Sour Bread, Sour Beer


It ain’t right.  Intentionally pitching lactobacillus into 20 litres of homebrew doesn’t feel right to me having spent 99.9% of my time brewing fermenting with straight S. Cerevesea (brewing yeast).  It did excite me in a way that perhaps brewing hasn’t done for a long time.

Bullion Kettle Sour on the ol' kegerator.

I started homebrewing about seven years ago and have brewed more-or-less regularly since then.  Starting a new hobby is always an exciting time.  Once I got over that initial, “What the hell am I doing?” stage, and got a little more comfortable with the logistics of pots and buckets filled with liquid it was certainly something I found myself smitten with. 

It was the waiting.  It was the not knowing.  I can still remember the apprehension with which I waited for those first batches to ferment and condition.  I watched in awe as the airlock bubbled and burped away – the yeast inside chewing through sugar and spitting out carbon dioxide as if by magic.  This was evidence that I had done something, anything correctly.  Tasting was forbidden, though.  Any unnecessary meddling, sampling, or probing could infect the batch, so I had to learn a bit of patience, a bit of delayed gratification.  It was that waiting that I fell in love with.

Every decision (or mistake) made on brew day can alter a batch ever so slightly (or massively), but you won’t know the impact for several weeks until it’s ready to drink.  Premature tasting almost always leads to disappointment.  It’s for this reason that in my first year of homebrewing, I started to brew prolifically.  I began to brew almost weekly, so that I would always have something new to taste.  I brewed so much, in fact, that even six years after I left my parents’ home my dad still cracks open the occasional vintage homebrew.

My three-tier brewing setup.  Notice the high-quality craftsmanship on the mash-tun.

I quickly found that the biggest factors are always yeast health and fermentation temperature.  There is an old saying that, “Brewers make wort, yeast makes beer,” which I am happy to repeat for every ill-fated brewery tour that finds themselves with me as their guide.  The saying may be trite, but the sentiment is true enough – happy yeast makes good beer.  As I progressed in the industry and learned more about keeping yeast happy it became increasingly simple.  If I do X at Y temperature, I will result in Z.  In this way perhaps homebrewing lost a lot of the luster that it had for me in those early days.

Enter the sour beer.

Beer.  Souring.  Note the plaid blankie.  This is integral to bacteria comfiness.

I had brewed just one sour previously.  It was a Flanders Red which conditioned in my parents’ basement for over two years with decent results.  Sour beers either use brewing yeast in a limited way or eschew it altogether in favour of bacteria that creates a myriad of flavours ranging from funky to fruity to barnyard to, my personal favourite, horse-blanket.  This method of brewing breaks with the traditional X yields Y, but the drawback is that slower-working bacteria often takes years to fully develop its flavours and can infect brewing equipment which may easily cause ALL of your beers to spontaneously sour. 

The kettle sour circumvents both of these drawbacks by adding bacteria to the brew kettle, elevating the temperature to encourage bacteria to work at a faster rate, then boiling to sterilize before involving the rest of the brewing equipment.  It gets the sourness associated with classic sour beers, but lacks much of the complexity built through years of conditioning.  It’s in this way that this method has been termed a “Mickey Mouse sour” by some. 

Bacteria dying by boil.  Nothing to see here.

Two examples of this style inspired me to have a go myself.  The first was from the Belgian Brouwerij t’Verzet (http://brouwerijtverzet.be/).  We first had this beer at the Bruges beer institution, the aptly named Beer t’Bruges.  The beer was Dr. Rudi (after the hop variety of the same name).  Perhaps it was the many many rounds beforehand, perhaps it was the company, but after piling into the sleepy backstreet boozer (as close to a locals bar as one can get in the tourist-ridden Bruges), confidently ordering the beer with the handwritten tap labeled only with “Dr. Rudi” in sharpie, everyone else following suit assuming I knew what I was doing, and finding it a bitter, citrus, sour delight I was hooked.  We had countless rounds of the stuff before moving on.  As it turns out a place literally called “Bruges Beer” doesn’t really do wine, and the choice between red, white, or port declared on the menu was a bit too coarse for one in our group.  Reluctantly we left the good doctor and moved on.

Since then we have followed Brouwerij t’Verzet closely, and they seem to be rocketing to popularity within the Belgian brewing scene.  We have since collected bottles of the stuff on every subsequent trip to Belgium.  Somehow, unfortunately, it never quite lives up to that first experience, but things rarely do.

The next example that got me excited enough to have a go at it myself was Atom’s dry hopped kettle sour.  This one we had at Manchester’s Grub.  We were with the same cohort, and, bar one who made the mistake of ordering first, everyone followed suit when I chose the kettle sour.  We were all reminded of those first memories of Rudi and made sure to have a few rounds as it shared the same characteristic balance of bitter, sour, fruit, citrus, and salt. 

Local Bullion hops in the boil (and for dry-hopping).

Atom (http://www.atombeers.com) is a brewery that also hadn’t been on my radar, but certainly will be going forward.  This was another example of a tart, citrus golden ale that was just utterly drinkable. 

So, without further ado, the recipe:
#
Malt
Weight (Kg)
1
Pilsner
4
2
Acidulated Malt
0.1
3
Wheat
0.2

Calculated
OG
1.048
FG
1.011
ABV
4.93%
IBU
27.7
SRM
8.8
Efficiency
75

#
Hops
Weight
Time
Alphas
1
Bullion
15
60
7.5
2
Bullion
20
10
7.5
3
Bullion
30
0
7.5

The process begins as a normal brew day.  I treat my liquor with a bit of AMS (to drop the hardness) and metabisulphate (to remove chlorine) based roughly on the local water profile.  I mashed all the malt in one go, which may not have been the best approach as the acidulated malt can shift the pH out of the optimum range for saccharification.  I did notice the wort had a bit of a thin, starchy haze characteristic that I don’t commonly get on a standard wort, but this didn’t seem to cause any issues other than a bit lower efficiency than I would normally have seen. 

I ran off and sparged into the copper as normal, followed by a 5 to 10-minute boil to sterilize.  I had planned to then let it naturally cool to 40C, but quickly realized this would take far too long, so I got out the heat exchanger and chilled quite quickly down to a nice temp for the lactobacillus to work at.  While doing this I rehydrated the dried lacto culture according to standard yeast rehydration procedure.  I then incrementally added dried lactic acid to adjust the pH down to 4.3 and purged the top of the kettle with CO2.  The pH adjustment and CO2 help to inhibit other forms of bacteria which may produce off-flavours.    I then pitched my re-hydrated lacto, covered with a nice blankie, and left my cozy lacto to do its work for three days.  I turned the thermostat to 40C while I was at home to keep things at a nice consistent temperature.

After the wort had soured to a pH of 3.5, I proceeded to boil, chill, and ferment with S05 as standard.  I then added a bit of Bullion dry hop, kegged, and carbed to end up with another crackin’ example of a dry-hopped kettle sour.  It’s certainly a technique I will carry on using in the future.