IN PRINT: Sour Plum Beer

Posted by on June 26, 2011 at 1:00 am.

Home Brewed Sour Plum Beer

This month my article on home brewing a sour plum beer is featured GRID, check out the article online or read below:

A lambic is a wild fermented beer from Belgium that is marked by a bright, funky, and intense sour flavor with a wonderfully clean finish. It is perfect for escaping a bit of the hot humid weather during a Philadelphia summer, and is the inspiration for Sour Ales made in the United States today. Think of it like a grown up lemonade, or the sourdough version of beer. The process for making a lambic is long and complicated, sometimes taking 3 years to produce a single complete batch. It starts in the fall where the wort is left out in enormous trays (coolships) with open windows allowing ambient yeast to settle and spontaneously ferment the brew. It ends after it has been barrel aged for anywhere from 1-3 years often blended (young and old) to create a gueuze. It can also be refermented with fruit (a kriek has whole cherries, a framboise has raspberries), or blended with fruit juice just before bottling to create a lambic almost like a desert wine. There are more than 86 possible microorganisms in a lambic, ranging from yeast in the air, to yeast in the brewery, to yeast in the barrels themselves. The process leads to a beer that has wildly different properties based on the year and place it was made, with endless flavor profiles and a deeply devoted following in the United States.

The most talked about yeast in the production of lambics, gueuzes, and sour beers, is Brettanomyces. It is the maker and destroyer of beers, and depending on what you are trying to make you either love it with a severe intensity or hate it just as passionately. It is naturally occurring on the skin of fruits, and is virtually uncontrollable once it gets going. It can contaminate anything porous, especially non-glass brewing equipment like wood or plastic, and is impossible to eliminate without replacing your equipment. This one yeast is largely responsible for the all of the sour beers created in the United States, and Brettanomyces along with various strains of Lactobacillus are the foundation for creating the flavor of a lambic.


Even modeled on the lambic tradition, brewing a sour fruit beer is simple enough. The Roeselare Ale yeast already has a beautifully balanced blend of Brettanomyces and Lactobacillus strains, and the fruit only needs to be thawed and added for the secondary fermentation. The most important aspects of brewing a sour beer are patience, isolation, and sterilization, and none of these are too hard to achieve. You need patience because the entire process takes about 6 months, isolation and sterilization to stop contamination in beers you make afterwards. Designate tubing and a plastic fermenter for sour beers, let it age in a different room, and you’re good.



  • 5 lbs Gambrinus Munich Malt
  • 5 lbs Gambrinus Pilsner Malt
  • 2 lbs Weyermann Carahell Malt
  • 2 oz Aged German Hops (2005)
  • Wyeast 3763-PC Roeselare Ale Blend
  • 9 lbs of plums, frozen and thawed (for second rack)


  • mash the grain between 150F-155F for about 2 hours
  • sparge to collect 6-7 gallons of malted water so that after the boil you have 5 gallons of liquid
  • add the aged hops and bring it to a boil for 1 hour
  • let cool using your preferred method (bathtub of cool water, wort cooler, etc)
  • transfer to a carboy, pitch the yeast and allow to ferment for 3 weeks
  • rack onto the plums in a plastic fermenter (bucket) for 3 months
  • check periodically for plums that might float to the top and mold, remove them as needed.
  • bottle age for at least 6 weeks, continues to age for at least 3 years.



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