Tons of Diacetyl in Maibock using W-34/70

[jtwilliams31]

First time brewing a high-gravity lager: a 1.064 OG Maibock that's currently been fermenting for two weeks, pitched W-34/70 (admittedly only a pack in 3.5 gallons of wort and I don't think it was super fresh), and is currently at 1.010. Great attenuation, but unfortunately there's a ton of diacetyl. I raised the temp to the mid 60's for a bit, but I'm thinking perhaps the yeast wasn't healthy enough and that created the diacetyl? Will raising the temp a bit higher have a noticeable effect? It currently tastes like buttered popcorn so any reduction would be great.

Edit to say that the beer will be bottled, carbed at 68-70 degrees with corn sugar, and lagered until May. Any chance I could leave it in bottles and the carbonation process will clean up for me? Or perhaps I could add a bit of 1.040 starter wort in hopes that the increased temp and original yeast will clean up for me?

 

[thehaze]

Diacetyl needs to be scrubbed in the fermenter for better results. I assume - that if you believe that a sufficient / efficient diacetyl rest is done at 65F for a bit - you fermented low / cold. In that case, 1 pack was definitely not enough. A diacetyl rest is a process you start when the beer is not yet finished fermenting, so the temperature raise is performed during the course of a few days, ending in a longer periode of time, where the temp. is raised further, to allow the yeast to clean after itself, and finish fermenting - if any available sugars are left. I've never had diacetyl with W-34/70, but then again, I never fermented it lower than 58-60F. Fermentation finished quickly every time, with no sulphurous smells during fermentation, no diacetyl and no extended conditioning. I usually drink lagers when young as they taste like lagers already there.

I would not add more starter wort. I would add more yeast at this point, raise the temp. to 70-72F and give the beer 5-7 days. Maybe more, as long as you are willing to wait for it until May, give it more. What was the recipe and the exact mash temperature? Are you sure that your temps. were good, both mash and fermentation?

 

[jtwilliams31]

Diacetyl needs to be scrubbed in the fermenter for better results. I assume - that if you believe that a sufficient / efficient diacetyl rest is done at 65F for a bit - you fermented low / cold. In that case, 1 pack was definitely not enough. A diacetyl rest is a process you start when the beer is not yet finished fermenting, so the temperature raise is performed during the course of a few days, ending in a longer periode of time, where the temp. is raised further, to allow the yeast to clean after itself, and finish fermenting - if any available sugars are left. I've never had diacetyl with W-34/70, but then again, I never fermented it lower than 58-60F. Fermentation finished quickly every time, with no sulphurous smells during fermentation, no diacetyl and no extended conditioning. I usually drink lagers when young as they taste like lagers already there.

I would not add more starter wort. I would add more yeast at this point, raise the temp. to 70-72F and give the beer 5-7 days. Maybe more, as long as you are willing to wait for it until May, give it more. What was the recipe and the exact mash temperature? Are you sure that your temps. were good, both mash and fermentation?

The recipe was pretty simple: 65% pilsner and 35% Munich, 25 ibu magnum and then 1/2 oz Saaz at 10 min and flame out. Mashed at 152 for 60 mins, batch sparged to get 1.064 with 3.5 gallons after 60 min boil. I agree that I don't think I pitched enough yeast - there was quite a long lag time and it wasn't a very potent fermentation, although it did ferment to around 80% attenuation to where I am now at 1.010/1.011. I believe that I did ferment a bit cold - I ferment lagers in my office that isn't heated and it get's down to mid/low 50's where I ferment. It's worked well with lagers in the past, but this is by far the largest I've done, the others being around 1.044 or so max. I know that there is still quite a bit of yeast in suspension - I could see quite a bit when I took a sample today to check gravity - but I really don't think there's much fermenting left with the beer at 1.010. I've moved the beer to my bottle carbonation room that stays at 68, but with so little fermentable sugar left in the wort, I'm not quite sure what adding more yeast would do? I've read around and have seen people discussing the possibility of krausening with a small starter and some neutral ale yeast - I have some German ale yeast in my fridge - but I'm not quite sure I want to go that route. Then again, I don't want to give the beer another few weeks either and it still has as much diacetyl in it then as it does now.

 

[dmtaylor]

You can bottle it. Diacetyl should disappear completely at cellar temperatures (50-60 F) within about 3-4 weeks in my experience. I've done this dozens of times. Patience.