Wednesday, July 1, 2015

The summer of Gose.

I would normally use a swing top 1L growler,
to keep the o2 at bay, but it wasn't available.
There may not be a more popular trend in American craft beer right now than the revival of German Gose. Over the last few years the beer community has been focusing more and more on session strength beers and with sours rapidly growing in popularity Gose fits both trends. Gose (pronounced Goes-Ahh) shares some similarities with Berliner Weisse they are both low in alcohol and tart, but Gose is brewed with a saline water profile giving the style a very unique personality. Like Berliner Weisse, Gose is brewed with a 50:50 mix of wheat and barley, spiced with coriander and a small amount of hops in the boil then finally fermented with a blend of lactic acid and Saccharomyces. What you end up with is a slightly salty, light bodied, floral and tart beer in the 3.9%-4.9% ABV range. I don't consider myself an expert on the history of Gose but it has been a dying style over the years, making it very difficult to find classic examples. If you're looking for more background or history check out This articleThis one, or the ever growing Milk The Funk Gose Wiki for more links and information (watch that video, its great).


A few years ago I played with a technique called Sour Worting to brew some tart Berliner Weisse beers (mostly no boil versions, a bit too inconsistent for me), which from the production level, as I mentioned, is quite similar to Gose. The idea behind Sour Worting is to give Lactobacillus Bacteria a head start on creating lactic acid, a key component of the style, under conditions that favor the bacteria. The brewday using this method is quite short, about 2.5-3 hours for a 5 gallon batch in my case and with my second child on the way this fall I see a lot more of these in my future.
co2 purging the Better bottle.

I start by building a 1L starter for the Lactobacillus strain I am using, in this case L. Brevis from White Labs, incubated warm at ~100-120F in an anaerobic environment for 2-3 days. After which I take a PH reading to ensure things are progressing, so long as it's under 3.8pH I assume we are in good shape. I didn't follow these procedures on this batch but check out the Starter Media for Lactobacillus post on Eureka Brewing. I plan to implement his results going forward when build the media for a Lacto starter.

Brewday for this beer is pretty standard until we hit a boil, using a no sparge setup I mash with all my water for 60 minutes then run off to the boil kettle and hit a boil. Once the boil is achieved I add a small amount of hops, 1/2oz of Sea Salt (go light on the salt to start, you can always add more at packaging but can't take any out!) and Coriander. Let the boil roll for a couple minutes, just enough to sterilize the wort, and then cut the heat. Keep in mind that the hopping rate when working with Lactobacillus is key. High IBU concentrations can inhibit certain strains of Lactobacillus' growth and thus their ability to create lactic acid. Keeping the IBU's under 5, or even none at all, is a good guideline to follow. Any more than 5 IBUs and your chosen Lacto cultures may have a difficult time dropping the pH to the levels you desire. 

After the short boil the wort is chilled to 120F its gently transferred to a co2 purged fermentation vessel so as not to aerate the wort, as most strains of Lactobacillus perform optimally in an anaerobic environment (strain dependent, and I've read this may not be the case with Brevis).  At which point I pitch the starter of my Lacto culture, and use a heating pad to incubate at ~100F for 2-5 days, or once desired acidity (or pH) is reached. Pre-acidifying the wort with 88% Lactic Acid prior down to 4.5pH, to pitching your Lacto starter, sets you up with a more optimal environment for Lactobacillus to perform (among other reasons regarding head retention). 
Be warm my babies.

After 48 hours of incubation I pull the first sample to check gravity, pH and give it a taste. If you have an active Lactobacillus culture built up there should already be a big drop in pH and a noticeable acidity, with residual sugars remaining the acidity can be overshadowed so make sure to measure either pH or Titratable Acidity. This example was a little slow, the pH was 3.9, down from 4.5 my vial of Brevis was about 3-4 months old so that could have been the culprit. One thing I would like to mention here is that White Labs states their Brevis (a heterofermentative strain) culture can achieve 80% AA which is fine so long as it creates the acidity I want and ferments out clean. I've been experiencing full attenuation in 3 days using their culture which cuts into the creation of Lactic acid for an otherwise Lactic acid driven beer. This has prompted me to play with other strains and blends of Lactobacillus, mostly of the Homofermentative variety, for the most optimal fermentation, posts on those to follow.

In most cases I would reach my target acidity or pH, chill the fermentor down and add a strain of Saccharomyces or Brettanomyces to ferment out the rest of the beer, most folks find US-05 works well in those low pH environments. But in this case Brevis achieved 85% AA and the beer was cleanly fermented and had a decent acidity finishing at 3.65pH (I wanted a bit more though it tastes great) so there was no need to add a secondary strain. If the beer does not finish as acidic as you would like you can choose to dose the beer with some 88% Lactic acid but use a deft touch as too much can be overwhelming. Some people think it tastes synthetic, or medicinal, in high concentrations but if used lightly it can get the beer closer to where you want it.

This batch was brewed, fermented out, kegged and tapped in 14 days at a pH of 3.65. Below are tasting notes after being on tap for about 3 weeks, with the recipe details below.

Nobody Gose There Anymore, It's Too Crowded

Appearance: Hazy very pale yellow color, almost white-ish, with a wispy bright white head that fades quickly due to the acidity. Moderately high carbonation (carbed to 2.5vol). Always an odd color with these short\no boil beers.

Aroma: First wafts are pretty clean, with a bit of a grainy\earthy character and a touch of spice and lemon zest. The aroma is not huge, but you can tell it's going to be a lactic beer.
Fresh pour, haze abounds, head fades.

Taste: It starts with a slight tartness upfront immediately followed by a bit of salinity. The the wheat character takes over in the middle of the mouth lending more body than you would expect, finally finishing lightly tart with a sting on the sides of cheeks fading and finishing very dry. 

Overall: Its a very delicate tart beer with notes of lemon, grain, and a moderate salinity. The finish is dry and tart, it makes your teeth dry as you clammer for another sip a similar sensation to when drinking a fresh squeezed lemonade. At the 4% ABV range I have been crushing these after mowing the lawn mid-day on a weekend, I'm a suburban Dad now no long a city Yuppie, which makes this is acceptable practice. When I kegged the beer I was underwhelmed as I thought it needed more acidity, I still think that, but it ended up being a very balanced beer that reminds me more of the very few classic German Gose I've had. Although I was reaching for something like Westbrook Gose on the acidity scale I am very pleased with how this came out.


Brew day: 4/28/2015
Kegged: 5/12/2015

Recipe Specifications
--------------------------
Calibrating and measuring pH.
Boil Size: 6.00 gal
Post Boil Volume: 5.80 gal
Batch Size (fermenter): 5.50 gal
Bottling Volume: 5.00 gal
Estimated OG: 1.035 SG
Measured OG: 1.038 SG
Measured FG: 1.006 SG
ABV: 4.2%
Estimated Color: 3.0 SRM
Estimated IBU: 5 IBUs
Brewhouse Efficiency: 70.10 %
Boil Time: 2 Minutes

Grain:
50.0% - 3lbs 11oz - Weyermann Pilsen (1.5 SRM)
50.0% - 3lbs 11oz - CMC White Wheat (3.5 SRM)

Hops:
Boil: 2mins - 0.75oz  Strisslespalt [3.9 %] 4 IBU
Boil: 2mins -  0.50oz Sea Salt
Boil: 2mins -  0.50oz Coriander, freshly ground seeds.


Mash:
Sacch rest - 60 min @ 148 F 

Sparge:
No Sparge, full volume of water in the mash, 7.10 gallons.

Misc: 

2 comments:

  1. Great post. About to start Gose and this was quite timely.

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  2. Hey - I am curious your experience with this method and the potential for DMS. One would think that a small 5-15 min boil with pilsner malt would not be enough. Granted, Brulosophy has recently started to debunk this commonly accepted practice.

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