For my forth batch, I wanted to try something more adventurous. I’ve always liked sour beers, but many of them take 6 to 12 months to ferment… but I heard from a friend about another way to make a sour beer using a starter, and I’d recently had a Leipziger Gose I enjoyed, so I decided to try something in the general Gose vein:
Per Wikipedia:“Gose is a beer style of Leipzig, Germany, brewed with at least 50% of the grain bill being malted wheat. Dominant flavours in Gose include a lemon tartness, a herbal characteristic, and a strong saltiness (the result of either local water sources or added salt). Because of the use of coriander and salt, Gose does not comply with the Reinheitsgebot. It is allowed an exemption on the grounds of being a regional specialty.”
I made the sour starter by leaving about 2 Tbsp of cracked two-row malted barley and 1 Tbsp of agave syrup in a cup and a half of water out on the windowsill, letting the bacteria that naturally live on the grain husk start to ferment the sugar. After a few days, there was a white scum on the top, it smelled sour, and the pH had dropped well below 4.0, which was a good sign: at this pH, bacteria like lactobacillus and pediococcus can live and produce lactic acid (the sourness present in yogurt and one way to sour a beer), but it’s too acidic for bad-tasting or more dangerous bacteria (e.g. botulism) to survive.
I then prepared the main wort:
- 3/4 lbs 2-row barley
- 1 lb malted wheat
- 0.5 lbs flaked wheat
- 0.5 lbs rolled outs
- 3 lbs wheat DME
- 2.25 lbs pilsner DME
I mashed the cracked grains for 45 minutes in 1.5 gallons of 150F water, then added 2 more gallons and the dry malts. Rather than boiling the wort and adding hops at this point as I would with a normal batch, I let it cool to about 100F, poured in the windowsill-soured starter I’d made the previous day, covered the pot and wrapped it in insulating towels, and let it sit for a day. This let the bacteria in the sour starter take over the wort, multiplying and souring the entire batch.
The next afternoon, I resumed brewing– I brought the now sweet-and-sour wort to a rolling boil, which also has the effect of killing any lactobacillus and other wild flora growing in it– this means the initial souring is as sour as the beer will get and I won’t get the more complex flavor of many sour beers, but I also don’t have to worry about other contamination multiplying after I bottle and ruining the beer over time. I boiled it for an hour as usual, adding hops and other flavoring typical of the Gose style:
- 0.5oz Santiam hops @ 60min
- 0.8oz salt @ 60min (about 0.5oz sea salt + 0.3oz lemon flake salt)
- 0.45oz coriander seeds @ 5min
After cooling with a borrowed wort chiller, I tested the OG and it was 1.057 (corrected for temperature)– exactly what I’d been shooting for. Into a second bucket it went (since my first bucket was busy fermenting a Rye Session):
I pitched in the yeast started I’d also prepared the night before (Boiled 2 pts water + ½ cup pilsner DME for 10min. Cooled the light wort covered in a cold water sink (maybe 15min) until cool, around 85F. Put in a sanitized quart jar, pitched room-temperature White Labs 029 Kolsch yeast, covered w/ sanitized foil, shook for about a minute to heavily aerate, then set on counter to sit overnight) and off we went.
It fermented vigorously over the next few days, and other than a few tastes and gravity samples I let it go for three weeks, until the yeast dropped out, the SF stabilized at 1.015 (about 5.5% ABV), and it cleared up, eventually looking like this. Mysterious.
Before bottling, I took a taste (uncarbonated): it had a lightly sour smell, a pale, malty body with a hard to pin down “funky yogurt-like” taste, not really lip-smacking tart or citric acid acidic. We’ll see if it ends up undrinkable or interesting.
For extra amusement, I decided to label it Gözer, as a shout-out to both everyone’s favorite Ghostbusters villain and the Gose style: