[sharg54]

Just finished off a sack of MO and didn't have a problem with diacetyl at all. Stouts Porters and a few English ales and such and they came out fine but than I have been getting into the habit of using larger starters lately. 2 to 5 hours lag time depending on the starter. Rather than just throwing in a single pack or bottle of yeast I'll throw in at least a 1/4 cup or more to start out. If I can time the last ferment right I just dump in the new wort on the old cake.

[majorvices]

Just finished off a sack of MO and didn't have a problem with diacetyl at all. Stouts Porters and a few English ales and such and they came out fine but than I have been getting into the habit of using larger starters lately. 2 to 5 hours lag time depending on the starter. Rather than just throwing in a single pack or bottle of yeast I'll throw in at least a 1/4 cup or more to start out. If I can time the last ferment right I just dump in the new wort on the old cake.

Well, in many English style ales diacetyl is completely acceptable in moderate amounts especially depending on what strain you use. I always get a small amount of diacetyl when I use wlp002, for instance. Diacetyl isn't necessarily a bad thing. It can add mouthfeel and nuance to a beer. Some styles should not have any diacetyl, obviously, but in many English styles it can be very enjoyable in moderate doses. I personally think that MO highlights and compliments the moderate amount of diacetyl created from some strains.

And just to make sure everyone is clear, I am not saying I get diacetyl from using MO and I am not sure the OP was saying that either. I am saying I pick up some faint flavors from MO that remind me of diacetyl. I should also say that I have gone through hundreds of sacks of MO and order it by the pallet now. I have been experimenting with 100% MO American IPAs and they turn out great, I absolutely love them. I am not saying in any way that it is a bad thing, though I have found it can be distracting in some recipes.

Also, I wouldn't really recommend going directly on a yeast cake unless you are going from a low gravity beer to a very high gravity beer. You are better off pitching the "right" amount of yeast rather that overpitching every batch.

[a10t2]

US-05 ale yeast straight from brick (about 13 gms) and, as was mentioned above, I get a character that reminds me of diacetyl. I'm pretty confident it is not diacetyl.

It could be diacetyl. IME US-05 produces some early in fermentation that may or may not clear up, and you under-pitched by a fair amount.

[majorvices]

I didn't underpitch at all. 13 grams per 6 gallon fermenter is spot on for a 1.065 beer. Not sure what you are talking about.

Also, the same thing happens on my 3 bbl set up. When I make my IPA with wlp001 and 50% MO I pick up the flavor. But when I make my Alt, with wlp001 and no MO it is clean as a whistle.

Edit: I see now why you thought I underpicthed, sean. It was a 12 gallon batch but I pitched it in separate carboys, 13 gms each. So the total would have been 26 grams. My bad.

[a10t2]

Edit: I see now why you thought I underpicthed, sean. It was a 12 gallon batch but I pitched it in separate carboys, 13 gms each. So the total would have been 26 grams. My bad.

Ah, I should have figured you would know better. 

I still haven't figured out why we have such a constant struggle with diacetyl from US-05. At this point, I'm just going to give up though. We have a couple 500 g bricks left and once those are gone I'm going to switch to a liquid culture.