fermentation smells like cooked corn

[b2harless]

I have a mosaic IPA in fermentation. the first week plus of fermentation, it had a cooked corn smell. now three plus weeks in, the corn smell has subsided so i'm not too worried about it, i would just like to hear some explanation or similar experiences. the yeast is a 1056 cake that i racked on top of from another IPA (centennial, cascade, columbus). the yeast cake had about and inch of beer covering it and was in the carboy for about 3-4 weeks before i racked this batch on top. the grain bill is simple, 10# 2-ro2, 1# Crystal 60. 1oz cascade for bittering and another 3oz mosaic throughout the boil. fermented at 70-72 degrees during the 1 day lag time then moved to basement where is fermented out at 68 degrees.

 

[Pratzie]

perfectly normal, its DMS. Extend your boil next time to 90 minutes or more and it shouldn't happen again.

http://www.picobrewery.com/askarchive/dms.htm

 

[b2harless]

Thanks, why was I thinking dms smell was more of a sulphur smell?

 

[JordanKnudson]

Yep, "cooked corn" is the most common description of the taste/aroma of DMS (dimethyl sulfide). The precursor for DMS, called SMM, is naturally found in malt, and converts to DMS at higher temperatures.

We count on the movement of the boil to drive off DMS once it is created, so lengthening your boil should drive more of it off. If you're smelling cooked corn out of the primary, it means that fermentation is scrubbing some DMS away as well. My only worry there would be that since the fermentor is presumably covered, some of it might not be able to escape and end of falling back into the beer.

 

[Pratzie]

Eggs/sulfur are also referred to as the chemical name of hydrogen sulfide and are yeast related. DMS being Dimethyl Sulfide which deals with the malt.

You can prevent the DMS/Corn smell, the sulfur smell is just a byproduct of the fermentation and its something you just deal with. But you prob just confused the names since they are similar