Arrowroot and cornstarch are both fine, flavorless starches used to thicken sauces, soups, and pies, but they behave differently under heat, acid, and freezing. Arrowroot produces a glossy, clear gel that freezes well and works with acidic ingredients, while cornstarch gives a sturdy, opaque set that holds up to prolonged cooking. This guide explains the differences and shows you how to swap one for the other in any recipe without ruining the texture.
Ingredients
- For a cornstarch slurry: 1 tablespoon (8 g) cornstarch + 2 tablespoons (30 ml) cold water
- For an arrowroot slurry: 2 teaspoons (6 g) arrowroot powder + 2 tablespoons (30 ml) cold water
- 1 cup (240 ml) liquid to be thickened (broth, juice, or milk)
- Salt and pepper to taste (optional)
Instructions
- In a small bowl, whisk the starch with the cold water until completely smooth. No lumps should remain.
- Bring the liquid you want to thicken to a gentle simmer in a saucepan over medium heat.
- Whisk the slurry again (it settles quickly), then pour it into the simmering liquid in a steady stream while whisking constantly.
- Continue whisking and cook for 1–2 minutes for arrowroot, or 2–3 minutes for cornstarch, until the liquid thickens and turns glossy. Do not boil cornstarch vigorously for more than a minute or it may thin out.
- Season with salt and pepper if using, and serve immediately. For a pie filling, let it cool completely to set.
Tips
- Always mix starch with cold liquid first—never add dry starch directly to hot liquid, or you will get lumps.
- For acidic liquids like lemon juice or vinegar, choose arrowroot; cornstarch can break down and lose thickness in high-acid environments.
- For dairy-based sauces, cornstarch is more reliable because arrowroot can turn slimy when mixed with milk or cream.
- If you need to freeze a dish, arrowroot is the better choice—cornstarch-thickened mixtures often become spongy after thawing.
Serving Suggestions
Use this thickening technique for fruit pie fillings (arrowroot for clear, shiny results), gravies (cornstarch for a rich, opaque finish), stir-fry sauces (arrowroot for a light glaze), or puddings (cornstarch for a firm set). Serve immediately for sauces, or cool completely for pies and puddings.
Variations
- For a gluten-free flour blend: use 1.5 tablespoons (12 g) arrowroot or cornstarch per 1 cup (240 ml) liquid to replace 2 tablespoons (16 g) wheat flour.
- For a keto-friendly thickener: use xanthan gum (1/4 teaspoon per cup), but sprinkle it in while blending to avoid clumps.
- For a clear fruit glaze: use arrowroot with fruit juice and sugar, then brush over tarts.
- For a crispy coating: use cornstarch alone on chicken or tofu before frying—it creates a lighter crust than flour.
Storage and Reheating
Store both starches in airtight containers in a cool, dry place for up to 2 years. Once a sauce or gravy is thickened, refrigerate it in a covered container for up to 3 days. Reheat gently over low heat, adding a splash of liquid if it has thickened too much. Do not freeze cornstarch-thickened dishes, as they will separate; arrowroot-thickened dishes freeze well for up to 3 months.
Frequently Asked Questions
Can I substitute arrowroot for cornstarch 1:1? No. Arrowroot is more potent, so use about 2 teaspoons of arrowroot for every 1 tablespoon of cornstarch. If you use equal amounts, the dish may be too thick and slightly gummy.
Why did my cornstarch sauce turn cloudy? Cornstarch naturally produces an opaque, milky finish. That is normal—if you want a clear sauce, use arrowroot instead.
Can I use arrowroot in a cheese sauce? It is not recommended. Arrowroot can become stringy and slimy with dairy. Use cornstarch or a roux for cheese sauces.
How do I fix a sauce that is too thick? Whisk in a little warm water or broth, a tablespoon at a time, until it reaches the desired consistency. Do not add more starch.
Does acid affect cornstarch? Yes, high-acid ingredients like lemon juice or tomatoes can break down cornstarch, causing the sauce to thin. Arrowroot is acid-stable and a better choice for those recipes.
Can I use these starches for gluten-free baking? Yes, both are naturally gluten-free. In baking, they are often combined with other flours to improve texture; use them as a partial replacement for wheat flour in a gluten-free blend.
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