush the fruit and still dissolves clean, where coarse granulated would leave grit in the glass.
The crystals also work as an abrasive against the peel, tearing at the oil cells in a way a syrup never could. The sugar is doing two jobs at once, which is the argument for muddling on it rather than sweetening afterwards.
Built Dry
Anywhere a drink is built dry rather than with syrup, caster is the safe sugar. It sweetens without colour or flavour of its own, which is exactly what most shaken and muddled drinks want. It carries no molasses, so it will not muddy a glass the way demerara or muscovado would.
Blitzing granulated in a spice grinder for a few seconds produces a workable caster, which is worth knowing when the jar runs out mid-service.
When Syrup Is the Better Answer
Dry sugar is not automatically the more authentic choice. Sugar dissolves slowly in cold liquid, and a shaken drink sweetened with caster will often finish with a little of it still sitting in the bottom of the tin. That means the drink is less sweet than the spec intended, and the next one made the same way is inconsistent with it. Syrup removes the variable entirely, which is why most bars sweeten with it. Caster belongs where the grain is doing mechanical work, and syrup belongs nearly everywhere else.
Top Tips
- Finer grain, faster melt: that is the entire reason to keep caster over granulated behind the bar.
- For a Caipirinha, muddle the sugar with the lime first, so its grit helps crush the fruit and draw the oils.
- No caster to hand? Blitz granulated for a few seconds in a grinder and you have made your own.
Possible Substitutions
- Granulated sugar, given longer to dissolve or blitzed finer first
- Simple syrup, already dissolved
- Powdered sugar at a lighter hand, since it is sweeter by volume
Production Method
Ordinary refined white sugar milled to a finer crystal than granulated but coarser than icing sugar. The smaller grain is the whole point: more surface, so it dissolves faster.
Common Questions
What is caster sugar?
White refined sugar milled to a fine grain, finer than granulated and coarser than icing sugar. Americans call it superfine or baker’s sugar. The smaller crystal dissolves quickly, which is why bartenders reach for it.
Can I use granulated sugar instead of caster sugar in a Caipirinha?
You can, but give it longer to dissolve, muddle harder, or blitz it finer first. Caster melts into the lime and cachaça faster and leaves less grit in the glass.
Is caster sugar the same as simple syrup?
Same sweetness, different form. Caster is dry and dissolves in the drink; simple syrup arrives already dissolved. Muddled drinks like the Caipirinha use the dry sugar for the grip it gives against the lime.
Does caster sugar go off?
Not in any meaningful sense, since sugar is too dry for anything to grow in it. What it does is take up moisture and set into a solid block, and a fine grain does that faster than granulated. Keep it airtight and away from steam.
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Guide by Jerry Can Spirits