Brewing Sahti in Pertunmaa

Brewing Sahti in Pertunmaa

Brewing sahti is traditionally learned by following and assisting a master. That’s why I visited sahti master Eila Tuominen in August 2018, in a small countryside municipality of Pertunmaa in Finland. This story documents the craft of brewing sahti so carefully that you can learn by following the master too.

Sahti master Eila Tuominen in her brewhouse
Eila Tuominen in her brewhouse, pushing the kettle capacity to its limits.

The Brewery

Like many countryside sahti brewers, Eila brews in an old cowshed. In the early 1990s, most Finnish farms had at least a few cows, but today milk is produced only at larger farms, and the Finnish countryside is scattered with small unused cowsheds. This is how Eila started brewing sahti seriously: the farm was deemed too small to keep cows, and Eila had to figure out another source of income. Two weeks after the cows had left the farm, she fired-up kettle for sahti.

Now Eila brews each year few thousand liters sahti wort for sale. When customers buy unfermented wort and ferment it themselves at home, the ale is not subject to alcohol tax. In this land of extremely high alcohol taxes, sahti wort sold very well in the 1980s and 1990s, but the demand is much lower today. Nevertheless, Eila has a loyal customer base in nearby districts. In December 2018 I drove to Joutsa to buy wort from her, and luckily I had made a pre-order because she sold every available drop of wort in fifteen minutes. During the high season, before Christmas and Midsummer, she brews as much as she can. Although Eila is a commercial brewer, she brews in the most traditional manner.

A cowshed turned into a sahti brewhouse.
Eila’s cowshed turned into a sahti brewery. The brewhouse is in a tiny “kitchen” room in the right corner of the brick wall.

Traditional Finnish cowsheds had a small room called cattle kitchen (karjakeittiö in Finnish) for heating water, cleaning dairy equipment, and storing milk before it was picked. As you’ll see, these tiny rooms are perfect for brewing Nordic farmhouse ale.

Eila’s brewhouse consists of two small rooms. The first room is fitted with a wood-fired kettle and kuurna (lauter tun) built from plywood and timber. The other room has an old milk tank for keeping wort at 4°C.

The Fellowship of Sahti

Before going into the brewing details, let me introduce some additional information. The brew day documented below was part of an eight-day tour in Finland with a group that I call The Fellowship of Sahti: beer writers, brewers and beer geeks eager to learn about sahti traditions.

Canadian beer writer Martin Thibault has documented the tour vividly in his site Les Coureurs des Boires (in French). Norwegian beer writer Lars Marius Garshol (see Larsblog) also collected lots of material, and as soon as he publishes something I will link it here.  My article on sahti in Zymurgy Magazine (March/April 2019 issue) includes recipe of renowned sahti master Olavi Viheroja, also recorded during the tour.

You can learn more about northern European farmhouse ales from stories Sahti and Related Ancient Farmhouse Ales and Sahti Recipe and Farmhouse Brewing Tips.  For a definitive and properly edited work on Nordic farmhouse brewing traditions, please check my forthcoming book Viking Age Brew.

Eila Tuominen and the fellowship of sahti: Timo Alanen, Martin Thibault, Ilkka Miettinen, Lars Marius Garshol and Amund Polden Arnesen
Eila and the fellowship of sahti (minus me taking the photo). From left to right: Timo Alanen, Martin Thibault, Eila Tuominen, Ilkka Miettinen, Lars Marius Garshol and Amund Polden Arnesen.

The Recipe

Ingredients for 123 liters:

41.7 kg Viking Sahti Malt
9 kg unmalted rye (flakes from a local mill)
One branch of juniper (see photo below)
120 g Suomen Hiiva’s fresh compressed baker’s yeast

The unusual precision of the recipe volume comes from Eila’s mastery: That is the absolute maximum she can brew with her 150 L kettle. Actually, she doesn’t measure the malts so precisely: she brews three batches from five 25 kg Sahti Malt sacks, and that makes 41.7 kg per batch. Like a true sahti brewer, Eila does not measure gravities, but this is what we measured with Lars Marius from the brewed wort and sahti served to us:

Original gravity: 1.100
Final gravity:  1.038
Calculating from these figures, Eila’s sahti has around 8 % ABV.

On the eve of the brew day, Eila prepared juniper infusion from branch shown in the photo below: she brought around 100 liters of water to a boil, added the branch, and left it to infuse until the next morning.

juniper branch for brewing sahti
This juniper branch flavored the brew.

The Early Brew Day

Eila started brewing at 6 o’clock in the morning. First, she checked the juniper infusion that was still warm in the kettle. This 100 liters of liquor was to be used for mashing and had to be adjusted for proper mash-in temperature. Eila doesn’t use a thermometer for brewing and instead tested the temperature by drawing a circle into the water with her forefinger: water should feel so hot that you can barely touch it.

Once the temperature felt right, she mixed in malts and unmalted rye, closed the kettle with a lid, and insulated the top with emptied malt sacks. Then the mash was left to rest. Actually, I and the whole fellowship of sahti were still sleeping at this time. The day before we had rented a nice nearby summer cottage by the lake from Eila, and all that sauna, sahti, swimming and grilling had taken its toll.

The earliest of us arrived at 8 o’clock to see the next steps. Eila opened the kettle, and I measured the mash temperature of 49°C. She started the wood-fire underneath the kettle and mixed the mash until 9 o’clock. Then she let the flame die, and I measured the mash temperature of 53°C. Eila was surprised to hear that the reading was so low, but perhaps the thick kettle walls were still releasing some heat. She closed the kettle with a lid and insulates the kettle top with malt sacks.

It was mash rest again. We went back to the cottage for a morning swim and breakfast.

Properly Cooked Sahti

When we came back to the brewhouse at 11:30, Eila re-lighted wood-fire underneath the kettle and began to stir the mash continuously. Around 12 o’clock the mash started to look signs of simmering.

Now, a few words about boiling the mash is in order. Some sahti brewers boil their mash while leaving the wort unboiled. Apparently, this practice stems from the age-old technique of heating the mash with hot stones. Then, some brewers speak about boiling the mash, but they actually stop when grain solids begin to rise to the surface. This may look like a gentle boil, but I have seen it already happening at mash temperatures of 80–90 °C ––  another reminder that experiencing the farmhouse brew day is superior to just hearing brewer’s story.

In our sahti tour we had already seen two brew days were the recipe included “mash boil”, but the temperature remained below 90°C. This was our last brew day of the tour,  and Lars Marius, who had especially anticipated to see sahti mash boil, was getting worried.

I had promised the group to see the mash boil during the tour, and there I was, monitoring how high the mash will go. When the mash started to look very hot, I measured 91°C in the center, and 98°C close to the kettle edges where the mash clearly bubbling. Fortunately, it soon became obvious that I don’t need a thermometer to judge the intensity of mashing.

Eila added more wood to the fire, and the mash began to boil violently. The mash rose up to the rim and she had to stir briskly to avoid boil-overs (see my video on YouTube). Occasionally the mash splashed and dripped down the sides of the kettle.

She continued the boil for around half an hour until the mash fell down to the level where it was before the boil, almost 10 cm. The foam disappeared and the mash got darker. For Eila, this remarkable change marked that the mash has been properly cooked (she used a Finnish word kypsennetty) and that heat can be shut down. In fact, Eila gives “properly cooked guarantee” for her wort.

At 12:45 Eila closed the lid of the kettle while the mash was still simmering. The mash was left to rest.

Sahti mash before and after boil
On the left the mash begins to boil and on the right it is “properly cooked”.

This is not the first time I hear someone asserting that sahti should be properly cooked. Usually, brewers mentioning this contrast themselves to brewers who fall short in mashing. The properly cooking brewers claim that incompletely cooked sahti can upset stomach.

Perhaps there’s true folk wisdom behind the claim, but I have never tasted so recklessly mashed sahti that it would have disturbed my digestion. A few times I have tasted farmhouse ales with too much active yeast and that can definitely cause stomach churning. Perhaps in the old days, with home-made malts and without thermometers and big kettles, some brewers failed to mash properly.

Draining the Wort

We returned to the brewhouse at 13:30. Now it was time to scoop the mash into the kuurna (lauter tun) and drain the wort out.

When Eila scooped mash into kuurna, the brewhouse was filled with steam. The mash still looked almost boiling. First, she collected 55 L of the first wort and allowed the mash to run dry. Then she began to sparge the mash with boiling water to get the full volume of 123 L.

Eila Tuominen preparing sahti kuurna for lautering
Eila preparing the kuurna for lautering. The wooden props maintain flow space beneath them. In the old days the props were covered with straws and juniper branches, but today Eila uses mesh cloth instead. Note how the kuurna has been charred from boiling mash.
Sparging the sahti mash with juniper infusion
Sparging the mash with boiling water.

Cooling and Fermenting

Eila collected wort flowing out of kuurna into a big bucket and an aluminum milk can. The milk can was immersed in a cold water bath with a constant stream of cold water. Once each canful was cooled, the wort was poured into a storage tank that keeps the wort at 4°C. We left around 16:30 while Eila was still collecting and cooling wort. Normally around 18 o’clock, she would have all the wort collected and cooled.

On this brew day, she brewed only wort, but she told us how she normally ferments sahti: take cold wort from the storage tank and pitch fresh baker’s yeast (1 g/L). Let the wort temperature free-rise to room temperature, around 20-25°C, where sahti ferments around 3 days. When sahti tastes fully fermented and potent, pour it into plastic canisters and store them cold. Enjoy after two weeks of cold maturation.

Although Eila’s fermentation scheme arises naturally from her wort making practices, some sahti brewers intentionally cool the wort well below fermentation temperature before pitching yeast. I think this practice suppresses lactic bacteria usually present in baker’s yeast.

Pouring sahti wort into cooling tank
Eila poured cooled wort into a tank that was originally intended for keeping milk cool. This is a very traditional style tank with a cooling system built around a block of ice and circulating cold water.

Malt Bomb in a Glass

Pertunmaa is in the eastern frontiers of sahti heartlands, and here dark rye malt is more often omitted from the recipe. This gives paler sahti that emphasizes refreshing summery qualities of cereals. Indeed, Eila’s sahti is paler than on average, but I was surprised at its brownish shade, given that the recipe features mostly pale malt and unmalted rye. Surely the extensive mash boil darkens the ale, and perhaps unmalted rye adds color too.

When Eila poured her sahti, the barrage of fresh cereals and sweet maltiness hit my nose. On a hot summer day cold sahti tasted perfect, but when the ale warmed up, it tasted slightly too sweet for me. Eila noted that she likes sweet sahti, and this reinforced my impression that on average women brew a tad sweeter sahti.

When my tastebuds had recovered from the malt attack, I enjoyed the balance of cereals and moderate fruitiness. The banana aroma typical for sahti was fairly subdued. Juniper branches showed up as a delicate side note of Nordic forest.

After the first gulp, the incredibly full body and oily mouthfeel impressed me. Based on the bold mash boil, I expected a slightly less viscous mouthfeel. I still believe that mash boil lightens the body and mouthfeel (though not as much as wort boil) but in this brew a large amount of unmalted rye seem to cancel out the effect.

Eila's sahti
Eila’s sahti looks deceptively plain, but the aroma and flavor are striking.

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