Brew that smells:
The brew smells of rotten eggs:
One possible cause can be from the yeast strain. The hydrogen sulphide scent (rotten egg smell) can have two possible causes which are either the yeast strain or are caused by bacteria. Quite a few Lager yeasts are notorious for producing fair amounts of H2S during the fermentation process. However, the scent as well as the Sulphur taste will disappear during the lagering process. A solution to this will be to allow the beer to lager for an extra few weeks after the primary fermentation has completed.
Now let’s elaborate the second cause, namely bacteria. It is a possibility for infections caused my bacteria to produce sulphurous odors. If a lager is not being brewed, then this is an indication of an infection in your brew. However, it is possible to fix it. Allow the fermentation to run its course and then taste and see if the infection still persists. If it is, then sadly it’s best to throw it away and to start again.