I admit it, I’ve been a sour beer holdout.  It’s not that I’m sour adverse, but in my 15 years of brewing and 20+ of drinking craft beers, I’m still excited by “just malt, hops, and yeast”. However, recently we were asked to produce a fruited sour in our pilot brewery, and with very little experience in this style we decided to take an iterative approach to this challenge by making a neutral beer with moderate alcohol content, controlling sourness in the kettle, and adding fruit syrups at time of consumption (similar to Berliner Weiss). 

Here are our steps:

  1. Control the Bacteria:  Selected one strain of Lactobacillus (delbrueckii) and grew a 1-gallon starter culture on 10 Plato wort (pH adjusted to 4.5 with lactic acid to inhibit growth of unwanted bacteria).  We assessed the flavor and pH regularly over the next few days to determine our preferred target of pH 3.4.
Strain of Lactobacillus (delbrueckii)
  1. Produce a Flavor Neutral Wort:  We chose to use a grist makeup similar to Berliner Weiss since it is known to play nice with acidity. We used a 50%/50% blend of Synergy Select Pilsen Malt and White Wheat Malt to produce a 9.5 Plato wort that we boiled and then cooled to 90°F.
  2. Inoculate the Wort:  We added our 1-gallon Lacto culture to our cooled kettle and monitored the pH as it dropped from 5.3 to 3.4 over 20 hours. 
Flavor Neutral Wort
  1. Hops and Yeast:  We added Magnum hops (targeting 8 IBU) and boiled for 60 minutes prior to cooling, oxygenation, and pitching German Ale Yeast.
  2. Finishing:  Secondary fermentation for two weeks followed by forced carbonation to 2.7, 3.0, and 3.3 volumes; we decided that 3.0 was right for our taste. 
Having a taste of the finished product
  1. Drink and Determine Preferences:  Experiment with addition of various syrups and flavors at differing carbonation levels and make observations.


Throughout this process I gained an appreciation for how clean a sour beer could taste with controlled lactic fermentation and clean ale yeast, there was no funk and a super clean finish allowing the malt to show through…likely too clean for drinkers who want a little funk.  We found that the lingering tartness was easily balanced with syrup sweetness and fruit aromas.  Our favorite additions to this beer were raspberry, woodruff, and peach syrups, but we also tried coconut, watermelon, cherry, pineapple, and strawberry.  In the future, I will be interested in including additional bacteria and yeast strains (Brettanomyces, etc) in fermentation and experimenting with a wider range of flavors and infusions.

Woodruff and Raspberry Syrup Flavor and Color Additions

For a 1 bbl batch of the sour beer, we would use 21 pounds of both Synergy Pilsen Malt and Malted White Wheat, plus 22 grams of Magnum hops during a 60-minute boil.

Original gravity – 1.038

Finished Gravity – 1.009

SRM – 3

Approx. ABV – 3.7%

IBUs – 8