One Gallon Spontaneous Sour Beer Batch 6 and The Board of Lambicky Mysteries

Here comes another small batch of lambic inspired spontaneous beer in my long, long running effort to turn my home into a lambic/gueuze homebrewery. In my last installment I looked at reducing the volume of aged hops while trying to chase down my unusual problem of not getting anything in the way of sourness in my prior five renditions under the theory that perhaps the wort simply had too much antibacterial power. I'll talk a little about where that beer is right now, about a year old, and then get into one change to this recipe and a piece of equipment that will test a second theory. Well that seems like enough teasing the content so let's talk brewing sour beer and my questionable brewing theories.

Where is that lambic-inspired spontaneous batch 5?

Spontaneous batch 5 was my least hopped batch in an effort to make the wort ever more susceptible to lactic acid bacteria and get some sourness in these beers. Previously I had hopped these beers at the same rate as Cantillon, who knows a thing or two about lambic brewing. For batch 5 I slid down to a paltry 0.40 oz./gal. ratio after seeing so many other homebrewers kicking out spontaneous beers around this volume with sufficient sourness. 


This beer is a year old and like its predecessors it is nowhere in the sour beer territory. I didn't ph test it but just by taste it lines up with a clean saison. Slightly dry but no sourness. It has a nice honey flavor that will make a nice blending component but it is missing sourness and has only a hint of funkiness. Obviously still not getting the job done. A systemic problem across multiple batches and two different environments means more than just chalking this up to the randomness of spontaneous beer. (Sure, it could still be randomness but every batch makes the probability of a random result less likely.) 

Untested factors in souring these spontaneous beers

At least three factors remain unchanged throughout these batches which may be culprits. First, the batch size itself may play a role. Since the first batch I've had concerns whether this small volume would work, whether it was an issue with insufficient surface volume or the wort cooling too quickly. I cannot rule this issue out but I've had smaller experiments reach sourness much quicker without any problem and I'm cooling these one gallon batches as fast as other people seem to cool their five gallon batches. I also tried a five gallon batch some time ago as my first spontaneous experiment which turned out pretty close to its smaller companion experiments. Although unable to rule it out, I have enough data that this may not be an issue that it isn't on the forefront of addressing the issue.

Second, the boil time may be a factor. In each of these experiments I have opted to boil for only an hour rather than the traditional three or four hour boil. The primary reason long boils exist for lambic is because it usually takes a lot of liquid to conduct a turbid mash. This isn't so much a problem on a small homebrewing scale where manual labor seems sufficient to get out the starches and sugars from the mash tun. But maybe there is a secondary issue going on. Is the long boil degrading the antimicrobial compounds in the aged hops? I would expect a short boil to result in less extraction than a longer boil and thus less defense against lactic acid bacteria but maybe with aged hops I need to degrade them in a longer boil. Of all the other homebrew experiments I've seen replicating lambic, they all seem to do the longer boil. 

Third, perhaps the environment is a factor. Many commercial and virtually all home brewing of spontaneous beers seem to involve unloading the coolship into the open air. None of the Belgian lambic brewers do this and only a handful of commercial breweries here have placed their coolship indoors. I've long wondered whether these open air experiments are missing the point (although they seem to have no problem souring their wort). It is well known in brewing science that yeast and bacteria, especially those most desirable in lambic, are found concentrated within breweries far more than non-brewery locations. This makes sense that an environment full of sugar would harbor sugar-loving microbes who in turn become experts in chomping those malt sugars. If you've read any lambic materials from years past you know the old saw about splashing lambic around the coolship to innoculate a cooling space but Cantillon straight up sprayed all the walls of their new brewery. They clearly think this is an issue. 

Perhaps these are overlapping issues. The boil time may leave behind too many antimicrobial elements while the small batch size and open environment makes it less likely hop tolerant lactic acid bacteria meet the cooling wort surface. Maybe even adjusting the boil time but keeping the batch size means I need to do more than hope for the best that the aspen trees in my back yard can shake out the "right" yeast and bacteria. 

Changing the boil time and every drop of liquid

An easy change to make to test at least one of these theories is to expand out to a three hour boil. Adding boil time is simple but with a recipe designed for a one hour boil I need to account for more evaporation and hence completely change the water volumes for the entire recipe (and the water chemistry of brewing salts, too). I built the original recipe on the turbid mash profile in Wild Brews (one of the 2000s Brewers Publication gems) which is supposed to be based on Cantillon's turbid mash schedule. (The opportunistically named Levi Funk's early work putting together Funk Factory suggested the same.) The relatively minor work retooling the water volumes is offset by making the turbid mash brewday a little easier by having to employ less manual labor to press out those milky first few runnings. 

The complicated part of building a turbid mash schedule is accounting for the volumes flowing back and forth between the three vessels, especially with the early extractions from the mash. If you've ever attempted this turbid mash schedule you know aside from the endurance of performing a multiple hour mash, the toughest part is getting out that first milky extraction. The less liquid in the mash the more you have to press the mash to extract the liquid from the grain. With a shorter boil there was less liquid overall which in turn meant squeezing out the first runnings was a real nightmare. With added liquid it should be a little easier but still not as easy as turning the ball valve and letting them flow. 

The complicated part of building a turbid mash schedule for a small volume of beer is that the temperatures don't quite work the same. The Wild Brews/Cantillon turbid mash schedule advises that all of the infusions should be at boiling but this doesn't quite work as well on small volumes. Adding boiling water infusions makes sense for a larger volume as the thermal mass ebbs and flows across the turbid mash's yo-yo infusion and extraction schedule. By the time the runnings have been extracted the mash bed needs a lot of heat to make the jump to the next rest. On a smaller scale, especially this small, it's been my experience that the boiling water pushes the temperatures higher than the intended rests. My shorter boil schedule employed the boiling water but for this adjustment I forced beersmith to accept negative water infusions and tried to schedule the infusion temperatures to account for the intended rest temperatures as it would with a regular infusion step mash. As a result the infusions don't require a boil which will help avoid water loss due to as much evaporation. 

Let's talk about the board of lambicky mysteries

Where do the yeast and bacteria in spontaneous beer come from?

Naturally (pun intended) we all agree the coolship process is an important part of inoculating wort with the desired mixtures of microorganisms--but where do they come from? Romantic impressions of lambic and other spontaneous brewing suggests cool breezes bring a magical balance of yeast and bacteria to our wort. That's what drove the long standing myth that these beers can only arise from the Senne valley. Research suggests differently that the brewery itself selects for malt sugar-consuming yeast and bacteria, especially for brett which is not especially common in nature. You have to know that is basically true unless you have never seen a pro brewery cleaning or even cleaned your homebrewing equipment. When Cantillon acquired new brewing space one of the first things they did was spray down the walls with lambic so the space would obtain the residents from the other location. If you don't think the brewery is an important source of yeast and bacteria for spontaneous beer then I'll leave it to you to argue that point with Jean Van Roy.

At home I don't have the same luxury to hose down the walls with lambic. While I could I suppose could do that with part of my garage I don't brew quite enough spontaneous wort to reliably build up a hearty group of residents. Nevertheless, I do believe that a consistent environment of malt sugar-consuming bacteria and yeast is a critical part of consistently developing these beers with desirable brett character. I believe it is especially true for these smaller batches where the surface area is less than a larger batch and the wort cools a little too quickly outside to let time make up for the minimal surface area. 

So since I can't turn my home into a lambic-sprayed brewery I thought I could create a mobile version of the same concept. Instead of fixed walls and a coolship room I could create a mobile "wall" where a malt-consuming culture could form and then descend into cooling wort. By creating a portable brewery environment I can bring it to the kitchen on brew days to get splashed with mash runnings to feed its occupants with malt sugar. It can go outside to let native microorganisms descend onto those malt sugars. When it's time to coolship wort it replicates the coolship room, allowing the mobile environment to shake out its occupants into the wort to make friends with microorganisms drifting in the wind. 

This is not a fancy solution at all. 

I turned an inexpensive cutting board into my mobile "brewery environment" for this purpose. The cutting board is physically equivalent to the wood on walls, ceilings and rafters in these lambic breweries but without the benefit of being a lambic brewery. While cooling the wort I will partially cover the kettle with the board so the wort gets a combination of residents from the air and the wood.

Turning the cutting board into my mobile spontaneous brewery was easy work. I sanded off the stain partially out of concern for dripping chemicals into the cooling wort and partially to facilitate microorganisms taking residence in the wood. I then drilled holes in the wood. I'm not sure this is necessary but I want steam to escape through the wood so I have additional options to control surface area and temperature decline. 

I then began feeding the board with malt sugar. On the first brewday to follow I sparged additional volume to gain some low gravity runnings. I painted this onto the wood several times and then left it outside to gain occupants. I went back out and painted more runnings on the wort every couple hours for the rest of the afternoon until the board was dry and sticky. Since then I've brought it into the kitchen on brew days and let it get messy with wort drippings from equipment. When that brewday's wort went on the boil the board would go outside to the same area of my backyard where I cool wort. I'll continue to adopt this process for at least several more brewdays. Between these splashy brewdays and cooling spontaneous beer with it I expect to see a consistent culture develop on the board. I expect I will probably have to continue to feed the board with wort to keep the culture alive and consistent. 

Anybody intrigued to replicate this experiment should be aware that this is creating a board full of microorganisms which very likely include pathogens. When handling the board I am careful to wash my hands and any kitchen surfaces the board touches. I also store the board in a dry environment away from the kitchen to avoid contaminating food or kitchen surfaces. 

Well, now with this board hopefully ready to shake out malt-consuming organisms let's try a brew day.

One Gallon Spontaneous Sour Beer Batch 6 Recipe & Brewday

Batch Size: 1 gallon       
Est. ABV: 5.3%       
Est. IBU ???       
Est. OG: 1.052       
Est. FG: ???       
Est. SRM: 3.4       
Expected Efficiency: 72%       
Grain BillPounds Ounces SRM Pct. Grist
Pilsner malt1 4 2 60.00%
Unmalted red wheat  12 2 40.00%
Water Profileppm      
Bru'n Water Yellow Bitter       
PH: 5.4       
Water Additions    Mash Sparge
Gypsum    1.1g .3g
Epsom Salt    1g .3g
Canning Salt    .1g  
Baking Soda       
Calcium Chloride    .8g .2g
Pickling Lime       
Lactic Acid    .9ml  
Mash ScheduleStep Temp.   Step Time  
Single Infusion Batch Sparge       
Mash volume: 2.8 gal       
Sparge volume: 0.75 gal       
Infuse 2qt at 120F113   15  
Infuse 2qt at 150F126   15  
Remove 1qt, add to kettle, heat to 190F       
Infuse 3qt at 185F149   30  
Remove 3 qt, add to kettle       
Infusion 3 qt at 185F162   30  
Remove 3 qt, add to kettle, increase kettle heat       
Infuse kettle contents to mash tun172   20  
Sparge 0.75 gal180      
Boil ScheduleVolume Unit Time IBU
180 minute boil       
Aged hops0.25 oz 60 0
Fermentation Schedule# Days Temp.    
Yeast: Spontaneous       
Pitch at 70F365 70    
Bottle with 4oz table sugar to 3 vol100 70   

Brewday & Fermentation Notes

Brewed 2.7.21.

Here comes the obligatory first runnings photo. Oat milk has become a thing--why not lambic milk?

The added liquor for a three hour boil makes this turbid mash a breeze compared to the prior batches on a one hour boil. On previous batches I had to press out the early runnings with a mesh filter but for this mash I could run off from the ball valve on my mash tun with no problem at all. 

Four year old hop pellets

The brewday went by easily without any challenge. A three hour boil is...a long boil. When I planned to brew today I saw the temperatures were going to hit a high of 55F which would be great but by the time I finished the long boil temperatures had plummeted to the low teens. I put the cooling wort close to the house where it should be a little warmer from radiant heat from the brick wall and less exposure to the blistering wind. The board of lambicky mysteries should also help slow cooling despite the low temperatures. Well let's see what happens.

As you can see, over three hours at a frigid 13F the wort still only cooled to 72F. On my previous batches each cooled to this temperature in about two hours with none of the batches cooling in ambient temperatures this cold. Obviously the board trapped steam which maintained heat above the wort which explains the delayed cooling. 

When I removed the board the portion covering the wort had a thick layer of moisture that was almost wort like. I wonder if the dried wort I've been painting on the board was melting and dripping back into the kettle. The following day that portion of the board seemed lighter and cleaner. 

The wort remained calm for a few days but by day four krausen slowly started to appear. After a couple weeks of a very normal beer krausen the beer descended into an unmoving slumber. From here I'll wait and see how it performs. 
Source: homebrewingfun

One Gallon Spontaneous Sour Beer Batch 6 and The Board of Lambicky Mysteries