These are field notes from my Advanced Cicerone studies. (Yes, I passed!)
Why is DMS Acceptable in a Pilsner?
The mild corn-like aroma on a pilsner has nothing to do with corn in the beer (although some may contain corn to lighten the body and mouthfeel). Dimethyl sulfide, referred to as DMS can be formed on the hot side of the brewing process or as a result of an infection in fermented beer. DMS from an infection is never acceptable, not even in pilsner. Today, I’m focusing on the DMS that can be formed even when beer is brewed properly.
DMS is formed from a “precursor” compound SMM (S-methylmethionine). SMM is found in malt but it is burned-off almost completely during the kilning process. Since very light malt like pilsner is kilned for such a short amount of time, some SMM may remain in the malt after it’s kilned.
Since pilsners are made of - you guessed it - almost 100% pilsner malt they are very susceptible to DMS, even after careful brewing. The best way to eliminate DMS is to boil the wort for a long time and cool the wort extremely quickly after the boil. Since some traditional methods and technologies do not allow for this accelerated cooling, DMS is considered acceptable in pilsners especially the traditional German styles.
So if you’re hanging at the German bar for Oktoberfest this month and you catch a whiff of creamed-corn (the tell-tale sign of DMS formed in brewing) don’t cry “bad beer” right away! Take a few sips, let the beer warm and see if you can enjoy a corny tinge to a classic style.