Cornstarch Basics

• Fine and powdery, cornstarch is derived from the endosperm of corn. Gluten-free, cornstarch is used primarily in cooking as a thickener for gravies, sauces and fruit pie fillings. Quick-thickening and neutral-tasting, cornstarch produces a clear, thickened liquid without the use of heat. Because cornstarch is prone to clumping when added to hot liquids, it is important to mix it with a cool liquid first before adding it to a hot liquid. Avoid over-stirring and extended cooking with cornstarch, as it can lessen its thickening power.

Cornstarch Shelf Life

• Cornstarch will last indefinitely beyond its printed best-by date. Because improper storage is the only way to ruin cornstarch, it's important you store it correctly. Store cornstarch in a cool, dry area, away from moisture. Avoid storing cornstarch next to appliances that produce ambient heat, such as a refrigerator, stove or dishwasher. Keep cornstarch in its original packaging with the top in place for the best results.

Cornstarch Spoilage

• The only way that cornstarch can become spoiled is if it gets wet or has moisture introduced from steam or high humidity. When cornstarch gets wet, the starch molecules bond with the hydrogen molecules and will absorb the water. Cornstarch with water introduced will create a cloudy, then thickened and translucent gelled liquid. Once water is added to cornstarch, it is no longer suitable for use. Discard any cornstarch that has gotten wet, as it will not work properly.

Substitutes for Spoiled Cornstarch

• If you are cooking and realize your cornstarch is unusable, don't worry, you can use other items in your pantry to thicken your dish. For each 1 tablespoon of cornstarch called for in a recipe, use 2 tablespoons all-purpose flour or granulated tapioca, or 1 tablespoon of arrowroot powder or potato starch. Measure the ingredients carefully to ensure your sauce, gravy or soup thicken correctly.