Why You Shouldn't Freeze Anything With Cornstarch

Cornstarch has long been a cook's not-so-secret weapon, thanks to its incredible thickening properties. According to Bob's Red Mill, cornstarch is made up of a bunch of sponge-like molecules that grow and expand when heated. While it can't be added directly to a dish without clumping, you can easily mix it into a slurry with some water to make any meal a bit more hearty. You can find it in a variety of ingredient lists (we're particularly fond of the magic it works on homemade custard), but most recipes neglect to mention one important detail: You shouldn't freeze anything made with cornstarch!

"Why?" you ask? According to The Old Farmer's Almanac, the thickening agent loses its touch once frozen, since thawing it out turns foods and sauces spongy. If you're big into meal prep, then don't worry – there's still hope for your frozen sauces! There are plenty of other thickening agents that you can sub for cornstarch if you're hoping to cook ahead and freeze some meals.

Use a different thickening agent if you might freeze your leftovers

Flour is one of the most popular choices to thicken up a recipe since it lends to a great roux, which Taste of Home defines as a "cooked combination of flour and fat." Mix some flour with butter and let it simmer in your dish for hours on end; it's the perfect solution to meal prepping beef stew, and flour works great alongside dairy. The outlet notes that there are just a few catches: It's not a perfect 1-to-1 substitute for cornstarch since it won't thicken as well, so be sure to use double the amount of flour, and it will likely cloud up your sauce.

Depending on the recipe, you may want to swap cornstarch for arrowroot instead. It's ideal for bulk cooking since it isn't affected by freezing, so you won't get the separated texture that thawed cornstarch produces (via Cook's Info). Just skip the arrowroot when it comes to dairy-based dishes. It may get slimy and ruin your gravy, turning your Sunday spent meal prepping into a total waste of time.

That being said, arrowroot gives sauces a glossy shine just like cornstarch does, making it a great addition to fresh jam fillings and stir fry dishes. Even better? It's an effortless, 1-to-1 swap with cornstarch, so you don't have to do any wacky recipe math equations mid-meal prep (via Epicurious).