Fast Souring with Lactobacillus

About three weeks ago I brewed a Brown Ale without any hops in the boil, then pitched a starter of Lactobacillus Plantarum into primary and allowed it to sour for 48 hours before adding yeast.  The idea is to have a quick-turnaround (a few weeks instead of months or even years) sour beer.

Apparently this is a thing now.  I had suspected that most of Pizza Boy's draft sours were made this way, and I tried a sour brown at Troegs' tasting room over the summer that used this technique.  It's not a new technique; this has been a popular way of brewing Berliner Weisse and Gose on both a homebrewing and commercial scale for years.  But as far as applying the technique to other grain bills (bigger, darker, less wheat, no wheat), I thought I was onto something new and have been wanting to experiment with the technique for some time.  I guess I need to read more, or pay better attention, or pick up on the obvious cues around me because I now realize that there are breweries all over the country who have been doing this for several years, and every week it seems another commercial brewery is releasing one of these quick sours.

This technique is a departure from the more traditional methods of producing mixed-fermentation "sour" beer in that the lactic acid producing bacteria (in this case Lactobacillus) are allowed access to the wort sugars prior to the introduction of the primary fermenter (Saccharomyces or Brettanomyces yeast).  When done correctly, it seems to produce a cleaner, simpler, more straight-forward sour beer than older, more traditional methods.  Beers produced this way tend to range from refreshingly tart and sessionable to puckeringly sour, although lacking the subtle, nuanced complexity of beers that are soured slowly over time by multiple souring organisms.

There are a few reasons a brewer may decide to use this technique, possibly the best among them simply that the brewer wants a light, refreshing, crushable session sour in their lineup.  Or, maybe the brewer wants to avoid the risk of contamination/ infection in their fermentation equipment--a great feature of this technique is that the wort can be soured in the kettle, then boiled (killing off the Lactobacillus), and fermented as normal with "clean" Saccharomyces.  Maybe a commercial brewer is just looking for a quick way of jumping in on the bandwagon, adding a sour beer to their portfolio without an excessive investment of time or fermenter space.  Or, in the case of a homebrewer like myself, it may seem like an easy entry into the world of sour beer making.

Let's rewind back to three weeks prior to my Brown Ale brew day.  Back to my first attempt with this technique--a Berliner Weisse.  Following the instructions on  the milk the funk dot com wiki, I made a 1.032 wort from equal parts floor malted Pilsner and wheat malts.  I did not boil the wort.  I did not add any hops.  I simply ran off into the kettle, heated and held the wort at 170 for 15 minutes to pasteurize, then knocked out at 95 degrees into carboys and pitched a starter of Omega Labs Lacto Blend (L. Plantarum and L. Brevis).  Easiest brew day I have ever had.  After two days in primary, the pH of the beer was down to 3.5, and I added a giant starter of White Labs Saccharomyces "Brett-like" Trois.  Two weeks later, the beer was down to a stable final gravity of 1.005, and after three weeks in primary, I bottled half and split the other half into carboys to dry hop (half on Amarillo, half on Galaxy).

Berliner Weisse:  That gorgeous hazy pale
hue comes mainly from the starchy character of
the wheat, preserved by this no-boil method

There are three points at which a brewer can choose to quick sour with lacto prior to primary fermentation:  the mash tun, the kettle, and the fermenter.  Mash souring is believed to be the historical means of producing Berliner Weisse and Gose.  Originally it likely occurred spontaneously, or "magically" as the wort chilled, traveling through the ideal Lacto temperature range over time.  Modern brewers can emulate this process by mashing normally, then cooling their mash to around 120, and adding either a pure lab culture of Lactobacillus, or a handful of unmilled grains, which naturally contain enough Lactobacillus cells on their husks to take hold and sour the mash.  Last year I made two Berliner Weisse batches using this technique.  After 48 hours the mash was pleasantly tart with no off aromas; I ran a two-step decoction to raise it to mashout temp, ran off into the kettle, boiled and proceeded as a normal clean primary fermentation.  It was fun and rewarding to be able to get the souring without adding any cultured micro-organisms, but now that I've done it, I don't feel the need to repeat it when there are other more straight-forward options.

Kettle souring is such a popular approach that I'm growing tired of hearing about it.  The reason for its popularity, as mentioned above, is that the brewer can boil the wort once the desired sourness is reached, then proceed with what is just another clean primary fermentation, thus mitigating the risk of infecting cold-side equipment.  The brewer simply mashes as normal, runs off into the kettle as normal, cools to 110-120 (or lower depending on Lacto strain) and pitches the Lacto.  After 24-48 hours, the wort is boiled and the process continues as normal.

Whether souring in primary, kettle, or mash tun, the key to doing it well is temperature control and oxygen control.  Most of the commercially available Lactobacillus strains have an ideal temperature range in the 100-120 Fahrenheit range.  Pitch above 120 and most if not all of your cells will die before the temp drops below 120.  Pitch at or below 100 and you won't get the cell growth you need for a good quick souring--not only missing desired Lacto fermentation character, but worse, likely picking up nasty off character since the wort pH did not drop low enough quickly enough to prevent spoilage microbes from taking hold.  The wort may develop a vomit or diaper aroma as a result.  Oxygen is also the enemy of Lactobacillus fermentation.  It is a very good practice to purge the vessel (fermenter, kettle, or headspace of mashtun) with co2 prior to adding any Lacto.  Too much oxygen exposure over enough time will allow your Lacto to produce ethyl acetate, lending a nail polish remover or varnish aroma to the wort or beer.

So, what about this Sour Brown that I brewed?  Well, in anticipation of this beer, I held back about 200mL of the Lacto Blend from the starter I had made for the Berliner.  My intention was to follow the same process with my Sour Brown as I had with the Berliner.  I would make a starter from the reserved Lacto, and I would ferment the Brown with fresh Trois harvested from the Berliner fermentation.  Unfortunately, when I opened the reserved Lacto slurry to pour it into the new starter, I was assaulted by the smell of nail polish remover.  I had failed to limit oxygen exposure, carelessly just covering the beaker with aluminum foil!  The slurry had to be dumped, and I had no pure Lacto left in the house.

In a pinch (and following a suggestion again found on milk the funk dot com), I ran out to the grocery store and picked up some Goodbelly probiotic shots.  These are 2oz liquid shots that are meant to be probiotic supplements; the probiotic in this case:  Lactobacillus Plantarum!  A characteristic that makes this strain unique is that its ideal range is 90-100 degrees, which makes if very effective in the human gut, which is also why I pitched it at 95 rather than the 100-120 earlier discussed.  I made a 1.5L starter and added the probiotic shot.  Two days later, I made the Brown Ale wort (this one, unlike the Berliner, did get a 60 minute boil) and the entire starter went in.  Two days after that, I transferred 5 gallons of my Berliner onto dry hops, pulled a healthy slurry off the fresh Lacto/ Trois cake and added it to the Brown Ale.  This weekend, I will bottle half the batch and rack the other half to a smaller carboy with Omega Labs Brett Blend.  Once the Brett takes hold, I will add Pinot Noir juice, and later down the road, Pinot Noir soaked oak cubes.  I can't wait to see how this turns out!

To Blathe:  the no-Brett, no-fruit, no-oak version.  2 gallons  were bottled after a stable final gravity was reached with Trois.
The other half of the batch was then transferred onto Brett, later to get cherries and Pinot Noir soaked oak cubes.

Now that I have a couple of sour fermentations under my belt using this technique, it seems time to get some more long-term mixed culture projects going.  I hope in the coming weeks to fill a few carboys which will go down for extended fermentation and aging over the long winter months.  First up will be 12 gallons of Golden Sour, which will get a very high mash temp, be primary fermented with a Saccharomyces strain, then inoculated with assorted bugs.  Five gallons will get Wyeast Roselaire (a blend of several strains of Brett, Lacto, and Pediococcus); the other half will be split among 1-gallon jugs and individually inoculated with dregs of various commercial beers (Jolly Pumpkin, Sante Adarius, OEC, Tilquin, and Crooked Stave probably).

Though there are multiple techniques out there, the fundamental consideration in all mixed-culture fermentation is how to give the souring bacteria and Brett access to enough wort sugars.  Saccharomyces will out-compete the other micro-organisms in an environment rich in simple sugars (which all can consume).  In a highly fermentable wort, Sacc may leave virtually nothing for the other microbes to work with.  The classic way of dealing with this was to produce a highly unfermentable wort (either with turbid mashing or high mash temps), so that there would be plenty of complex chain sugars left for the souring microbes to work with after the Saccharomyces yeast had consumed all the simple sugars.  These are not as easy for the microbes to break down, but they work long and slow at it over time.  It is this slow metabolism over time that adds great complexity to the beer, especially when Pedio is involved.

With this "more modern," fast souring method, a more highly fermentable wort can be produced (easier to consume, faster souring) because the souring microbes are given a chance prior to adding the competitively-advantaged yeast.  

There are also other methods, in between these two extremes, but no one method is really a substitute for another.  That's the beauty of different methods; they each will produce a unique result.  The brewer will best serve himself by selecting the method that will yield the result he is targeting in a given beer.  I am looking forward to trying them all.