Kettle Sour Off Flavor

[tagz]

A new brewery in town has been experimenting with small batch Berliners. Both batches I tried had an unpleasant grainy flavor that appears on exhale. Im wondering what off flavor this might be.

Diacetyl is typically characterized as butter but can also be "rancid." DMS can be cooked corn, but also cabbage, mushroom, or nutty. THP can come across as grainy and cereal like but these beers use a commercial lacto pitch and are finished with sacc.

Any thoughts on what chemical might be causing this grainy, musty flavor? I'm wondering if Diacetyl or DMS can appear as grainy at lower levels.

Incidentally, Scott Janish write a great article on DMS. That's what got me thinking. Here's a link:

http://scottjanish.com/how-to-prevent-dms-in-beer/

 

[tagz]

Talked to the brewer today about the process. They mash, bring the wort up to near boiling, cool, pitch lacto, sour, boil for a brief period (15), and finish with kolsch yeast.

Again, the flavor is an unpleasant graininess. Similar to the THP "Cheerios" flavor but maybe a little more musty? It comes on the end of the palate and exhale. It actually has a pleasant lemony tart flavor at the front but the after taste ruins it for me.

I'm mostly curious, so I can identify the off flavor. I'm leaning toward low level DMS, based on the short boil, but it doesn't fit the typical profile. The nutty/mushroom from Scotts article got me thinking.