A fine white starch extracted from maize, corn starch is naturally GF, widely available, and one of the most useful thickening and lightening agents in the GF kitchen.
What it is
Corn starch (called cornflour in the UK, Australia, and much of Europe — also sold as Maizena under the branded name) is extracted from the endosperm of maize (Zea mays) kernels. It is pure starch, not a whole-grain flour.
It should not be confused with corn flour or masa harina (in some regional terminologies), which are made from whole dried maize and have very different properties. Corn starch is pure white, superfine, and essentially flavourless.
Maize itself is a naturally gluten-free grain. Corn starch, as a highly processed extract, contains no wheat proteins — but context and manufacturing matter.
Coeliac safety
Corn starch is naturally gluten-free. In most countries with established food labelling, it is produced on dedicated maize-processing lines with minimal cross-contamination risk. However:
- In the UK and Europe, cornflour from major brands (Maizena, McDougalls, etc.) is widely considered safe for coeliacs and often certified.
- In countries where wheat starch is sometimes labelled simply as “cornflour” or where labelling standards differ, always verify the source.
- As always: look for certified GF labelling if you’re uncertain about the manufacturing facility or country of origin.
Wheat starch and corn starch are different products — if a label simply says “starch” without specifying the source, do not assume it’s corn.
Texture & flavour
Corn starch is virtually flavourless. Its job in baking is structural and textural. It lightens the crumb of cakes and biscuits by diluting the protein content of the flour blend — the same principle as “cake flour” in conventional baking.
As a thickener, it produces a clean, glossy gel in sauces and custards. It thickens efficiently at relatively low temperatures, and the results are clear (not cloudy), making it ideal for fruit pie fillings and glossy sauces.
Best uses
- GF flour blends: 15–25% corn starch lightens the crumb noticeably in cakes, shortbread, and biscuits
- Thickening sauces, gravies, soups: the standard go-to; typically 1 tbsp per 250ml of liquid
- Custards and puddings
- Fruit pie fillings: thickens cleanly and holds up to baking
- Crispy coatings: dusting before frying produces a very crispy crust
- Shortbread: a classic corn starch shortbread (petticoat tails style) works beautifully in GF form
HTGF tips
- Always mix corn starch with a small amount of cold liquid before adding to hot liquid — adding it dry directly to a hot pan causes instant lumping.
- It thickens on cooling as well as heating; sauces will thicken further as they cool, so don’t overdo it.
- In GF cake blends, replacing 20% of your rice flour with corn starch makes a noticeable difference to tenderness — try it in your next sponge.
- Corn starch loses thickening power if frozen — not ideal for freezer sauces or soups that you’ll thaw later. Tapioca or arrowroot hold up better.
If you don’t have it
Potato starch substitutes well at 1:1 in most baking applications. Tapioca starch or arrowroot replace it as a thickener at roughly the same ratio. For lightening flour blends, potato starch is the most direct alternative.