Why Is There Mold In My Jam When I Open It?

There are a couple reasons, but generally what happens is a leak or a problem with the glue band.

Whether it’s a two piece or a single piece lid, they’ll still have a seal band, but a poor seal occurs sometimes. Also, on the top lip of the jar, if there are any imperfection in the glass, or anything that lets atmosphere in and breaks the seal will cause mold over time, even in a standard sugar jam. Generally, that is the reason.

On occasion it is possible to have an unsterile situation if your fill temperature gets too low. To have a sterile pack you must maintain a 190 degree at fill. If you’re unknowingly filling to low, it is possible that it’s not completely sterilized. Even with a sealed lid under vacuum, you could still grow mold or have a bacterial problem. It’s very important to make sure that your pack is sterile and maintaining 190 degrees at fill temperature.