The primary difference between the two common forms of icing sugar – pure icing sugar and icing sugar mixture – lies in the addition of cornflour to the latter. Icing sugar mixture contains a small amount of cornflour, which helps prevent it from clumping and forming lumps when exposed to moisture. Pure icing sugar, as its name suggests, is 100% powdered sugar without this additive.
Understanding Icing Sugar Varieties
While you might see "icing sugar" referred to broadly, it's important to understand that it typically comes in two distinct types in many markets:
- Pure Icing Sugar: This is finely ground granulated sugar, typically with no other ingredients. It's known for its smooth texture and intense sweetness.
- Icing Sugar Mixture: This is also finely ground sugar, but it has a small percentage of anti-caking agent, usually cornflour (corn starch), blended in. This addition is specifically designed to improve its stability and ease of use.
The Key Difference: Cornflour Content
The cornflour in icing sugar mixture serves a crucial purpose: it acts as an anti-caking agent. Sugar is naturally hygroscopic, meaning it readily absorbs moisture from the air. When it does, sugar crystals tend to stick together, forming hard lumps. The added cornflour absorbs this moisture, keeping the sugar free-flowing and preventing clumping.
Here's a quick comparison:
| Feature | Pure Icing Sugar | Icing Sugar Mixture |
|---|---|---|
| Composition | 100% finely ground sugar | Finely ground sugar + a little cornflour |
| Lump Prevention | Prone to lumping if exposed to moisture | Less prone to lumping due to cornflour |
| Texture/Feel | Very smooth, can feel slightly gritty if not fully dissolved | Often feels silkier, less prone to hardness |
| Best For | Traditional icings, frostings, meringues, delicate glazes where pure sugar is preferred | General baking, dusting, simple icings, where anti-caking is beneficial |
When to Use Which Type
Generally, if a recipe doesn't specify which type of icing sugar to use, it often doesn't significantly matter which one you choose for most applications. However, understanding their differences can guide your decision for optimal results.
- For recipes requiring a perfectly clear or pure sugar finish:
- Pure icing sugar is often preferred for things like delicate glazes, certain types of meringues, or if you're making specific candies where any cloudiness from cornflour is undesirable.
- It's ideal when you want the sugar to dissolve completely without any residual powdery feel that cornflour might subtly impart (though this is rarely an issue).
- For everyday convenience and anti-lumping properties:
- Icing sugar mixture is highly versatile and widely used for dusting baked goods, making buttercreams, simple icings, and frostings.
- Its resistance to lumping makes it easier to store and work with, especially in humid environments. This is particularly useful for things like Royal Icing, where smoothness is paramount.
In essence, the choice often comes down to a slight preference in texture, solubility, or simply the convenience of not dealing with lumps, as provided by the cornflour in the mixture.
