What kind of substance? In any case, I'm very happy with it, the battery lasts a long time.

To the best of my current knowledge, no substance is released during heating.
However, for final clarification, I recommend that you address this enquiry directly to the manufacturer.

One picture shows that food-safe material is used. Should therefore not be a problem. I find the solution with the sensor and ceramic as a heat conductor innovative. Thanks for the information that the battery lasts a long time. Is the temperature correct when heating? We have some problems with the current appliance, which doesn't make life easy with a hungry baby, so we are looking for a working appliance :)

What kind of substance? In any case, I'm very happy with it, the battery lasts a long time.