JULY 22, 2000: Asheville, NC-- Traditional lambic brewing is alive and well in the Zenne River valley in Belgium! I recently had the pleasure of visiting the Frank Boon Brewery in Lembeek, Belgium. It was a relief to find out that small-scale brewing methods still have a good home. All of the hops used in Boon's beers are aged on-site for approximately 3 years. This aging process oxidizes the hops' acids. After oxidation, the alpha acids are no longer able to provide bittering. The preservative powers of the hops are not reduced during aging. Thus, beers can be produced that contain very little hop bitterness, while retaining their preservative qualities.

Approximately 30 percent of the grain bill is unmalted wheat. This unusual ingredient is a result of the large availability of wheat grown in the area, plus the relative difficulty of malting wheat. Unmalted wheat contributes some of the bitterness and astringency found in lambic beers. The mash tun is made of cast iron and is not covered during the mashing process. The bottom of the tun is equipped with mechanical rakes. These prevent the wheat mash from becoming "stuck" and subsequently preventing sparging. This unit has been serving breweries since before 1900, and it continues to show that mash tuns do not need to be covered.

The brewing process begins by adding water to the mash tun and then adding the grain. This mixtures is allowed to remain at a low temperature rest for a period of time, then liquid is withdrawn. This liquid is called the "turbid mash". The "turbid mash" is boiled for approximately 2 minutes. Boiling water is added to the main mash and a saccharification rest is undertaken for approximately 30 minutes. The main mash is sparged, and collected in the kettle. The liquid from the "turbid mash" is returned to the mash tun and a second saccharification rest is undertaken. The second mash is sparged, and also added to the kettle. The combined wort is then boiled for approximately 5 hours.

The mash tun Click to Enlarge

The cool ship Click to Enlarge

Following boiling, the wort passes through a hop-back and into a cool ship. The cool ship is a large flat open basin. Fans blow cool outside air across the hot wort, and the beer is cooled. This also allows the unique microbes of the Zenne River valley to enter the beer. The use of the cool ship prevents Boon from brewing from May to September, due to the high air temperatures.

The cooled wort then enters a gyle tank. This tank is subsequently used to fill the wooden casks. The casks used in the Boon brewery were made in Germany in 1880 and sent to Belgium in 1920 as reparations for the First World War.

Tasting notes on a cask Click to Enlarge

Primary fermentation occurs in these casks. Microbes present in the wood's pores, in addition to the microbes added during cooling, provide the starter culture for fermentation. The casks are also porous to oxygen, and the beer acquires an oxidized character from being fermented in these vessels. The beer is allowed to age in the casks for up to three years. During this time, it is periodically tasted and symbols are chalked on the casks to describe the flavor found within.

Following aging, the individual casks are blended to produce the desired flavors. The blended beers are then bottled. A secondary fermentation is allowed to occur in the bottle. This fermentation lasts for approximately 3 weeks. The bottles are then stored in a cold room for approximately 3 months, and then delivered to lambic lovers everywhere. A number of the brewery's practices fly in the face of standard homebrew wisdom. It just proves that great beer can be made using almost any process.

Fermentation casks Click to Enlarge

It was a thrill to be able to tour this brewery. Seeing items that I had only read about was one of the most satisfying beer experiences that I ever had. If you ever find yourself on the other side of the Atlantic Ocean, do not miss this brewery!

I almost forgot, there really are spider webs all over the place.

Brouwerij Frank Boon NV
Fonteinstraat 65
1502 Lembeek
Phone 02 356 6644

References Michael Jackson, "Michael Jackson's Beer Companion" (Philadelphia, PA: Running Press, 1993) 33-34 Jean- Xavier Guinard, "Lambic" (Boulder, CO: Brewers Publications, 1990) 55-58 Tim Webb, "The Good Beer Guide to Belgium and Holland" (Pownal, VT: Storey Books, 1999) 59

Other Articles from our Belgium Series:

The Chimay Brewery
by Al Clayson and Brian Smyth

Our tour group had the pleasure of making a pilgrimage by bus to the Chimay Brewery near the Ardennes forest of southern Belgium. Chimay is the world’s most recognized Trappist beer.