What is the range of temps you will likely see? Organic sounds like trouble. If you cook sugars they caramalize. You would never get the system clean of them again.
How much fluid are you going to need? Propylene glycol is non-toxic (unlike ethylene glycol, which is metabolized into formadehyde).
PG is what most modern animal/environmentally safe automobile atifreeze is made of, but both ethylene and propylene glcol require anti-oxidants and occasional replacement to keep them from corroding the materials the heat transfer system is made of.
Glycerol is also an excellent coolant that is non-toxic.
https://en.wikipedia.org/wiki/Antifreeze