Friday, August 9, 2013

Mash-up Quick Sour

Over the course of my first three attempts to brew a Berliner weisse, I've learned a few things about brewing quick (i.e., less than 6 months to complete) sour beers—having had to dump two of my first three batches. They weren't poisonous, but they also weren't worth drinking. Sour beer is the one style of beer in which even the most skilled brewers still routinely have to dump batches.

Lesson #1: If you want to make sour beer fast, induce a lactic acid fermentation before alcoholic fermentation. Alcohol seriously inhibits lactic acid bacteria, as do hop acids.

Lesson #2: If you're souring prior to fermentation (and don't have a completely sterile environment), keep the temperature above 110˚F (43˚C), in order to inhibit spoilage bacteria that produce nasty compounds like butyric acid (think vomit, parmesan cheese). Lactobacillus is thermophilic and can handle the heat. Above 115˚F, however, lactic acid bacteria are much slower to produce sourness. Above 140˚F, most bacteria are dead or inactive.

Rather than continuing my attempt to brew a perfect Berliner weisse, I've decided to switch my efforts to attempting the most delicious quick sour I could brew, borrowing techniques from both Belgian and German brewing traditions. My current approach is as follows:

Mash and lauter normally, but instead of boiling the wort, allow to cool to 112˚F (44˚C), then add a handful of crushed 2-row and cover with plastic wrap. Maintain this temperature until the desired level of sourness is reached, sampling daily (2-7 days is a reasonable window). The beer will taste a little bit more sour after most of the sugars have been fermented into alcohol, but it's a minor difference. If the beer starts to smell "off", raise the temperature to 122˚F for 30 minutes. After souring, boil the beer with hops, then cool to 70˚F and pitch your favorite ale yeast. Add fruit if desired after the yeast fermentation is complete.

The main challenge with this technique is keeping the beer at 112˚F. My current set-up consists of an electric heating element and a digital temperature controller, but I've also heard good things about the fermenter heat wraps that homebrew stores sell. If you have little money and much time, intermittent low heat from a stovetop might work. But that would also be a huge waste of energy.

Even though this technique involves spontaneous fermentation, it produces a very clean sour beer. The fact that the beer is boiled after souring also means that almost no bacteria are present in the finished beer, so contaminating your non-sour beers is not a concern. If you want a funkier sour, adding brettanomyces to secondary is always an option, but cross-contamination then becomes a concern again. If you want a sweeter sour, my preferred method is to add a fruit syrup to the glass when serving, as is traditional for Berliner weisse.

Vitals:

OG: 1.056 (pre-souring, pre-boil)
FG: 1.008
ABV: 5%?
IBUs (Tinseth): 15

Water adjustments: 5 grams of calcium chloride
Mash temp: 151F
Mash length: 60 minutes
Efficiency: 75%

Yeast: WLP545
Pitching temp: 70F
Max temp: 71F


Malts Mashed Amount % Max Pts.
2 row 8 74% 36.00
Barley (flaked) 0.75 7% 32.00
English Medium Crystal 2 19% 34.00
Hops/Additions Amount Time AA%
Cascade 0.75 60 6.0%

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