Adjusting the Amount

• A powerful thickening agent, 1 tablespoon of cornstarch thickens 1 1/2 to 2 cups of liquid. It might be necessary to increase the amount of cornstarch by 1/4 teaspoon when making a fruit filling and using more sugar than called for in your recipe. Sugar causes fruit to release more of its juices; bumping up the amount of thickener just a bit prevents a runny filling. Frozen berries also require a bit more thickener than fresh ones, because they lose more moisture once thawed. Pies with a peak-a-boo lattice crust require slightly less thickener, because the exposure to heat will cause more of the moisture to evaporate.

Using in Cooked Fillings

• Unlike flour, cornstarch must be blended into a slurry first before adding to hot ingredients. Using a jar with a tight fitting lid, add a tablespoon of cornstarch to an equal amount of cold liquid, and shake until dissolved. Slowly pour this mixture into your pudding, sauce or filling, and stir until thick. Remove from heat and stop stirring once your filling has thickened. Over-stirring puddings or sauces made with cornstarch causes the starch balloons to burst and the sauce to thin. Excess exposure to heat also reduces the thickening power of cornstarch, unlike flour, which benefits from the cooking.

Making Acidic Desserts

• Fillings made with acidic ingredients, such as the lemon juice in meringue pie, have a negative effect on cornstarch. The acid causes the cornstarch to lose its thickening power. To avoid this, thicken your filling with the cornstarch first, before adding the lemon juice or other acidic ingredients. Most recipes for lemon pie call for the lemon juice to be added after the filling has thickened. Acidic ingredients don’t break down fillings or pudding made with cornstarch once they have been thickened.

Storing Baked Goods

• Whether thickened with cornstarch or wheat flour, refrigerate any baked good made with perishable dairy ingredient, such as cream cheese. This includes cookies, cakes or pies with a cream cheese or ricotta cheese filling, even if large amounts of sugar are used. Desserts may be brought to room temperature before serving, but to avoid foodborne illnesses, don’t leave them at room temperature for more than two hours, or one hour on a hot day.