Wednesday, February 20, 2013

Wild Yeast Culture Experiments - Homebrew Horny Tank

In a 2007 NHC Presentation, Vinnie Cilurzo (of Russian River Brewing) suggested homebrewers try keeping a Horny Tank (inoculation tank) for maintaining mixed cultures. Used in many of the sour breweries in Belgium, he thought it may be a good way to keep a mixed culture viable without keeping a starter or brewing on a production schedule. A run-down of the process:
  1. Start a normal batch of sour beer with a mixed culture.
  2. Allow the beer to ferment in a plastic bucket for at least three months.
  3. Any time after three months, brew another batch of wort.
  4. Transfer the first batch to secondary for further conditioning, leaving behind a bit of liquid, the yeast slurry, and trub.
  5. Immediately add fresh wort to the fermentor with the wild yeast slurry.
  6. Repeat.
I started my own "Homebrew Horny Tank" last October. I brewed a blonde wort with a traditional turbid mash and inoculated the batch with several doses of revitalized, commercial bottle dregs. I plan to mature the beer in the bucket, tasting every few months.

The fear in using plastic buckets to condition a wild-fermented beer is that the bucket allows too much oxygen diffusion, resulting in excessive acetic acid production. After doing some research, it seems this fear is perpetuated by a single source. Although this article is an incredible resource for brewing sour beer, I believe the plastic bucket deserves a second chance.

To be safe, I will only disturb the beer to take samples, and I will purge the headspace with CO2 after sampling. When the beer is "ready", or if it displays the slightest amount of acetic acid, I will transfer it into a keg, leaving behind about a quart of beer, trub, and slurry. I'll then immediately transfer another batch of wort into the bucket and start the experiment over.

So far the results have been positive. Surprisingly, the bugs from the bottle dregs made quick work of the wort, completing primary fermentation in nine days and forming a pellicle in about two weeks. My first (and most recent) sample was three months after brewday (1/13). As expected, the beer tasted very young, with only a slight prickle of acidity. The aroma had a heavy sulfur note, which I believe will mellow with time (I've had sulfur aromas in a few other young sour brews). More importantly, the beer showed no signs of acetic acid production in the aroma or flavor. So far, so good.

In keeping with the theme of this blog, I want to find mixed culture methods that will translate well to a commercial scale. My mixed culture starter method could be utilized in a commercial brewery, but I believe it will often not be financially or logistically feasible. The brewery may not have the space or funds to allocate a fermentor or yeast propagation vessel specifically for wild yeast. At the same time, banking a special blend, or buying several strains of yeast and bacteria to produce a relatively small quantity of beer can also be extremely expensive.

In addition to those producing only sour and funky beers, I believe the horny tank technique could also work for commercial breweries producing them in limited amounts. Though still taking up fermentor space, it allows the brewer to consistently produce sour beer from the culture, rather than just store the slurry. The horny tank is flexible, allowing the brewery to keep a batch of fermenting sour beer and a viable culture in the same vessel. Though some may call this method sacrilege or assume its a shortcut, the time, resources, and money required to create a barrel-aged sour beer often makes them prohibitive. As homebrewers are creating fantastic funky and sour brews in glass, plastic, and stainless, I believe commercial brewers can do the same.

I will continue to make updates on this experiment as well as others in this series. To be honest - I don't see the series ending. I hope to continue playing with sour beermaking techniques, learning new techniques, finding new bugs, and creating new flavors. Let's face it - you can never have enough good sour beer around the house!

Monday, February 11, 2013

Double Oatmeal Brown

We served two homebrews at our wedding: a west coast-style IPA and an oatmeal brown ale. To my surprise, the brown was the heavy favorite among our guests.

The second iteration of this recipe is brewed to my tastes: higher in gravity with a creamier, chewier mouthfeel. I felt the original had a lot to offer in terms of malt flavor, so the ratios of Victory, pale chocolate, and debittered black malts are similar. After the first tasting, the flavor seemed somewhat hollow, with not as much chocolate as I remember in the original. I added 4 oz of cocoa nibs in the keg to give the flavor a boost.

Though it may not fit into any style guideline (or be suitable for drinking throughout a wedding reception), I enjoy a well-made, beefed-up American brown ale for many reasons. Similar to its imperialized bretheren (Imperial Red, Double IPA, etc.), a Big Brown can add some pizzazz to the BJCP category, reeling in the beer geek and beginner alike. It is a brilliant understudy to imperial stout, bringing similar levels of complexity with greater quaffability and affinity for food. It strikes a chord with anything coming off a grill, without roast or intense bitterness clashing with char or spice. As an ingredient, it adds depth to chili, French onion soup, ice cream, etc., without the roast or bitterness twang.


Brewday: 01/19/12

Estimated OG = 1.069
Estimated FG = 1.014 - 1.016
Estimated efficiency = 56.3%
Batch size = 6 gal (into fermentor)
Boil time = 60 min

14 lbs Rahr Pale Malt (61.7%)
2.5 lbs Briess Victory (11%)
2 lbs Flaked Oats (8.8%)
2 lbs Pale Chocolate (make?) (8.8%)
1.25 lbs Muntons Crystal 60L (5.3%)
1 lbs Castle Debittered Black Malt (4.4%)

Water: 6.5 gallons distilled, 4 gal drinking water (Kroger)
Adjusted water to 69 ppm Chloride with CaCl2 (per Bru'n Water) in boil


Mashed in with 7 gal at 170F
T = 156
pH ~ 4.7
Added 2.0g Baking Soda, pH ~ 5.3, T = 153F

Sacc. Rest for 1 hour – stir 30 min through boil (T = 152F at 30 min)

Vorlauf then run-off with muslin bag

To help channeling (increase efficiency): started pump, dialed in flowrate stirred up, then started vorlauf. Spread vorlauf around instead of leaving hose in one place. Slower runoff then normal.

Sparged with 3.5 gal at 165F – let sit for 15 min before vorlauf (same procedure as first runnings)
Collected 7.2 gal at 1.061 (recipe = 7.7 gal at 1.059)


Added 0.7 oz (measured – 20.4g) Apollo (18.6%) at start of boil
30 min gravity = 1.069 (15% evap)
Whirlfloc tablet added at 15 min
1 oz (28.6g) of EKG added at 10 min
Added 0.5 gal water before KO

KO – chilled to 61F

OG = 1.074


Pitched at 62F (slurry from ~3.5L 1056 starter, packet of dehydrated S-05) – pure O2 for 45 sec
OG = 1.074
01/27/13 – FG = 1.015 (7.8% ABV) – transferred to keg at ~17psi

01/30/13. Carbonation good. Great beer, slight alcohol warmth, slight espresso-roast character, missing flavor in the middle of the swallow. Added 4oz cocoa nibs soaked in vodka.

02/10/13 – Increased kegorator temp to 45F. Flavors are much more rounded and bright at this temp, and the chocolate flavor is a nice addition without being overpowering. There is still some alcohol warmth, which is where I believe the plasticy tastes comes from. If it gets worse in the next day or so, I will pull the cocoa nibs to be safe.

Also thinking about adding some raspberry puree to (at least) a portion of this beer. No bugs - I think there is too much roast character to be complementary.