Bernard Dewulf
Jan Adriaensens, production manager at Brouwerij Westmalle (Photo courtesy Brouwerij Westmalle)

In the forthcoming issue of All About Beer Magazine, I discuss Brouwerij Westmalle’s Tripel, one of the most important beers in the Belgian canon, in my Classic Beer column. Until that beer came along in the 1930s, amber and brown beers were the overwhelming norm in Belgian brewing. (There was another early blond, Witkap Pater, developed by the same brewer who formulated Westmalle’s, that came out a year or two earlier—though it was Westmalle’s that ultimately influenced imitators.) Indeed—fun fact—Belgium’s most famous blond ale, Duvel, was until 1970 an amber ale. I corresponded with Production Manager Jan Adriaensens for the column, and he conveyed more than I could include in one article.


Hops are not the most important flavor element in Westmalle, but they are pronounced—unusual for a Belgian beer. This is partly because Belgian beers—including Westmalle’s—highlight yeast character, but also because the high attenuation levels leave very little body to balance bitterness. Adriaensens seemed to allude to that when he began his comments this way: “Yes we have ‘hoppy’ beers, which is not the same as bitter beers.” (his emphasis). But Westmalle Tripel is pretty bitter. Even Americans will nod their head appreciatively. I wanted to know what the brewery was shooting for there. As with so many classic originals, Westmalle was never copied—all subsequent versions were a good deal more sweet and lacked that layer of herbal hop flavor.

“Of course, the bitterness is also very important, which is around 38 to 40 EBU for Tripel,” he agreed. (EBU is a different bitterness measure, but is very close to IBU.) “Our hop recipe contains about six different hops, which are dosed as hop cones in our boiling vessel.” I wondered whether he used a consistent blend of hops or, since hops vary year to year, whether he used different varieties. “As we also have a very fruity beer, the hop balance is very important and not easy to achieve. The right balance between fruitiness, bitterness, and hoppy flavors needs a constant ‘follow up.’”


Belgian beer is characterized by yeast, first and foremost. It may be spicy or fruity or even funky, but it is almost never neutral. Brewers can coax their yeasts to produce these flavors in a number of ways, from the mash through to bottle-conditioning. Historically, the fermenter itself contributed a lot to the way the yeast behaved. Beers exposed to open fermentation produce more esters, as do beers in shallow fermenters. Pressure inhibits yeast expression, and tall cylindro-conical fermenters create pressure by stacking up that liquid weight in a narrow column. Beginning 20 years ago, Westmalle first broached the idea of moving from its square (closed) fermenters to cylindro-conical tanks (CCT). I wondered how that process went and reported some of Adriaensens’ response in my column. Here is his fuller answer.

“We knew already from literature that it is important to start with the right dimensions of the cylindro-conical tank,” he began. “The hydrostatical height of the beer in the fermenter should be as low as possible to prevent saturation of carbon dioxide in the beer, as this inhibits the formation of the fruity esters, which are very important for the fruitiness of our beers.

“As a change cannot be done without being 100 percent sure of the quality and the flavor of our beers, we placed one pilot CCT with a lot of possibilities for sampling and measuring different parameters like the evolution of the Plato, yeast concentration, and the flavor of the beer.

“With this pilot installation we have done fermenting and yeast-harvesting tests for eight years. [At the end], a triangle tasting of the beers coming from the traditional horizontal fermenters and the cylindro-conical fermenters gave no difference. We discovered the exact parameters of time, pressure, temperature, volumes, and many more parameters, to have the guarantee of a fruitiness Tripel/Dubbel, as we used to have the traditional way.”

As I mentioned in the article, taking eight years to conduct an experiment is, for Trappist monks, not an especially long trial. I love going to the Cathedral in Brussels, because the long-sighted vision of the church is evident in the architecture. Built over 300 years, the building reflects different architectural trends over the period as you walk around it. Compared to this length of time, eight years is nothing—especially when the thing you’re working on may be around tens or hundreds of years more.

I’ll leave you with one final, charming quote. Westmalle shares its yeast strain with the monks at Westvleteren. As he was discussing this, Adriaensens wrote, “in another brewery, this would do the yeast no harm, as long as he is not harvested there and reused” (bold mine). This answers one final question—the gender of yeast, in Belgium at least, is masculine. Now we know.

While you wait for my column on Westmalle to arrive, go find a bottle or two and sample. It’s a wonderful, historic ale.

Jeff Alworth is the author of the book, The Beer Bible (Workman, 2015). Follow him on Twitter or find him at his blog, Beervana.