Originally Posted by dstar26t
If it is in fact DMS, just chill it down to under 185ºF at flameout and then do your hop stand. SMM doesn't convert under 185ºF.
The SMM to DMS conversion does take place under 185* its just slow. The time it takes SMM to convert to DMS at 212 (boiling at sea level) is about 38 minutes, at 185 it would take over 5 hours for that to occur.
My bet is that there is there was a nice amount of DMSO in the grain which yeast convert to DMS, if your unlucky. Or there was condensation falling back into your wort.
If you try it a couple more times and can't get rid of the DMS you can try what budweiser does and 'strip ' the wort by pumping air through the wort as a cools down (looks like you are boiling it). not something I would strongly recommend though. You could also try using CO2 but i don't know if it would do the same thing.
Next time you buy the grain see if you can get the malt specs, see how old the grain is and SMM levels (maybe they'll even have DMSO but its rare)