Becoming a beer sommelier – Part 2

The adventure continues! In a previous blog, Becoming a beer sommelier Part 1, I wrote about what I learned in level 1 of the beer sommelier course last year. In March I started level 2 in Amsterdam. So far every class has been a fascinating in-depth journey into the wonderful world of beer, like off-flavors, the magic of yeast, and beer and food pairing. This week’s class was a special one though! We brewed our own beer! What a great opportunity to get an inside look at how it’s done in a professional brewery. Here is a short account of our brewing experience yesterday at Brouwerij Klein Duimpje in Hillegom.

It all begins with a recipe

Our assignment was to brew a Dortmunder beer. Weeks before we had already decided on the recipe that we wanted to make on brew day. Though it’s a classic Germany pale lager – meaning there are certain criteria to adhere to, like bottom fermenting – there are still plenty of options to play with. The choice of malt was relatively simple: Pilsner, Munich and tiny bit of Melanoidin. Deciding on the hops was a different story. We had quite some discussion there (no idea why, because Saaz is quite common in a Dortmunder, personal preference?). All I know is, Saaz was out of the question! Hallertau and Tettnanger made the cut. Both are mild and herbal hops. For the bottom fermenting yeast someone in my class was able to get ‘live’ lager yeast from another brewery by taking it from a tank that had finished fermenting (much like in photo 8) and putting it into a sterilized jerry can (photo 7). Yeast plays a big role in creating the flavor of the beer, so choosing the right strain is crucial.

The mash

The first part of brewing is actually milling the malt, but this had already been done for us the day before. Crushing the malt into grist is necessary in order to be able to extract the starches during the mash, which is done – you guessed it! – in a mash tun. This is the part where the grist is steeped into hot water (not boiling) to convert starches into fermentable sugars. I got stuck in traffic, so I missed pouring the grist into the mash tun! (Thanks guys for taking pictures!) This part takes a little more than an hour. There’s a lot of waiting around when brewing. In between we did other things, like a brewery tour and beer tasting! 

1. The recipe
Brewing computer
2. Brewing computer dashboard
Lautering tun
3. The lautering tun

The boil

After mashing you end up with lovely sugary wort, which is ready to be boiled. The spent grain is first filtered out in a lautering tun and can be used as animal feed or to make bread or cookies. But if the starches have already been converted into sugar for the yeast to feast on, what’s the point of boiling the liquid? This is important for several reasons. First, it sterilizes the wort by killing off unwanted micro-organisms and boils off unpleasant aroma compounds. It also extracts bitterness from the hops that are added during the boil, a process called isomerization. The boil lasted at least an hour, during which the dried hops (pellets) were added. Because the tanks are so big, they have little mobile ladders so you can reach the lid and (useful for curious people like me) take a look inside the tank! Of course a lot of the process is automated, so no need to keep looking at your watch how far along the boil is; the computer (photo 2) will tell you! Brewing is way more fun with cool gadgets!

4. Peeking inside the lautering tun
5. Spent grain
Adding hops to the boil
6. Adding hops to the boil


After boiling all solids are removed in a whirlpool and the wort is cooled to a temperature at which yeast will thrive and get the fermentation process going. All the steps leading up to now are actually just prep for the yeast to do its job! The beer goes from the whirlpool via the cooling system into the fermentation tank, where we added the live yeast from the jerry can (photo 7). Here it will sit for several weeks. On a sign outside the tank the brewer keeps track of what batch it is and how the gravity evolves during fermentation. Our beer is currently fermenting in tank #1!

We also tested a fermented beer straight from the tank! After removing the yeast (photo 8, fairly easy in this case as bottom fermenting yeast sinks to the bottom of the tank) and measuring the carbon dioxide level with another cool gadget (photo 9), we got to have a taste of their newly brewed Weizen. It was still quite ‘young’ and not finished yet, but definitely already had a lot of carbonation and that recognizable banana aroma.

Such a great experience and a fun day! Many thanks to Klein Duimpje for having us!


The Brewery

Erik Bouman, the brewery’s founder, began brewing beers in 1994. Soon after he started winning prizes and in 1997 won the Dutch amateur beer award for best winter beer (with the beer Erik de Noorman). For many years Klein Duimpje was a gypsy brewery, using the facilities of Scheldebrouwerij to brew their beers. Finally in 2011 they found a location in Hillegom to set up to their own installation and in 2012 they opened a brewery and taproom. The current brewing capacity is 200 hl. The taproom is open on Friday, Saturday and Sunday.

Every year the brewery organizes a Midsummer beer festival where they invite brewers from Zuid-Holland. This year it will take place on Saturday July 7 from 1 pm – 9 pm. Tickets (20 EUR) are no longer available online, but can still be bought at the door!

Live yeast
7. Our 'live' yeast
Removing yeast from the tank
8. Removing yeast from the tank
Measuring the carbondioxide in beer
9. Measuring the carbon dioxide
Marking the fermentation tank
10. Our beer!
Klein Duimpje Brouwerij
11. Touring the brewery
Drinking beer from the tank
12. Drinking beer straight from the fermentation tank
Dort Ohne Saaz
13. Our own beer label!
14. Klein Duimpje's most popular beer De Blauwe Tram

All photos by Tina Rogers.

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