As a response to Bill Mackin's posting on MMD 021018 I would say that
I avoid mold on hide glue by using a very simple method:

After using my hide glue (mostly a small portion out of the vessel)
I put the vessel with the glue in the deep-freeze chest.  There it can
stay over many months without any mold growing up.  Also I could not
find out that the glue would weaken.

I have used this method for more than three years; before I always had
problems with mold on hide glue.

Does anybody know about any disadvantage of this method?

Greetings from Germany
Christian Greinacher