Meerts
Overview
Meerts, or Bière de Mars in French, is a low strength beer produced following lambic production methods. Historically this beer would have been brewed at the same time as lambic, with the wort coming from the later runnings of a lambic mash. Meerts is spontaneously fermented and was traditionally blended with lambic to make Faro. While Meerts has almost disappeared, it is still produced by Brouwerij Boon (Boon_Meerts) and incorporated into Gueuze_Tilquin_(Draught_Version), Tilquin_Faro, Quetsche_Tilquin_(Draught_Version) and Mûre_Tilquin_(Draught_Version) at Gueuzerie Tilquin.
Brewing Meerts
Historic Production
Meerts was traditionally a product from the later runnings of the mash. As the extractable sugar levels decrease with continued rinsing of the grains during the sparging process, subsequent mash runnings have progressing lower original gravities (lower levels of sugars for fermentation). The sugar-rich early runnings of the mash would be used for producing lambic, leaving the later runnings for Meerts. These two different worts would then be boiled separately.
References to a beer called "Naar goed", made from the later runnings of a lambic mash, can be found at least as far back as the 1820s[1]. By the mid 1800s, this final runnings beer is referred to as "Bière de Mars" in French-language brewing texts. Bière de Mars had an original gravity around 5 P[2], or about 1.020, and a final alcohol percentage around 2-2.5% ABV.
Modern Production
Today, Meerts is only produced by one lambic brewer: Brouwerij Boon. Low gravity beers from the later runnings of a lambic mash are no longer produced by lambic brewers. and the Boon Meerts is brewed as a stand alone beer rather than as a portion of the wort from a lambic brewday.
Consuming Meerts
Meerts was an integral part of Faro production in the mid 1800s, with Faro was described as a 50/50 blend of Lambic and Meerts. This blending was usually done after fermentation, but there is also mention of some brewers blending before fermentation[2]. Although modern Faro is almost always only produced from lambic, the Faro produced by Gueuzerie Tilquin is a 50/50 blend of lambic and Meerts. Meerts is also used to produce the draught beers at Gueuzerie Tilquin.