Reader’s Question: Cake-in-a-jar — 1 Comment

  1. Hello Jackie
    I read your item on jar cakes. I have not come across them before, but I am inclined to think that they are potentially hazardous if not stored frozen. You say in your last sentence: “I mean you can leave a cake or banana bread out on the counter for days and you don’t get botulism from that…… “.

    The problem is that the jar cakes are not sterilized by the cooking and sealing process. In order to do that you would need to hold the cake at the equivalent of 121C for about 3 minutes. You can’t do that without pressure processing equipment. The spores of Clostridium botulinum can withstand boiling water temperature (100C) for 4 hours. See:

    You can leave a cake on the bench for days without risk of botulism because the organism is a strict anaerobe (grows in the absence of oxygen). Cakes are aerobic. But if you seal them in a jar immediately after cooking, they are anaerobic. The spores germinate, the microorganism grows and at one point in its life cycle produces a deadly neurotoxin.

    Obviously, people like yourself eat jar cakes and there are not hundreds of people dying of botulism, so the risk is not high. However, I would suggest that freezing for storage is a way to ensure safety – Clostridium botulinum cannot grow below about 3C.