Jello is a lunchbox favorite, and a standard summer snack. But, how long does this treat really last? Can you still eat the remainder of that tray of Jello after the block party? Can Jello go bad, and how should it be stored?

Can Jello Go Bad?

Like almost all foods, Jello can go bad. That wiggly, delicious childhood treat contains enough water to make spoilage inevitable. Typically, prepared Jello will last about seven to ten days in the refrigerator.

Pre-packaged jello cups that are completely sealed will last longer. At room temperature, so long as the package indicates that the Jello cup can be stored out of refrigeration, these snack cups can last for three to four months. If the cups are refrigerated and sealed, they can stay safe to eat beyond a year. No chance of them going bad in a lunch box! Once the Jello cups are opened, their shelf life drops to about a week, as with Jello prepared at home.

Dry, sealed Jello mix is another story altogether. Unopened, dry Jello mix can last indefinitely at room temperature. Once the package has been opened, the mix will only last for three months, so if a recipe only calls for a little bit of Jello mix, you’ve still got some time to use the rest of the package!

Image used under Creative Commons from Steven Depolo

How to Store Jello

Sealed Jello cups can be stored at room temperature, or in the refrigerator. In either case, the cups should be kept out of direct sunlight, and away from heat or water sources. Once Jello cups are opened, they should be covered in plastic wrap, and stored in the refrigerator.

Dry Jello mix should always be stored at room temperature, and kept away from light, heat and moisture. Be sure the package stays tightly sealed, to avoid exposure to moisture. Refrigerating dry mix will not extend the shelf life, and the high humidity could affect the quality of the the powder, even causing spoilage. Therefore, refrigerating packages of Jello mix is strongly discouraged.

Prepared Jello should be stored in an airtight container in the refrigerator, or at the very least covered in plastic wrap to keep out air and moisture.

Can You Freeze Jello?

Freezing Jello is not at all recommended. Freezing will break the bonds that hold the gelatin together, causing the Jello to separate upon thawing. The results are a puddle of chunky goop – not exactly appetizing. If you need to speed up the setting process of homemade jello, try adding water with ice cubes, after you’ve dissolved the mix in boiling water. Alternatively, you could chill the Jello down for about a half hour in the freezer, before transferring back to the refrigerator. If you’re going to put the Jello in the freezer, just be sure that the temperature change isn’t too extreme for the container.

Signs that Jello Has Spoiled

Signs that a packet of powdered Jello has spoiled will be pretty obvious. If moisture has gotten in the packet, the powder will be clumpy, and may have even solidified completely. Jello in this state should not be used.

Prepared Jello will start to break down as it ages, and eventually separate. Once you see pools of liquid for on the surface of the Jello, it has spoiled and should not be consumed. Any sour or “off" taste or smell also indicates spoilage.

Finally, mold or bacterial growth means that it’s time to toss that Jello. These growths will show up as white, or dark spots or patches on the surface of the Jello, and could be harmful to consume. Be sure to check the surface of the Jello carefully, as it really presents the perfect environment for bacterial or mold growth.