Cornstarch is the go-to ingredient for thickening sauces, desserts and puddings. Of course, you probably aren’t making gravy every day, so that box of cornstarch could easily go forgotten. Can cornstarch go bad? How should you store cornstarch to extend its shelf life as long as possible?
What Is Cornstarch?
Cornstarch is the fine, powdery starch derived from kernels of corn. Because this starch expands so much in water, it’s a great way to thicken sauces and puddings without changing the flavor. The fine, powdery nature of cornstarch brings a soft and velvety texture to gravies and desserts alike.
Can Cornstarch Go Bad?
Cornstarch is actually one of those few kitchen items that really won’t go bad! With proper storage, cornstarch actually can last indefinitely. Of course, improper storage can lead to contamination and spoilage, but storing cornstarch is pretty easy, and shouldn’t be a problem.
How to Store Cornstarch
Cornstarch should be stored in an airtight container, away from moisture and contaminants. Stored in this way, cornstarch can pretty much last forever! Many brands of cornstarch now come packaged in plastic containers, which is great for storage. If you happen to purchase cornstarch that still comes in a cardboard container, or a paper bag, it’s best to transfer the cornstarch to a glass jar that will seal tightly.
Image used under Creative Commons from Francis Storr
Refrigerating cornstarch will not really extend the shelf life, and could actually work against you! The humid environment of the refrigerator could introduce too much moisture to the cornstarch, rendering it less useful over time. Storing cornstarch in the freezer could have similar results.
How to Tell If Cornstarch Has Gone Bad
Unless moisture or other contaminants are introduced to cornstarch, it should last indefinitely. Of course, there is still a chance of spoilage if the container is not properly sealed. Moisture will be the number one enemy of the shelf life of cornstarch! Excess moisture can increase the chance of mold growth, but won’t necessarily “deactivate" the cornstarch. Unlike baking soda or powder, cornstarch won’t lose potency with exposure to liquid. If the cornstarch clumps due to excess moisture, simply sift it before the next use. However, if mold starts to grow in the cornstarch, it should no longer be consumed.
Another way that cornstarch could spoil is with an insect infestation. Part of the reason an airtight container is so important is that bugs are drawn to the “all you can eat buffet" appeal of a giant bag of cornstarch! So, like with all grains, sealing the cornstarch tightly is incredibly important. In addition to sealing the container tightly, folk remedies suggest adding bay leaves to a container of grain to repel bugs that are likely to want to get inside. If you see any signs of insects in the cornstarch – including eggs, larvae or full grown insects – the cornstarch should not be consumed.
An even more effective method for eliminating insects and potential mold growth is storing the cornstarch in an airtight container with an oxygen absorber. This will prevent insect eggs from hatching, as well as mold spores from germinating.