The Art of Souring Wort
Starting any business is an uphill challenge. But Off Color chose an even more difficult path by introducing one of the major beer spoilers into the building, almost immediately. The brewery started with two dudes standing in a mostly empty warehouse next to a couple used stainless steel farm boy tanks with industrial heating pads ratchet strapped around them getting ready to pitch their first culture of the brewery. But it wasn’t our good friend Saccharomyces cerevisiae, the name used for brewers yeast if you want to sound smart, or pretentious, or both. Instead, we started with a Lactobacillus delbrueckii pitch, a major beer spoiler that homogeneously produces lactic acid, an acid with a relatively mild sourness also present in such foods as sauerkraut and yogurt.
Generating Lactic Acid
Lacto (which is short hand for lactobacillus and not to be confused with lactose — the milk sugar featured in certain types of stout and trendy IPA styles) has some specific preferences to optimize it’s lactic acid production.
- First, lacto likes it warm. We keep ours at 40 dC (or, for you American readers, 105 dF) with those aforementioned industrial size heating pads ratchet strapped around our single wall stainless steel tanks.
- Lacto is not a huge fan of hops, unlike most users on beer rating apps. When boiled in wort, hops provide iso alpha acids to beer wort. In addition to bitterness, this compound also acts as a preservative. A big reason hops originally found popularity in beer brewing over everything else that grows in the ground is because it retards the growth of certain beer spoiling bacteria such as lacto, which would be super helpful if you had to brew into a clay pot using water from a stream like a thousand years ago.
- Lacto is very happy chugging away at simpler sugars (glucose and fructose) than saccharomyces who does better with maltose. So we feed our lacto generator a meager wort of about 5% sugars by weight the lacto acidifies to an average pH of about 3.0.
Insert ‘Gose’ Pun Here
The lactic acid produced in our lacto tanks was first used in a beer slapped with a Troublesome Leipzig style Gose label. Gose was a beer style no one really heard of until around 2013 when the style gained some prominence in the US. The “business of brewing” teacher from brewing school told us it was a stupid idea to lead with a gose as one of our flagships. But we didn’t listen, or we forgot. Either way, we dumped our first pitch of lacto into the glucosey, unhopped wort contained within our heated tanks. Since then, neither of the lacto tanks have been completely emptied, but instead we pull out of them when we need sour wort or a lacto culture and refill with fresh wort.
Keep it Consistent Stupid
It almost seems all-mighty god creationismed the natural selecting of microfloral in our lacto tanks for our zymurgical amusement. The interesting changes the flavor profile of our sour wort underwent during the first six months made creating a consistent final beer very difficult. A task in which we largely failed. Early 2013 Troublesome was a very different beer from late 2013 Troublesome. Almost all the variation came from the solera-like process of pulling sour wort out of the lacto tanks and then refilling with fresh wort for each batch of gose we put out. Our sour wort stabilized during the start of 2014. The conditions in the tanks (always kept at 40 dC, never oxygenated or hopped) fostered a lacto strain that threw a veggie soup type of acidity. This specific mutation seemed to endure for many years and consistency went way up.
Propagation; tank steaming
The secondary function the lacto tanks serve is to propagate lactobacillus for other projects. Fierce Berliner Weiss was first to use our house lacto with a batch souring technique in the brewhouse kettle where we cooled down the wort inside the kettle, blanketed the kettle with carbon dioxide, and transferred some sour wort out of lacto tanks into the kettle and allowed the wort to acidify overnight. The kettle souring process worked briefly, but the toll on the lacto tanks as we increased production of Fierce while still consistently brewing Troublesome proved to be too much for the lacto tanks. While this was a time before we had the capability of doing cell counts, the number of lacto cells in those tanks certainly hit an all time low. By the end of the first summer of Fierce, neither Troublesome nor Fierce were hitting flavor spec for acidity and the brewers were saddened as we decimated our lacto cultures which just started getting normalized. But months later, the lacto cells regenerated and our beloved acidity returned.
After that summer we purchased a slightly better lacto holding tank (although the welds are also terrible) to batch sour our Berliner Weiss beers and give us the production flexibility to make all the batch soured variants including Spots Tiki Weiss, Yuzu Fierce Berliner Weiss, and Wari chicha de molle (Wari’s a whole ‘nother post). A separate batch souring tank helped us keep our cultures purer during batch souring, as we steam the tank to purge all the oxygen and keep airborne microbes out (especially problemsome aerobes which can turn you beer really nasty). This process aided batch souring as our lacto culture spread instead of thinned.
An Intervention with a Little Help From Theodor Geisel
For a few years after these process tweaks, the lacto produced nice, clean, tart wort. Until it didn’t. The degradation was gradual and it took a while to notice but the tang in Troublesome greatly faded and it was time for intervention. So we sat down with all googol lactobacillus cells and told them we loved them and were concerned for them but felt change was necessary. So in late 2017, we introduced a supplementary strain of Lactobacillus brevis to one of the two tanks. This lacto strain is a stronger acid producer, more hop acid resistant and featured a flavor profile different from the original Lactobacillus delbrueckii culture. We now get a rounder, fuller but still very clean acidity from that tank which we named Thing 2, while the un-supplemented 2013 culture in Thing 1 is used for all our batch soured Berliner Weiss beers and other acidified variants.
Like why we named our tanks
Thing 2 and Thing 1?
If you were going to ask, don’t bother.
But if you really need to know,
go ask your father.
Our batch sour beers with lacto from Thing 1 tend to stay on the lighter side while showcasing the veggie, zippy tartness paired with fruit esters from a free temperature rise, farmhouse-style fermentation. The lacto cultures in Thing 2 are just now being featured in newer brands. This new breed of lacto acidified wort needed more malt to round out the flavor of the acidity it produces. With a new lacto flavor profile to integrate, we conceived ideas for two new brands: Staveyard Oud Bruin and Silly People American Style Gose.
Symbiotic Aging
Maybe I shouldn’t say Staveyard Oud Bruin started with a plan, because it didn’t. Really just the timing worked out in late 2017 when we had freshly emptied third use Willet barrels and our Le Woof Biere de Garde at the end of conditioning holding in stainless fermenters.* Coincidentally, this was like the same month we pitched Lactobacillus brevis into Thing 2. All that was left to do was to wait, And, I guess, think of the idea to blend the two together.
At some point during the next 50 weeks, we tasted through all the wood barrels collecting spider webs in the back of our brewery. We decided the biere de garde was in a good spot for blending as it was taking on an aged, mildly sweet oxidative character, not unlike honey, playing off the maltiness and subtle pepper phenols of the base biere de garde. A longer stay in wood was not going to do this beer any favors.
Also at some point during this 50 week period, we started observing the changes in the lactic acidified wort coming out of Thing 2 by exclaiming things like: “Troublesome is really good!” The acidity was fuller and slight more intense but still very clean. As we had been showcasing the sour wort coming out of Thing 1, we thought it’d be nice to showcase the other side of our lactic acid production.** The plan quickly became to build an amber young beer boiled with a bunch of wood staves to extract an extra layer of tannins to compliment the largely oakless aged biere de garde sitting in those fourth use barrels.
It was hard to remember the last time I drank an Oud Bruin, or Flanders brown. As this project progressed, we realized our blend was going to essentially be just that with the exception of unconventionally using the young beer to provide the acidity rather than the aged component. So prior to blending, I picked up a La Folie from New Belgium. It was transcendent and set an upsettingly high bar. The feeling of inadequacy lasted until I tasted our final blend. Staveyard came out just as we hoped with multiple balancing layers of complexity integrating rounded acidity, malty sweetness, honey oxidation, and wood tannins with light mahogany hues.
Silly American (Gose)
2013 was an interesting time to release a gose beer as the style was generally unheard of and unadulterated by the whims of American craft brewers. We chose to make a more authentic German style variation, which balances acidity, salinity, and wheat character is complimentary ways. Troublesome gose was also designed to serve as a base for different blends, such as Sparkles Finds Trouble Hibiscus Gose and One Percent Whiskey Barrel Aged Wit with Cherries. But craft beer makers took the subtleties of the style and cranked them up to the point where some comically claimed craft beer was dead. But that’s what American craft brewers do, they accentuate beer flavors to the point of hyperbole. See: American brewers rolling out goses featuring overly salty and sour components or highlighting a wild list of ingredients and microflora. But hey, we are certainly not above designing “silly” beers.
Where Troublesome is fermented with traditional brewers yeast and back blended with pasteurized, batch soured wort, Silly People American Style Gose is batch soured in the fermenter with our Thing 2 (Lactobacillus delbrueckii and Lactobacillus brevis blend) to develop a stronger acid profile, then undergoes a secondary fermentation with our favorite oddball wine yeast (Torulaspora delbrueckii) to develop a fruit cocktail ester profile, and lastly undergoes a mixed Brettanomyces and Saccharomyces fermentation to complete fermentation. The triple fermentation adds a complex and fairly potent flavor profile balanced by a chewy grain bill including flaked wheat, flaked oats, and flaked barley. We then supplemented the mouthfeel by adding French grey sea salt with the citrus notes coming from green coriander as well as lemon zest. Although all the flavor components are elevated, the overall balance didn’t suffer so you can have more than a sampler.
Why did we just give away all our ‘secrets’?
Fermentation offers endless possibilities for flavor contribution in beer and we find it much more interesting than adding an extreme amount of hops or other crazy, over-the-top ingredients. Focusing on real innovation, thinking about what beer can be, and pushing craft beer forward in meaningful ways will be more impactful for the American craft beer industry. Otherwise, we may all spend the rest of our lives drinking fizzy spiked water.
*Intensive analysis of current production levels along with evaluation of capacity of oak vessel capacity sprouted an idea. “Let’s put that stuff in those things.”
**Unfortunately, this meant conceiving an idea for a new beer. But fortunately, we like conceiving ideas for new beers.
