bioreactor Archives - The Pour Report

Bioreactor A2 – Sour red with a subtle toasty background.

The somewhat laborious process of maintaining mixed cultures via what I’ve called, for lack of a better name, my Bioreactor Project is beginning to bear fruit (or in this case, sour beer). The recipe and review below represents the second generation fermentation of mixed culture “A” grown up from the following beers:

Cantillon Gueuze
Tilquin Gueuze
Russian River Beatification
Crooked Stave Surette
Jolly Pumpkin La Roja

I’ve managed to consistently maintain the bioreactor on a 4-month refresh cycle. The results so far have been positive, although I’ve noticed that the fermentations have rather sluggish starts, which is a bit concerning. If I were to implement this program on a commercial level, I would decrease the refresh cycle to something more reasonable, perhaps refreshing every couple months. Unfortunately, the practicality for doing this at a homebrew level is somewhat limited (at least for myself).

For this iteration of the recipe, I wanted to see how the souring culture might synergize (or clash) with a slightly toasty malt background. Vienna malt plays a prominent role in the beer bringing a subtle toasty note to what should be a fairly funky sour beer.

Specifications:
Size: 1.25 gal
Efficiency: 66%
Attenuation: 85%

Original Gravity: 1.054
Terminal Gravity: 1.014
Color: 11.13 SRM
Alcohol: 5.25% ABV
Bitterness: 0 IBU
Terminal pH: 2.60

Malt Bill:
2.75 lb (91.7%) Weyermann Vienna Malt
0.25 lb (8.3%) Weyermann Carared

Mash Profile:
160°F – 60m

Water Treatment:
Extremely Soft NYC Water
Added to mash: 2g Calcium Chloride

Hopping:
0.25 oz Aged Cascade Hops (0.0% AA) – 90m

Kettle Additions:
0.25 ea Whirlfloc Tablets (Irish moss) – added during boil, boiled 15m
0.25 tsp Wyeast Nutrient – added during boil, boiled 10m

Yeast:
Bio Reactor “Culture A” – racked from a 4-month old fermentation using the same culture

Tasting Notes:

Judged as a BJCP 28B Mixed Fermentation Sour Beer

Aroma (8/12):
Prominent pie cherry, fruity Brett aromatics on the nose with a punchy level of lactic sourness. There is a nice soft, bready malt nose featuring light toast along with some oxidized dark fruit (think prune). Some of the more funky Brett aromatics of wet hay and earth are subtle, offering background complexity. As the beer warms, the beer exudes a nutty, almost Amaretto-like aroma.

Appearance (0/3):
The beer strikes a deep copper tone with light chill haze. A vigorous pour offers up a very slight white foam that quickly dissipates. The beer is a bit under-carbonated, making head formation a difficult task. Also not helping matters is lactobacillus’ ability to degrade foam positive proteins.

Flavor (12/20):
The beer strikes a medium acidity, primarily lactic in nature although a touch of acetic acid is perceptible. The first sip reveals a prominent THP flavor that is reminiscent of Cheerios, which is actually quite pleasant when tasted in concert with the lightly toasty Vienna malt base. There is a low level of residual sweetness which helps take the edge off of some of the stronger acetic acid notes. Interestingly, when tasted at 4-months old, the beer had a fairly robust plastic-like phenol which seems to have been transformed at this point into other more positive flavors.

Mouthfeel (1/5):
The beer has a medium to medium-light body with a very low carbonation level. The beer is in desperate need of something to lift it off the palate; a task that the acidity only marginally accomplishes.

Overall Impression (6/10):
The beer falls a bit flat, but does offer up some interesting complexity, particularly in the commingling of some of the THP and toasty Vienna malt characters. The touch of oxidized malt flavor plays nicely with the Brett fruitiness—something that I think could become even more interesting if actual fruit (think tart pie cherries) were introduced into the mix.

Good (27/50)

Previously I've been keeping my house sour culture refreshed with frequent feedings of starter wort.

I have typically been keeping my house sour culture refreshed with frequent feedings of starter wort.

Over the past couple of years, I’ve cultured and grown up bottle dregs from a variety of commercial sour beers to complete several different projects. These dregs are a great way to add biodiversity to the commercial blends (like Roeselare) that I typically start a sour beer with and tend to produce a more interesting final product. As I acquired these cultures, I began combining them with the intent of developing a variety of house-mixed cultures of bacteria and yeast that I can maintain and use to completely ferment out sour beers. The intent is to continue shaping these mixed cultures until they get to the point where they can consistently produce quality sour beer in a predictable time frame. I fully expect the blend of microbes within the culture to drift, but hope an eventual homeostasis will take hold within the culture. Currently, I have built three different mixed cultures around a spectrum of cultured microbes harvested from commercial beers.

One of the biggest tasks in maintaining a culture like this is the frequent feedings required to keep a culture viable. The idea of maintaining my cultures through periodic feedings of fresh wort that would eventually provide the steady byproduct of sour beer seemed like a great idea. And so, the idea of a sour culture bio-reactor was born. The idea is pretty basic. I’ve put together a schedule of brew days that in theory will consistently provide nutrition for the culture as well as produce a steady stream of sour beer for evaluation. Every four months I brew a different 3-gallon batch of moderate gravity wort that gets split three ways to feed one gallon of fresh wort to each of my three mixed cultures. On brew day I transfer the previous batches of now fermented beer off the culture to a clean glass aging vessel where it will continue to develop for another 8 months (1-year total fermentation time) before packaging. The cultures are then transferred to the freshly brewed wort for a new round of fermentation. After the initial one-year cycle, the bioreactor will consistently output three, 1-gallon batches of sour beer every four months. The beauty of running three cultures in parallel with the same wort is that I’ll be able to compare side-by-side the impact each different culture has on the finished product. My hope is to experiment with different grain bills to better understand the interrelationship between grain bills, mash temperatures, and mixed culture fermentation.

I initially started this project using a single mixed culture. To date, this culture has been through 3 generations of wort. I’ve tasted the first two generations (currently 4-months and 8-months old) and the results have been pretty outstanding; and consistent within the limited sample thus far. I’m optimistic that with some luck and diligence I’ll be able to shape these cultures to the point that they produce sour beer that is both delicious and unique to my brewery.

The first round in the bioreactor ready for fermentation. The initial recipe was 90% Pilsner, 10% Carapils, and had a starting gravity of 1.054.

Tag Archives: bioreactor

Bioreactor Culture A – Gen 2

Tasting Notes:

Developing House Sour Cultures – A Bioreactor Approach