Berliner Weisse is an ancient German style that predates the Reinheitsgebot and an official regional exception to the law. It is basically a light bodied, low abv sour wheat beer. Berliner Weisse was almost extinct a few years ago, with just one or two breweries in or around Berlin still brewing the style, only for very local consumption. Recently, however, the style has experienced a reboot as American craft breweries took an interest in it, and there are now several commercial examples on the market.
There are several techniques that a modern homebrewer can use to achieve sourness in a Berliner Weisse, but authentically the sourness should come from a Lactobacillus Delbruckii (lacto) bacterial fermentation.
My attempt employs a sour mash. I chose this technique for two reasons: 1. It is likely the most historically accurate technique, and 2. According to people who know more than I do, this technique should yield a more complex and nuanced flavor profile than other techniques.
Other techniques would include anything from simply adding lactic acid into a clean fermented beer before bottling, to adding a commercial lacto culture in primary with or without a clean ale yeast (saccharomyces cervacae) or wild ale yeast (brettanomyces), to souring the wort with lacto in the boil kettle for 12-72 hours before boiling.
I chose a full sour mash. After mashing my grist (60% German pilsner malt, 40% wheat malt) at 149f for 90 minutes, I allowed the temperature of the mash to drop to 110 (top of the optimal temperature range for lacto growth). Once it hit 110, I added a few cups of uncrushed 2-row malt. Dormant Lactobacillus naturally exists on the outer surface of all brewers malt, and it will become active, reproduce, ferment, etc if given the right environment. A 104-111f gruel of sugary goodness just happens to be the right environment. However, all of the lacto present in our grist was likely killed off in the 149 degree mash, so it was necessary for me to add fresh grain into the mash once it cooled to 110. A few cups into this 5 gallon batch should be enough to get this party started.
Currently, I am 24 hours into the souring phase of this project, and things appear to be going well. The mash is sitting at 100f, with a pronounced funky sour aroma. I can't claim the smell is exactly pleasant, but it's also not really unpleasant in any way. The grist has dropped ten degrees in 24 hours, so if it continues to drop at that rate, tomorrow around 8pm will be as good a time as any to complete the runoff, sparge, and boil the sour wort.
Below, I'll detail the steps of the process so far, and I will continue to add to this post as the process moves forward.
The First 24 Hours
The Mash
I picked up a cheap five gallon cooler and converted it into a crude mash tun. I replaced the spigot with an old 1/4" stainless steel spigot I had lying around. I then inserted a five gallon paint strainer bag into the cooler, wrapping the opening of the bag around the rim of the cooler and securing with a large rubber band. Like I said, crude. But this should work just fine as a false bottom for the time being. If this works well, I will probably dedicate this piece of equipment to sour mashes.
 |
| Mashing in. pilsner malt, wheat malt, some acid malt and a handful of rice hulls in about 2 gallons of water to settle at 149. |
 |
| Resting at 149 for 90 minutes. |
The Pitch
 |
| An unmeasured amount of fresh 2 row (let's call it a bunch) waiting to be stirred into a 110f mash. |
 |
| Almost there. |
The Souring
 |
| Blankets keep my kids warm; why wouldn't a blanket help keep this cooler warm? Here's where it will rest for the next 48ish hours. |
 |
| The lacto laden grains have been stirred into the mash. I wrapped the entire cooler in plastic, partly hoping to hold in heat, mostly in the superstitious hope of preventing the lid from blowing off as fermentation picks up |
 |
| 24 hours in, the mash has a distinct funky sour aroma. |
48 Hour Sour
Tuesday, April 22. Currently my Berliner is in the fermenter, happily bubbling away with a nice healthy pitch of Cal Ale yeast in the low 60's. Things seem to be going smoothly, and I am excited at the prospect that I will soon have a nice, light, clean Berliner Weisse.
Yesterday I arrived home from work around 8pm, perfect timing to move this beer along to the next step in its evolution. I removed the cooler lid to find the mash holding at 90f with a pleasantly sour aroma. In 48 hours time, it had only dropped 20 degrees. That's great news.
On advice from another member on HBT, I conducted a double decoction to raise the mash temp up to 170 for a proper mash out. This temperature rise accomplished two things: it stopped the lacto fermentation, and more importantly, it reduced the viscosity of the sugary wort for a more efficient runoff.
 |
| Bringing the first decoction to a boil. |
After the second infusion, the entire mash was up to 170, which meant it was time to begin running the sweet wort off the grist. There were several "firsts" for me during this mash.
- This was my first sour mash. Seems to have gone well, still holding at 90 after 48 hours. Nice bready sauerkraut aroma with no off smells (vomit, baby diaper, roadkill, etc) that would be indicators of undesirable bacteria other than lacto. I learned that lacto actually likes temps up to 122 as the top of its range, so next time I will pitch my unmilled grains and begin the souring rest at this temp. I could probably get another 24 hours out of the souring rest, yielding a much more puckering tartness in the finished beer.
- This was my first decoction mash. Necessity pushed me to attempt a technique I had admired from afar for quite some time. Turns out it's not nearly as difficult or cumbersome as I'd imagined, and now that the intimidation factor is out of the way, I will probably use a decoction mash in the near future for a nice complex, malty German lager with a drying finish (I'm lookin' at you, Helles Bock).
- Finally, this was also my first batch sparge. Not a big deal, but it was my first. I had the ability to fly sparge, but it would have meant getting out extra equipment at 10:30 at night. It also would have meant sparging with the lid off and massive heat loss. Why bother with that when it was just as easy to do a two step batch sparge and end up with the same volume and gravity of wort into the kettle...
 |
| The cloudy, sweet/ sour wort slowly fills the kettle. |
Not everything went as planned last night, however. Just as I sat my 5.5 gallons of sour wort on the Blichmann floor burner to boil, I ran out of propane. Checked the other tank: empty. Ugh. To the stovetop I went, with my 15 gallon kettle. Luckily it was only a five gallon batch, even luckier it was only a 15 minute boil. The stove struggled just a bit, even though I covered the kettle with foil while ramping up the boil. Once boiling, foil removed, I never did achieve the strong rolling boil I get with the Blichmann, but it was definitely boiling and I did get a measurable boil off, even in that short 15 minutes.
Ran it through my plate chiller and managed to knock out about 5 gallons into the fermenter at 64 degrees. Perfect. Pitched some Cal Ale slurry and moved it into my fermentation chamber for the next phase of its life.
Bottling Day
Wednesday, May 7. Looks like my Berliner Weisse has finished at around 1.010. That's a bit high for the style, but the ale yeast is definitely finished. It's been in primary for fifteen days, and the hydrometer reading has not moved in over a week. With that knowledge, and confident that there's no live lacto left in the beer since boiling, I went ahead and bottled.
I managed to get twenty 500ml and thirteen standard 12oz bottles out of the batch. Couldn't be more psyched about this beer. Taste of the bottling sample was phenomenal! Not sure why it only dropped to 1.010, but I'm not sweating it at all. Plenty of unknowns with this batch. I didn't take any pre-fermentation gravity readings, have no idea what my mash efficiency was or what my abv is.None of that is important. The most important--the only truly important--thing about this batch is that I had a successful lacto sour mash which yielded a freaking delicious sour ale that will not last long.
I will need to do this again very soon.
There will be no more edits to this post. The next time this beer will be featured on this blog will be in an inevitable write-up on the finished beer in a few weeks.
Prost!
