Many people wonder why anyone would intentionally sour a perfectly good beer. Well, if you have ever tasted a Rodenbach Grand Cru or one of the many fine Lambics in the world, you'd know why. The reason hops are added to beer is to offset the sweetness of the malt with the bitterness of the hops. In other words, to balance the taste. Souring the beer can achieve a different kind of balance; a sweet and sour balance. There are several different methods for souring a beer. You can sour the entire mash until the desired sourness is achieved, then boil the mash to kill all the souring organisms. You can sour some of the mash, boil it, and combine this with the remaining fermented wort. Finally, you can add the both the souring bacteria and yeast to the wort at pitching time and let the beer proceed through a normal fermentation.
In the past month I have attempted two of these procedures. Paul Harwig and I created a Berliner Weiss using the sour the entire mash procedure and I created a Belgian Red Ale using the "pitch it all at once" procedure. I'll attempt to describe both of these procedures, but the jury is still out on how the beers will turn out.
For a 10 gallon batch of Berliner Weiss, only 10 pounds of grain were needed (5 lb. of wheat and 5 lb. of 2-row malt) since we're shooting for an OG of 1.030. After a single-infusion mash at 151 degrees and sparging to collect 11.5 gallons, the mash was cooled to approximately 100 degrees and inoculated with freeze-dried lactobacillus capsules. The entire mash was kept insulated for 24-48 hours until the desired sourness was achieved. The wort was then boiled normally with 1 oz. Hallertauer (IBUs: 5) added at the beginning. Chilled normally and pitched with a one pint starter of Berliner Weiss ale yeast. Hopefully, this beer should turn out very sour and tart. Paul is getting some sweetening syrups from his sister in Germany so we can experience the real thing.
The other method I've experimented with is the combined culture being pitched together. After mashing and boiling the grains for a Belgian Red Ale (in the style of Rodenbach) I pitched both the Belgian Red Ale yeast and a wild yeast/lacto culture. This will ferment for about 6 months to a year to give the strange beasts a chance to do their thing. If I can get anywhere close to a Rodenbach I'll be extremely happy. It's one of the most enjoyable beer experiences I've ever had. All of these strange cultures were obtained from a company in Georgia called Headstart Brewing Cultures in Athens, Georgia. The owner, Dr. Brian Nummer, recently wrote an article for Brewing Techniques magazine on the same subject. He can be contacted at (706) 548-7051.
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