"Does This Taste Infected?" Dunkelweizen AKA "My Crazy Dunkel"

That whole thing about having everything under control with brewing and thinking we know what's going on?  The part where I said "I feel like we are at the point where we can dependably choose to make a beer that tastes a certain way, and make it so"?  Ignore that.  At least for now.

We set about brewing a Dunkelweizen.  A traditional German wheat beer, with a little dark malt flavor and yeasty profile.  We designed a nice little grain bill that would give us some malt sweetness and a touch of toasty cocoa notes.  We hopped lightly, just to balance the malts.  We chose an appropriate yeast strain that would make some spice and banana notes that appear in the traditional style.  And then everything went to hell.  Somewhere along the line (we think in the temperature critical part of fermentation known as primary) the yeast got out our control and started producing a very tart, lemon juice flavor.  At first I thought the beer might have got infected, but we quickly ruled that out.  Souring bacteria cannot thrive well in beers that are hopped any more than a few IBUs, and there was no pellicle (a visible sign of infection that looks like a white film on your beer) that would indicate another type of bacteria.  As the beer aged, the sour flavor diminished to a point where it was drinkable, but still too tart for the style.  Then we bottled.  After three weeks (which is how long it generally takes to carbonate a beer) is was very sour, dominated by lemon juice like flavor.  I had one recently (5 weeks after bottling) and the sourness has faded a bit but is still present.  I really hope it subsides more.  We learned that you really need to keep your fermentation temperatures in your control.  We hadn't really been paying too much attention here, and were neglecting a couple key elements to the process, and may have been fermenting somewhere between 5 and 10 degrees warmer than we thought.  Although this is likely to be the culprit for our sour lemon beer, it isn't sure.

Here's the recipe:

Beer Name: My Crazy Dunkel
Style: Dunkelweizen
OG: 1.048
FG: 1.008
ABV: 5.3%
IBUS: 16

Grains:
4 lb Wheat Malt
2 lb Pilsner Malt
2 lb Munich Malt
10 oz Chocolate Malt
1 lb 4 oz Rice Hulls

In the Boil:
1 oz Hallertauer Hersbrucker Hops @ 60 Minutes
½ oz Strisselspalt Hops @ 60 Minutes
1 tsp Irish Moss @ 10 Minutes
1 tsp Wyeast Yeast Nutrient @ 10 Minutes

Fermentation:
Wyeast 3056 Bavarian Wheat Blend in primary
Primed with 5.7 oz Amber DME

Brew Notes:
28/05/13: Brewed
Stepped mash
20 Minute Protein rest @ 122F
60 Minute Saccharification rest @ 152F
10 Minute Mash out @ 170F
Fermented in cooler set to regulate to 65F
02/06/13: SG of 1.010, Slight sour flavor. Infection?
05/06/13: SG of 1.010, Racked to secondary. Sourness fading
19/06/13: SG of 1.008, bottled

Tasting Notes:
26/07/13:  Pours cola colored with a thin head that dissipated quickly.  Nose is lemon zest and a touch of dark malt.  Aromas of lemon zest, and a touch of bittersweet chocolate malt as it warms.  Sour on the palate, with the slightest hop bitterness here. Thin body and moderate carbonation.  Sadly one dimensional and possibly infected.  Let it age and pray it gets better.

Either we made some very unhappy yeast, or got ourselves a right nasty Lactobacillus infection that can tolerate the hop level we used (apparently rare but not impossible upon further research), either way this beer was a learning experiment.  We have since bought new equipment for sour beers (Okay, I was working with lacto at the same time we brewed this and cross contamination is a POSSIBLE issue) and are paying more attention to fermentation temps.  Am I going to throw it out? Hell no! Am I going to use this yeast again? Not likely.  Will we be more careful about contamination and temperature control? Yes.  Will I make it right eventually?  You bet.