Our flavour are stable from microbiological point of view if they are stored in a dark-cool and ventilated area and in sealed drum.
If the drum is abnormally inflated (due to bacteria/moulds/yeast growth)
Globally speaking, as far as the taste itself is concerned, we do recommend to compare an incriminated lot with on one hand the last lot received before that one and on the other hand a freshly weighed formulation. Loss of strength, appearance of off-notes (such as oxidized ones or any unpleasant ones) could lead you to consider that the profile of your flavor significantly changed for some reasons. As far its bacteriological stability is concerned, an inflated drum could be as a matter of fact a critical sign.