Stuck lager (couple of points sg) need advice.

[Nick_D]

So, I've brewed a Helles. All grain 98% pilsner malt with 2% carahell, WLP833 yeast. Currently at 1.014, needs to get to 1.010 - 1.011. I was attempting to follow the traditional 'cold fermentation with conventional storage fermentation schedule, as outlined on Kai's site http://braukaiser.com/wiki/index.php?title=Fermenting_Lagers (See diagram A)

The story/stats: so far.

- 4 gallon batch
-1.052 OG (13.1 brix, uncorrected) , 12.86 °P
- estimated 289 billion yeast cells pitched (stepped up starter) at 43.7 F into oxygenated wort (@ 1 minute at 1 liter/min flow rate)
-Fast ferment test revealed FG 1.010-1.011, 2.84 °P (6.2 brix uncorrected) tested with both hydrometer, and calibrated refractometer (correction factor of 1.019)
-fermentation allowed to free rise to 48.2. Krausen and vigorous fermentation achieved within 24hrs.
-Fermentation @ 48.2 for 5 days, then temperature dropped by 9F each day until reaching 41 F (i.e 48.2 > 47.3 > 46.4 etc). SG at 41 F was 1.013 , 3.33 °P (6.8 brix uncorrected)
- Racked to secondary keg.
- Added Kruasen made from saved wort (1.6 quarts/0.4 gallons)
-continued to drop temp by 9 F per day, until reaching 33 F. This is where I screwed up. Apparently the rate of temp decrease needs to be dramatically slowed once past 37.5 (according to Narziss). I believe I put the yeast to sleep by chilling too fast, and hence the stalled activity.
- In an effort to fix the situation, I allowed the temp to rise back to 48.2, and krausened with a further 0.6 gallons, made from DME. However in hindsight, I definitely overpitched into this krausen, and thus it didn't culture the new, vigorous yeast it should have. Lag time to high krausen in the batch of krausen was less than 12 hours.
-pitched krausen, which had totally flocculated in the secondary within a couple of days, with no change of gravity (now at 1.014 from the two doses of krausen).
- After leaving it for 5 or so days, with no change in gravity, I roused the yeast by racking to a new keg, and swirling the first one to pick up some yeast and raised the temp to 51 F. Again, no change in gravity after 2 days.

So, with all that being said. What would anyone recommend I do? Allow to rise to 65 F or so, and leave there till (hopefully) full attenuation, then drop back down to lagering temps, abandoning the traditional cold lager fermentation schedule? Should I make a fresh starter, and pitch only the yeast, and allow to rise in temp?

Sorry for the long post, but I've tried to put as much info in, to save people having to ask for those details.

Thank you in advance!

 

[jdauria]

I would call it done...1.010-1.011 is at optimal yeast attenuation rates per what ever software or recipe you used. There is no way you will notice any flavor differences at 1.014. 1.011 is 80% apparent attenuation...1.014 is 72%. Recipe called for 39 gravity point drop, you got 36, 92% if the recipe number.

Check out Brulosphy website for some experiments he does where he does 2 batches of beer and due to various issues he sometimes is a few points off, majority of the time the people that do his blind tastes, struggle telling the difference.

 

[wobdee]

I've never done the cold ferment yet but I know a few people who have and I think they pitch a little more yeast that that. A slight under pitch could cause a stuck ferment pretty easily at those lower temps. Your not off by too much tho, I'm usually within 0-2 points of my FFT on my lagers. If it were me I think I would just keg it as is and lager for 6 weeks, it may drop another point or two.

 

[Nick_D]

Thanks for the replies guys.

I have checked out the Bruslosophy site, and am interested in trying the accelerated lager fermentation method. I am keen to really master the traditional method also though.

I have had the beer sitting at 20 C (68 F) for a few days now, and it has dropped to 1.012, and seems to be working slowly still. It is still pretty 'green' so I'm hoping a little longer at this raised temp will clean it up a bit more (Including of course, a good months lagering also). How clean should I expect it to be pre lagering? No nasty esters or jet fusels, Just a bit rough, and a touch of diacetyl currently. The already subtle flavours of the beer are being obscured a bit at this point.

I am now torn as to which method to ferment with my next lagers. This beer was a trial beer to make mistakes on, so I can do some Oktoberfest beers for a party later in the year. A festbier, and Dunkel. I am really keen on succeeding at the traditional cold method, but this has left me lacking in confidence! Although I do know where I went wrong. Dropped temps too fast + probably slightly underpitched for this method.