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% | |
