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Notes from Jeff Sparrow, WildBrews: Beer Beyond the Influence of Brewer’s Yeast (2005)

• Lambic, the traditional beer of Brussels, is spontaneously fermented by the particular combination of microorganisms residing near the valley of the tiny Senne River and aged in wooden barrels.
• You can spontaneously ferment beer anywhere in the world. You must develop a taste for your own local lambic.
• The wort is transferred to wooden barrels where fermentation may last up to three years.
• The best lambics have some acidity, a bit like white wine, but not much more. According to Frank Boon, lambic brewers desire the character of Chardonnay.
• Lambic of less than two years old is “beer in progress” – still undergoing fermentation. Young lambic of five to six months old has a combination of the sweetness of the unfermented sugars and some bitterness from both hops and from yeast still in suspension.
• After two years, a lambic can be quite dry and taste almost like a finished product (ready to blend as a gueuze).
• Faro was once a blend of different strengths of lambic, produced with several different runnings (sparges) of the same mash and usually sweetened.
• The oldest existing beer style, traditional producers consider lambic “the mother of all beers.”
• Inoculated Lambic. A true lambic must be spontaneously fermented. A brewer pitches microorganisms dominant during lambic fermentation to effectively “mimic” the fermentation cycle to produce a beer often called a “pseudo-lambic.” The first decision regards the choice between individual commercially available cultures of Brettanomyces, Pediococcus cerevisiae, Saccharomyces cerevisiae, etc. or the use of a blend.
• The self-contained fermentative process of lambic cannot be precisely reproduced by inoculation. I do not, however, dispute the success of brewers using a “pitching schedule.”
• One schedule mirrors the microbial stages of lambic. Pitch the Saccharomyces cerevisiae immediately after cooling the wort to 68F. After the completion of primary fermentation, add Pediococcus cerevisiae. Approximately six months later, when the pH is low, add Brettanomyces. This schedule attempts to introduce the microorganisms to the wort at a time when conditions favor their growth and production of their desired by-products.
• A different schedule adds Brettanomyces immediately aftger the end of primary fermentation, prior to any lactic acid-producing bacteria. After six to eight months, add Pediococcus cerevisiae and wait. The theory behind this schedule is that you can always acidify the wort later. This may differ from the traditional cycle, but Brettanomyces grow slowly in lambic wort, and this schedule will give them a chance to reproduce without acid-producing bacteria competing for nutrients. If you are not using a turbid mash, which favors Brettanomyces growth, this schedule may be your best option.
• The final point regarding inoculated lambic. Ferment the wort in a single vessel. Do not transfer/rack the wort until you are ready to age a portion on fruit or to blend/bottle. Use of a single vessel during all stages of fermentation allows the microorganisms to metabolize nutrients present in autolyzed yeasts.