Examples are: ethanol, lactic acid, butyric acid, acetic acid, acetone, fumaric acid.

The bubbles are carbon dioxide gas. In ethanol fermentation, that is fermentation of wine, beer or other hardy spirits, the equation works as such:

C6H12O6 → 2 C2H5OH + 2 CO2

or

Glucose → 2 Ethanol + 2 Carbon dioxide

Another possibility is the production of hydrogen gas in butyric acid fermentation. That would be the fermentation of cheese.

The Sea Shepard's use butyric acid. Butyric acid is found in butter, parmesan cheese, vomit, and as a product of anaerobic fermentation (including in the colon and as body odor). It has an unpleasant smell and acrid taste, with a sweetish aftertaste (similar to ether). ChaCha!

butyric acid

butyric acid is more polar