Tannin - Not really. Grape or bark, it's a stable organic.
Fermax - Probably. Di-Ammonium Phosphate and yeast hulls. Di-Ammonium Phosphate breaks down at 158F. Even when exposed to air at room temp, it slowly releases ammonia.
It couldn't hurt to refrigerate both. Make sure they are tightly sealed so they are not exposed to moisture. Over time (A year?, maybe more), both lose their effectivness.