Attempted a cream ale/lager and had an odd result, opinions?

[Fly_Rodder]

Background:
10 gal three vessel e-system, batch sparge from coolers

Fermentation is completed in my basement and temp in the cool room can be as low as 55F in the winter months. I've seen some suggestions that a plastic fermenter on the concrete slab can maintain temps for lager yeast fermentation (the concrete being a giant heat sink). So, I decided to take a swing at a lager this spring.

Recipe
17 March 2013
Boil Size: 13.98 gal
Post Boil Volume: 12.48 gal
Batch Size (fermenter): 11.00 gal
Bottling Volume: 10.00 gal
Estimated OG: 1.049 SG
Estimated Color: 4.0 SRM
Estimated IBU: 18.3 IBUs
Brewhouse Efficiency: 72.00 %
Est Mash Efficiency: 79.2 %
Boil Time: 60 Minutes

Ingredients:
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Amt Name
12 lbs Pale Malt (2 Row) US (2.0 SRM)
3 lbs 8.0 oz Corn, Flaked (1.3 SRM)
2 lbs Rye Malt (4.7 SRM)
1 lbs Cara-Pils/Dextrine (2.0 SRM)
1 lbs Caramel/Crystal Malt - 10L (10.0 SRM)
1 lbs Corn Sugar (Dextrose) (0.0 SRM)
1.00 oz Perle [7.80 %] - Boil 60.0 min
1.00 Items Whirlfloc Tablet (Boil 15.0 mins)
1.00 oz Santiam [6.10 %] - Boil 15.0 min
3.0 pkg SafLager West European Lager (DCL/Fermen Yeast

Mash Schedule: Single Infusion, Light Body, No Mash Out
Total Grain Weight: 20 lbs 8.0 oz
----------------------------
Name Description Step Temperat Step Time
Mash In Add 28.01 qt of water at 165.4 F 150.0 F 75 min

Sparge: Batch sparge with 3 steps (Drain mash tun, , 4.78gal, 4.78gal) of 168.0 F water
Notes:
------
Mash Temp @ 150F at 25 min remaining.
Corn sugar added with 10 minutes remaining in boil
Chilled to 60F and pitched 400ml yeast slurry into each batch (3 packages dried S-23 and 600ml water)
Starting Gravity @ 1.052 very clear pale gold.
Fermentation began within 12 hours (heavy foam top), airlock activity within 24 hours. Floor temp in cellar @54F, fermenter temp strips read 56F.

Here's where it gets interesting, I think.
FG (1.006) measured on 18 June 2013 and kegged. I was planning on kegging sooner, but things got busy and I figured that it couldn't hurt to stay in the primary a little longer (longer turning into 3 months). Both kegs were purged with C02. The first keg was placed in the keezer and forced carbed over 1 week. 5 ounces priming sugar was added to the 2nd keg and left in the basement (temps in the basement had increased to 63F at this point).

The force carbed keg tasted awful. Bright green apple/peary flavors. I was a little disappointed in my experiment and decided to let it sit in the keezer a while longer before tasting again. Three weeks later, and it was still peary/appley. I was planning on dumping and took it out. Just out of curiousity, I put the naturally carbed keg in the keezer and let it settle and come to temp (38F) over three days (7/11-13).

It tasted delicious. No green apple, no pear, nothing but clean dry lager goodness. So, is it the naturally carbonation refermentation that cleaned up the off-flavors or could it be just getting it off the yeast cake for a month? I'm leaning towards the natural carbing process, but it surprised me that the two kegs could taste so differently.

(Note: I know that this isn't a fully temp-controlled lagering process, but it's a bit of a hybrid and an experiment. If I can replicate the flavor of the second keg, then this is something I will repeat again and again).

 

[adamc]

Sounds like a dirty keg and an infection to me.

Yum.

 

[DrunkleJon]

I had the same kind of problem with my batch of cream ale. My first keg was delicious, the second one developed an apple-y flavor. It was drinkable, but I made sure to thoroughly clean the keg and replace the O rings after killing it.

 

[winvarin]

Could be an infection, but green apples scream acetaldehyde to me. I think the fact that the naturally carbed keg was fine would point me to your initial conclusion. The beer was not quite done when you packaged it. The active yeast in the naturally carbed keg scrubbed the acetaldehyde for you.

If you can spare keeping a keg out of rotation for a bit, try backing the pressure down on the force carbed keg and leaving it at room temp a couple of weeks. Depending on how long you had it cold and how much yeast you pulled out when sampling, there might be enough left to scrub up the beer.

If not, you still have 5 gallons of good beer and a valuable lesson. When I first started temp controlling my beers, I got bit with acetaldehyde a few times. Yeast work more slowly as the temperature drops. You have to account for that an give them time to do their thing.

 

[m3n00b]

Could be an infection, but green apples scream acetaldehyde to me. I think the fact that the naturally carbed keg was fine would point me to your initial conclusion. The beer was not quite done when you packaged it. The active yeast in the naturally carbed keg scrubbed the acetaldehyde for you.

If you can spare keeping a keg out of rotation for a bit, try backing the pressure down on the force carbed keg and leaving it at room temp a couple of weeks. Depending on how long you had it cold and how much yeast you pulled out when sampling, there might be enough left to scrub up the beer.

If not, you still have 5 gallons of good beer and a valuable lesson. When I first started temp controlling my beers, I got bit with acetaldehyde a few times. Yeast work more slowly as the temperature drops. You have to account for that an give them time to do their thing.

Bingo. That's what I was thinking.