Using the answer space to provide translation of the German government document.
The document is from the Federal Institute for Risk Assessment -
a body under public law of the German federal government with full legal capacity. The institute comes under the portfolio of the Federal Ministry of Food and Agriculture (German: Bundesministeriums für Ernährung und Landwirtschaft, BMEL) and has the task of providing scientific advice to the federal government on issues relating to food safety, product safety, chemical safety, contaminants in the food chain, animal protection and consumer health protection.
Only the relevant section is below, the rest is background info.
For physical reasons, the maximum heating limit of 100 degrees Celsius
(boiling water) cannot be exceeded. The same applies to the so-called
cauldron preserves from domestic and rural slaughter, since here too a
temperature of 100 degrees Celsius is not exceeded during heating. If
you want to preserve meat or vegetables such as beans, you should
always heat the food twice to 100 degrees Celsius within a day or two.
Between the two heating processes, the preserves should ideally be
stored at room temperature. During the first heating, the bacteria
capable of reproduction are killed and the spores can germinate and
develop into bacteria capable of reproduction. These can be killed
with the second heating.
If, despite all precautionary measures,
botulinum toxins have formed during storage, they can be inactivated
by boiling the preserving goods to 100 degrees Celsius immediately
before consumption, as the toxins, unlike the spores, are sensitive to
heat. At a heating temperature of just 80 degrees Celsius, several
minutes are required for inactivation.