Performing a diacetyl rest after lagering

After 5-6 weeks in secondary, my Oktoberfest still has a prominent diacetyl flavor. I did a diacetyl rest at 68 degrees for 3 days at the end of primary but I guess it wasn't long enough since this beer tastes like malty popcorn right now. I've read that you can do a diacetyl rest after fermentation by pitching a large amount of healthy yeast and raising the temperature into the 70-75 degree range. Has anyone done this with good results? Will I need to go through an additional lagering phase if I repitch? I'm not competing so I don't care too much about clarity.

I did some research and decided to krausen the beer (like in this link: http://***********/stories/techniques/article/indices/41-lagering/970-kraeusening-techniques ). I made up some wort (about 15% of the total volume of the batch), hopped it to match the IBUs of the beer, and pitched my yeast last night. When it gets to high krausen later today I'm going to dump it in and see what happens.

I've had great luck krausening my beer. I made a butter bomb ESB with 1968 that I krausened and that beer scored very well in a competition just the next week. I actually just made an ordinary bitter with a similar grain bill but lower gravity, and then took a few quarts of that out to krausen the ESB.

Me does the same thing but to save time use a neutral flavored dry yeast.

That Kruesening technique sounds like it might work but in the future waiting until the end of primary is too late. I have heard the rule of thumb is to go with the d-rest when your SG has dropped 2/3 of the way from OG to FG. At any rate I usually do a d-rest at 1.020 or after 1 week of primary, and I have never had a problem with diactyl so it must work OK I guess.

I think the problem was the yeast I used. I went to a different LHBS than I usually go to and he suggested using 2124 Bohemian Lager instead of Oktoberfest (it was the only lager strain he had in stock) and I found out after the fact that this yeast is notorious for making movie popcorn beer. I'll definitely be more discerning with my next lager attempt.

What yeasts have you used that had little to no diacetyl production? I think my next lager will be a hoppy American pils and I definitely don't want butter in that beer.

AviatorTroy said:

That Kruesening technique sounds like it might work but in the future waiting until the end of primary is too late. I have heard the rule of thumb is to go with the d-rest when your SG has dropped 2/3 of the way from OG to FG. At any rate I usually do a d-rest at 1.020 or after 1 week of primary, and I have never had a problem with diactyl so it must work OK I guess.

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I've had it work when I used to secondary ferment. Also I have had traces of diacetyl after reaching my FG which was cleaned up by letting it sleep on the yeast or adding more yeastie-beasties. One could also add a small amount of fermentables when kruesening.

Oh yea, forgot to mention I usually let it go a couple weeks after fermentation is complete before I rack and cold crash to lagering temp. Seems like leaving it sit on the layer of yeast does help clean it up. I am sure as heck no expert, just throwing out there what works for me.

And I am going to try kreusening my next lager as well, just because I never have before and I like to experiment.

Update on this: Krausening the beer worked really well. I added actively fermenting wort (about 17% of the total volume) and let it sit on the yeast cake at room temperature for a few days. When I pulled a sample yesterday there was no detectable level of diacetyl in the flavor or aroma. I put it back in the fermentation chamber and I'm going to lower the temperature to 50ish and let it drop clear again and bottle it. Thanks for your help, everyone!