Hydrogen sulfide
Hydrogen sulfide (H2S), or "sulfide" is a yeast-derived off flavor. Sulfide aroma and flavor is often described as sulfurous like rotten eggs, "rhino farts", burnt match, or simply "sulfur".
This is one of the most common off flavors that presents in cider and wine. It can also occur in beer and other fermented beverages. In fact, a slight note of sulfide may be acceptable in some styles of lager (beer).
Why is it produced?
How do we prevent it?
How do we get rid of it when it occurs?