Demerara sugar
Large, hard, pale-brown crystals that do not dissolve readily — which makes it a topping sugar rather than a baking sugar.
Also called raw sugar (US); turbinado sugar (US); golden granulated (UK); can you bake with demerara sugar (UK)
Demerara is a partially refined cane sugar with a thin film of molasses left on large, hard crystals. It is often shelved beside soft brown sugar and behaves nothing like it.
SOFT BROWN SUGAR is fine-crystalled and moist, with molasses distributed throughout. It creams, it dissolves, and it brings acidity and moisture into a mixture.
DEMERARA is coarse and dry. The crystals resist dissolving, and they are hard enough to survive a bake intact — which is exactly why demerara is used on top of things: a crunchy, glittering crust on a loaf cake or a biscuit that would be lost with any other sugar.
Used INSIDE a mixture it is usually a mistake rather than a substitution. In a creamed cake it does not aerate well and can leave gritty patches; in a shortbread it gives an uneven crunch. Where a formulation is wet enough and cooked long enough to dissolve it — a syrup, a wet fruit cake — it works and contributes a mild toffee note.
Turbinado and most sugars sold as 'raw' are the same class of product under other names.
What changes if it is left out
For a crunchy topping there is no good substitute — every finer sugar dissolves. Inside a mixture, soft brown sugar gives the flavour and behaves far better, which is usually what the recipe wanted.
Follows from the crystal-size and dissolution behaviour described above and from the brown sugar record.
RecordedFollows from evidence recorded elsewhere on BakeHQ
Related
What it does
Flavour contribution
A thin film of molasses on a hard crystal, giving a mild toffee note — and crystals hard enough to survive a bake, which is what it is really for.
Covered in
The sugars, and when the difference matters
Hard crystals that survive a bake, which is what makes it a topping sugar.
Compared in
One side of the comparison.
Two brown sugars that got there by opposite routes, and why the difference shows up as moisture rather than colour.
Keep reading
Every ingredient, by what it does
Grouped by function rather than by shelf, so a substitution question has somewhere to start.