An observation on diacetyl.

[Charlie]

diacetyl n. a greenish yellow liquid compound (CH3CO)2 that is chiefly responsible for the odor of butter and contributes to the aroma of coffee and tobacco, and that is used as a flavoring agent in foods (such as margarine)

Two entries at my local club's annual comp last Saturday (style was APA) had a prominent diacetyl flaw.

1. Number "E" (an in joke, you'd have had to be there) had a buttery aroma, and a prominent slickness of tongue. Someone (I think it was BrewMaster) commented on the way the beer oozed down the side of the glass when swirled; kind'a like a high alcohol brew will show "legs", but without the legs (if that makes any sense).

2. Number "B" had almost a butterscotch aroma, and a butterscotch flavor. The flaw was so obvious I forgot to comment on its mouth feel. It also displayed the "leggy without the legs" characteristic when swirled.

This caused BM and me to wonder if the diacetyl "slickness" that you get on the tongue is an actual physical property of a brew contaminated with diacetyl. And if, even at low levels, diacetyl has a viscosity reducing (or oily) characteristic that is responsible for both effects.

Charlie (cross posted from the club's forum)

[BDawg]

Yes, diacetyl often presents a slickness on the tongue, roof of the mouth and behind the teeth. That's one of the indicators I look for when I'm judging and I get butter or butterscotch in the aroma.

HTH-

[Charlie]

Yes, diacetyl often presents a slickness on the tongue, roof of the mouth and behind the teeth.

Yes, but does it cause the leggy (without legs) thing in the glass?

Next time you come across diacetyl take a look. I'm thinking we're onto something here, but would like some confirmation.

Charlie

[ChrisKennedy]

Yes, diacetyl often presents a slickness on the tongue, roof of the mouth and behind the teeth.

Yes, but does it cause the leggy (without legs) thing in the glass?

Next time you come across diacetyl take a look. I'm thinking we're onto something here, but would like some confirmation.

Charlie

No but that protein slime is made by certain bacteria (namely pedio) which also produce diacetyl.

So the diacetyl and slime you saw are likely both caused by the same thing, an infection.

[Charlie]

So the diacetyl and slime you saw are likely both caused by the same thing, an infection.

Aha! I learn something new every day.

Thanks!

Charlie

[scotchpine]

Charlie, you may want to search Sarcina Sickness. AJ pointed me towards that on one of my posts and it's very interesting. I also found it interesting in my case that some of my bottles in that batch were way more pronounced with diacetyl than others, some hardly at all. I suspected that the potential was there in the beer, as I used a whole pound of flaked barley in 5 gal batch, but was triggered by more O2 being introduced while filling some of the bottles. I remember bubbles gathering in my bottling hose durung the second half that I was not able to keep cleared. I have since gone to kegging though.