Diacetyl Perception

There could be more aceto-lactic acid in the beer that is slowly converting to diacetyl as it sits. Warmer temperatures will greatly accelerate this conversion. Heating a sample in a hot water bath for 20 minutes or so, cooling, and then comparing with a cold sample is an easy way to tell how much is left. If you get a strong diacetyl aroma in the heated sample, there is more potential diactyl left to convert and it'll only get worse. It's a tough fix once the her has been chilled.

 

IMO, Shipyard is the poster child for diacetyl. Even more so than Magic Hat.

 

I CAN get some magic hat beers, but generally not a full variety. The stout, IPA on tour, #9, those are commonly available. I have tended to buy the heart of darkness stout more than just once (I think that's the name of it), as I quite like that one. The IPA on tour I pick up when it changes, and I pick up about one sixer of #9 a year, but yeah, I've tried them. Do tell what I am supposed to be noticing, and if it's present in these beers (mostly the stout).

FWIW, I did not think there were "off" flavors in any of magic hat's beers. I just like some more than others, which is reasonable for any brewery.

Otherwise I'm still planning to buy some of that Samuel Smith's, just trying to get a handle on this taste (without buying any tasting kits, lol).

 

Fair enough... I didn't think about locations, and where Shipyard may or may not be available.
I've had Magic Hat on and off for ages - especially the Heart of Darkness, which in it's original form was one of the beers that really got me into craft beer (this would have been about '96, '97 or so.) I also do like the reissue of the HoD they've had the past couple years - it seems lighter than I remember it from back when, but that may be due to palate shift. I have not ever noticed diacetyl in that one, and I think I'm fairly sensitive to it. Some of their IPAs, maybe, but I think they've improved things the past couple years, even those I've tried I don't notice it.
TO me, diacetyl presents as 2 things, the first is a flavor similar to butterscotch, with maybe a touch of Band-Aid there as well. Not usually something I want to see in beers, with the possible exception of some English styles.
Also, there is a mouthfeel involved, also like sucking on a butterscotch candy, you know how it coats the mouth with a sticky film? yeah, kind of like that.
Others feel free to chime in if I didn;t do a good job explaining it.

 

Aceto-lactic acid, at the levels it exists in beer, won't provide any flavor impact. It's the oxidation into diacetyl (accelerated by heat, as with other oxidation reactions) that provides the impact, as diacetyl can be perceptible at under 100ppb, though it varies widely by taster.

 

I second the opinion that you're insensetive to diacetyl. I'm certainly not nearly as sensitive to it as many people, but MH 'IPA's' smell of diacetyl more than hops to me. However, I've not tasted any MH in a couple of years, in which time they have switched ownership and brewers, so it might have improved. Not going to spend any $ to find out though.

 

Well I tried Samuel Smith's organic pale ale today, and I think I now know what diacetyl tastes like. To me it didn't make the beer undrinkable, but it didn't make me want to buy it again either. I have liked certain of their beers, but that particular one I didn't much care for. I suppose it was somewhat butterscotch-ish (but not like I expected, which is like Werther's butterscotch candies). I haven't had this problem in my beers, I'm happy to say.

 

Sometimes (more often?) diacetyl tastes more like movie theater popcorn imitiation butter than like butterscotch.

 

With some beers I get a flavor like diacetyl, but the tell tale for me is slickness on the tongue and in the mouth. My perception level is medium high, but I have no problem getting it in Sam Smiths. Why it is called world class eludes me. A few of their beers are very good, though.

 

It's a feature, not a bug.

 

Bingo on that descriptor, that's the stuff that was in that beer, and I can detect it.

 

I have a keg of lager that seems to have this phantom diacetyl (I like this term). However I used Wyeast 2633 Octoberfest Blend (my WAG is its a blend of their Munich and Bavarian). Anyway I've used the yeast a lot and have had great luck with it. In the past I've never had D problems with it, but I typically always do D rests with a few points left, and I've won a number of ribbons from beers made with this yeast.

So I brewed one beer with it, and it has a low level of Diacetyl that seems to come and go, must be on my threshold. I entered it into a competition recently to see if the judges pick this up (I do not have the results yet). Anyway, I brewed a second batch two weeks later and used the slurry from the first. I did not do a D rest on the second batch, the second batch is perfect, no trace of D. The only thing I narrowed down for the first batch's D issue is possibly slightly under pitching the first batch. I think the yeast was frozen in transport (it was shipped during a cold snap), I made 3L starter on a stir plate for this batch, but it seemed sluggish to me. So I don't think I pitched enough yeast.

Also, I seem to notice that the first beer poured seems to have more noticeable D. If I pour a few, it seems to diminish. Can D drop to the bottom of the keg? Or does it always stay perfectly in solution?

So in a round about way my question is.. Are you sure you pitched plenty of healthy yeast?

 

I think you found your problem. You under pitched the 10 gal batch. I'm guessing at your OG but you probably needed about 700B to 800B cells for that batch. A 1 gal starter would only be about 400B and that assumes a stir plate. Unless you mean 1 gal of slurry, in that case you pitched plenty.

 

Yeah, diacetyl is a bugger. It haunts me because it can be so difficult to figure out where it's coming from. It can come from so many places.

Have you tried a forced diacetyl test with the Pilsner? I've never tried the microwave test. I've always done it this way.. http://www.professorbeer.com/articles/diacetyl.html its at the bottom of the page.

This last batch bugs me because I thought I did everything right. I guess I have to start counting yeast cells now.

 

ETA? Explain the acronym?