From Cookthink.com
Caster (or castor) [or bakers] sugar is superfine refined sugar. That makes it finer than granulated sugar but not as fine as confectioners [powdered] sugar.I don't have a food processor,or even a blender at the moment, and I did that a couple times in the US, and it just doesn't work as well.
Caster sugar dissolves easily and so is used to give baked goods (especially meringues) a lighter texture.
If you don't have any or can't find caster sugar, you can pulse regular granulated sugar in a food processor to help break down the grains.
I've searched high and low for caster sugar here in Chile so that I could make a meringue, without feeling the texture of normal sugar, but I failed to find any.
So, I did what any logical crazy person would do: I emailed the largest sugar producer in Chile. Turns out, this isn't a product for public consumption.
"Efectivamente, el caster sugar es el producto, pero hace algunos años tuvimos el formato retail de 500 grs. en el mercado, “azúcar fina”, pero nos fue muy muy mal con él. La demanda en Chile de este producto sólo es para la industria de jugos en verdad. Por eso lo discontinuamos. Quizás puedas probar nuestra “azúcar flor” la cual tiene un pequeño componente de antiaglomerante (almidón), que es utilizado en pastelería y en preparación de tragos."
“azúcar fina” = caster sugar
“azúcar flor” = powdered sugar
So, caster sugar is just used for industrial use in Chile (like for powdered juice), and the smallest size they sell is 50kg (110lbs)! The Iansa representative mentioned that they used to sell a 500g (1.1lb) version, but it went "very, very poorly" and they discontinued it.
Alas.
If you find a store with caster sugar, let me know!
