Sahti: A traditional Finnish farmhouse ale

Beer writer Michael Jackson helped introduce sahti to the world through his books and articles, but the beer has a very long tradition — so much so that he called it the “only primitive beer to survive in Western Europe.” Recent interest in traditional Scandinavian brewing has further stoked the interest of brewers, as has general interest in farmhouse beers. Yet since examples are difficult to find, many craft beer drinkers have only a passing understanding of the style. Sahti is most commonly associated with two signature ingredients: Juniper and rye.

One point of confusion among many craft beer drinkers is when something is called a farmhouse beer. Too many people seem to think this means spontaneous fermentation and a barnyard character, but neither of those are correct. It simply means that the beer was traditionally made by farmers at the farm using materials at hand, like the grain they grew and sometimes malted. Like turning milk into butter, farmers turned grain into beer for their own use. Gradually, industrialization replaced this tradition of farmhouse beers, but sahti is one of the few remaining instances of this type of beer production.

This style was introduced to the Beer Judge Certification Program (BJCP) style guidelines in 2015 under category 27, Historical Beer. If there ever was a historical beer to include, this is it. I was only able to put together a style description for this beer at the time because of writings Garrett Oliver had done that included sufficient sensory details to make judging possible. Since then, several books and articles by Finns such as Mika Laitinen have both confirmed and expanded on this starting point.

Sahti History

There are many kinds of farmhouse beers in Scandinavia and Baltic countries, as well described in the excellent book Historical Brewing Techniques by Lars Marius Garshol. Sahti is only one of them, but it has some fairly unique characteristics and production methods. Just don’t think that because we are focused on sahti that other countries in the region don’t have a similar tradition – they do, but they all have their own unique methods and ingredients.

While sahti is from Finland, current production seems to be most concentrated in southwest Finland. The brewing tradition is ancient, since before the Middle Ages, certainly before modern brewing was understood. Much of the history is based on folklore tradition, so calling it a “Viking Age beer” is not inaccurate. The excellent paper Physiochemical Characterization of Sahti from the Institute of Brewing and Distilling (IBD) mentions that sahti was first described in detail in 1780, and was ancient then. Despite the lack of historical evidence, there is currently a surprising agreement on the basic outlines of the style.

The farmhouse brewing tradition followed the development of agriculture, so even in the post-Ice Age world in Nordic countries, this would be ancient – at least to the first millennium C.E. Advancements were introduced, of course, but primitive conditions and remote locations would certainly constrain the pace of change. The style predates the use of hops in beer, but juniper serves a similar role. Home malting died out by the 1960s, so commercial malts are now used. House yeast was also largely replaced by commercial baker’s yeast in the 20th century.

Sahti is a strong beer, so it is considered a beer for special occasions like weddings, feasts, and seasonal celebrations. Commercial breweries have made this in Finland since the 1980s, but it is historically a homebrew from the farm. Traditionally produced using farm equipment, commercial breweries still try to use the historical procedures to make this type of beer while employing their current equipment.

Sensory Profile

There is enormous variation in the beer from brewer to brewer, so the sensory profile also has to be somewhat broad. While the European Union (EU) created a definition as part of making it a protected appellation, the requirements are equally broad. The EU describes it as an unpasteurized, unfiltered beer of 19 °P (1.079 SG) or more original gravity, 6–12% ABV, pH less than 5, using baker’s not brewer’s yeast, having a slightly sweet taste, and being a yellow to dark-brown color.

Much of the history is based on folklore tradition, so calling it a “Viking Age beer” is not inaccurate.

The IBD scientific article provides some good insight into the sensory profile of the beer since they analyzed many examples. They describe it as a strong and sweet beer, with a high original gravity and a high finishing gravity. The beer has a fruity or floral yeast profile from fermentation, and 4-vinyl guaiacol (4VG, or clove flavor) is above the flavor sensory threshold. The beer is turbid, orange-red in color, and has no foam. Carbonation is low, but not completely still. Bitterness was measured at about 9 IBUs on average. The pH on average was 4.4, so it is similar to common beer. But the high residual gravity shows there are a lot of unfermented sugars present. The beer is unusually thick and viscous due to the lack of a boil and the use of rye.

Other references mention the juniper character as green and fresh, foresty, woody, pine-like, with some citrus notes, possibly moss-like and minerally. Michael Jackson called it minty, but that is not a descriptor used elsewhere. The juniper gives a smooth and rounded bitterness, since the hop bitterness is below sensory threshold and there is no hop flavor or aroma. The flavor is more of juniper branches than its berries; the well-known component of gin’s character. Other spices were probably used in the past, but those have been lost to time.

Malt flavors include worty sweetness, some caramel and toffee flavors, maybe some nuttiness. Rye can contribute some graininess and add a touch of dryness, maybe a light spiciness. There should not be roast, burnt, or smoky flavors. Yeast flavors are fruity, and banana-like, with some spicy phenols.

The mouthfeel deserves some discussion. Some have said the beer is thick, like a milkshake. I would say full body and high viscosity. The carbonation is natural, and low like in a British cask ale. The alcohol strength is significant, but in a low bitterness, sweet beer, it may be covered up. Alcohol can be warming, but the beer should not seem boozy. The beer should not be sour or acidic; Finns consider sourness a fault, and a sign the beer is too old. Michael Jackson described sahti as smooth, soft, and drinkable on the palate.

The color of the beer can vary wildly, from yellow to dark brown. Reddish-amber colors were often mentioned as being desirable. With low carbonation, the beer should not have any significant foam. The high final gravity, high protein content, and poorly flocculating yeast make the beer hazy and turbid.

Brewing Ingredients and Methods

This beer can be difficult to produce, especially if authenticity is your goal. Most brewers will make reasonable substitutions to obtain a facsimile of the original, but even in Finland modern brewers produce the beer with current equipment yet using traditional procedures. I will try to talk about the range of options, so this section will be longer than in most of my articles.

Traditional grains used would be what was grown on the farm. Barley, of course, was used, but rye was also common. Oats and wheat could be used, but that is not common now. Grains are typically malted. In modern times, most Finns have switched to Viking Sahti malt, a proprietary commercial blend of at least three malts. Brewers there have suggested that a blend of Pilsner and Munich malts is an acceptable substitute (maybe 80–90% Pils malt, and 10–20% Munich malt). Rye is usually no more than 10% of the grist, and can be malted rye, dark rye, or even rye flour. Vienna malt appears in some recipes as well; it is certainly a solid choice here. Sugar adjuncts are never used.

There is a commercial dark rye malt in Finland, but this isn’t exported. I would use something like Weyermann rye malt, and maybe add some other malts for more flavor. Some have suggested adding caramel rye malt, and this isn’t a bad idea. I might try to bring in more flavor by using a bit of dark Munich malt, which is not traditional but is attempting to substitute some more developed flavors. Toasting commercial rye malt could be used as well, maybe toasting the malt at 350 °F (180 °C) in the oven until it turns a more golden-brown shade.

In traditional times, malt would have been dried at the farm and the malt would have had a smoky flavor, typically using alder or birch wood. However, modern examples using commercial malts do not have this character, and the beer is not considered to be a smoked beer so I would stay clear of adding yet another complex flavor to the mix. I mention this only because I have tasted some interpretations that are smoked and I wanted to point out that regional sources have said this is not a smoked beer.

As an ancient style, mashing was complicated and not based on scientific understanding but rather practical experience and what was possible using available equipment. A long mash, upwards of six hours, was common. It started very thick (perhaps around 1.2 qts./lb. or 2.5 L/kg) and was heated either through infusions or the additions of hot stones to the mash. The stones could add some caramelized flavors, but this is not a requirement of the style. I do think it helps justify the use of caramel rye malt, however. Decoction is another alternative, but I would avoid boiling the grain since it might make lautering difficult.

In the old times, straw and juniper twigs were laid on the bottom of the kuurna (equivalent to a lauter tun) to act as a false bottom for sahti production. The mash would be scooped into the vessel after several hours of mashing, often in the range of four to six hours. Photo by Mika Laitinen

Mash rest temperatures were often not documented as scientific measurement instruments were not traditionally used. Modern practice seems to start in the protein rest range of around 122 °F (50 °C) although some can start as low as 86 °F (30 °C). Mashing continues until at least 158 °F (70 °C). Since the wort is not boiled, mashing may continue as high as 176–194 °F (80–90 °C). Bringing the mash to a true boil is not done since this makes lautering even more difficult than it is. But the high mash-out temperature is believed to improve the stability of this beer.

Lautering traditionally is done in a hollowed-out log using boughs of juniper as a filter. The shape of the lautering vessel is therefore long and narrow (see photo on page 26), which would help keep the mash from being too deep. Modern versions can be made in mash tuns using false bottoms, but often use juniper as well. As an alternative, juniper can be added to the mash tun or steeped in the strike water. The juniper must be fresh and green, and is often not too mature. Some have described the branches as having a diameter smaller than your finger. The branches may or may not have berries attached. The species of juniper is usually Juniperus communis, which is not common in the U.S. – be careful with substitutes since some juniper species are toxic.

I have used Colorado Blue spruce in other beers in a similar manner, and steeping the branches in the brewing liquor is an interesting idea. Steep the branches for two to three hours in 176–194 °F (80–90 °C) water, then strain. Don’t boil the wood, since this will provide an unpleasant bitterness and astringency to the finished beer. Since the mash program goes through similar temperatures, just adding the branches to the mash can serve a similar purpose. Juniper berries have a different flavor than the branches and are not a substitute. Berries are optional, but can have a more aromatic quality.

At the farmhouse, brewers would reuse their yeast by top-cropping and often drying the yeast. Some used wooden chains to collect and store the yeast. It was certainly not spontaneously fermented. The use of Finnish baker’s yeast is current practice; Suomen Hiiva is the brand. This yeast is different from North American baker’s yeast. It is fruity and banana-like, is POF+ (phenolic off-flavor positive, so it has a clove flavor), is not a good flocculator, and may have a little lactic acid bacteria present. Sourness is not desirable in this style, so the beer has to be handled properly to avoid developing sour flavors.

Some have suggested using kveik yeast, since it is often of Norwegian origin. That could be interesting, but most kveik yeast are POF- so the flavors won’t be the same. If you don’t like clove flavor in your beer, kveik is a good choice and ferments fast. One such yeast was found to actually be a Bavarian weizen strain, so I think that makes a reasonable substitute to the Finnish baker’s yeast. If you find a yeast that is fruity, has a banana flavor, produces some clove, and ferments fast, it should work. But if you described that type of yeast to me, I think I’d call it a weizen yeast. So outside the EU, I would try a dry German weizen or Belgian wheat yeast rather than something like Fleischmann’s bread yeast or whatever is found at your grocery store. I would also shy away from the classic Weihenstephan 3068-type yeast since it is so clearly associated with hefeweizen-type beers. Something with more fruit flavors than banana is OK.

Fermentation practice in Finland seems to be to start cold and then allow to warm. Since the wort is unboiled, this is probably another precaution against spoilage. Traditional farm yeast was used at warmer temperatures, but since baker’s yeast has been used the temperatures are lower. Pitch below 50 °F (10 °C) and allow it to rise to room temperature as it begins to work. Fermentation is typically fast, often in less than three days. A cool secondary fermentation for up to a week is often used, and the beer is then stored cold (like you would for milk). It is often not stable, so should be consumed soon. Also the resulting beer is not primed, so whatever natural carbonation is present is acceptable.

Hops are often used in a symbolic form, almost like in lambics. Low alpha varieties can be added to the mash as a protection against spoilage, but they don’t add detectable aroma, flavor, or bitterness. Brewers often don’t measure them; you see recipes describe adding a couple handfuls of cone flowers to the mash. If you have any older, oxidized hops, here might be a place to use them. Since the wort is not boiled but the mash is very long, I think adding them to the mash is the correct procedure. The variety doesn’t really matter, so I would probably select low-alpha, noble-type European hops like Saaz or maybe Spalt. Some versions are unhopped, but I think hopping is a good precaution.

None of the references I consulted mention anything about brewing water, so I would just use fresh, clean, low-mineral water. Tell yourself stories about it coming from a glacier, if you like.

Homebrew Example

Not much additional to say here since I described the various options previously. I’ll just put them into practice. The grist is Pilsner, dark Munich, CaraRye®, and rye malt, all Weyermann, and in the proportions common for the style. Some Spalt hops at about 9 IBUs gives me an average bitterness for the style. Since I’m using rye malt, I’ll use some rice hulls to help with the lauter.

I use a four-hour multi-step mash, recirculating and direct heating the mash on my system. The recipe calls for resting but it also can be made with a slowly increasing temperature throughout the mash, as long as the total mash time is the same. Don’t dilute the mash too much since the wort will not be concentrated by boiling; think of this as a first runnings beer.

Dry weizen yeast will have to do since I can’t get Finnish baker’s yeast, and I’m using a cool ferment. I’m shooting for about a 9% beer. One day I hope to make it to Finland to see how close I got.

Sahti by the numbers

OG: 1.076–1.120
FG: 1.016–1.038
SRM: 4–22
IBU: 0–15
ABV: 7–11%

Gordon Strong’s Sahti

(5 gallons/19 L, all-grain)
OG = 1.099 FG = 1.038
IBU = 9 SRM = 16 ABV = 9%

15.5 lbs. (7 kg) Pilsner malt
2 lbs. (0.91 kg) dark Munich malt
2 lbs. (0.91 kg) rye malt
1.25 lbs. (567 g) caramel rye malt (65 °L)
1 lb. (454 g) rice hulls
4 AAU Spalt hops (mash hop) (1 oz./28 g at 4% alpha acids)
1–2 small Juniperus communis branches to cover the mash tun
LalBrew Munich Classic, SafAle
WB-06, or a favorite kveik yeast of your choice.

Step by Step
This recipe uses reverse osmosis (RO) water. Adjust all brewing water to a pH of 5.5 using phosphoric acid. Add 1 tsp. of calcium chloride at the beginning of the mash.

This recipe uses a long, multi-step infusion mash, but no boil. The wort is not concentrated by boiling so think of this as a first-runnings beer. Mash in the grains with the rice hulls at 113 °F (45 °C) using 1.2 qts./lb. (2.5 L/kg) of water. Add the hops then hold for 30 minutes. Raise the temperature to 122 °F (50 °C) and hold for 30 minutes. Raise the temperature to 131 °F (55 °C) and hold for 30 minutes. Raise the temperature to 140 °F (60 °C) and hold for 30 minutes. Raise the temperature to 149 °F (65 °C) and hold for 30 minutes. Raise the temperature to 158 °F (70 °C) and hold for 30 minutes. Add the juniper to the mash. Raise the temperature to 167 °F (75 °C) and hold for 30 minutes. Raise the temperature to 185 °F (85 °C) and hold for 30 minutes.

Run off the wort slowly into the fermenter until you have collected 5 gallons (19 L). You many need to sparge lightly if necessary to reach this volume. Brew-in-a-bag users may have an advantage since they can wring out the wort from the grains as well. Using a larger fermenter is advisable since the fermentation can be vigorous.

Chill to 50 °F (10° C) and pitch the yeast. Allow the temperature to rise to room temperature as the fermentation gets going. When fermentation starts to slow, rack the beer gently to secondary and move to a colder location, 50 °F (10 °C) or below. Condition for one week. Try to avoid removing carbonation from the beer during transfers.

Keg without additional carbonation, or package in plastic soda bottles. Do not prime. Since the beer is biologically unstable, you will want to store below 40 °F (5 °C) and preferably consume within two weeks.

An extract recipe is not possible due to the unusual brewing technique of sahti and the fact that much of the character of the beer comes from the wort production.

Tips For Success:
While sahti is beer produced from the first runnings from the kuurna, or lauter tun, the remaining sugars would not be wasted. Traditionally a second runnings beer would be fermented to produce a table beer or “ladies sahti.” If you have the fermentation space, it seems prudent to collect these sugars and make one yourself as there will be plenty of sugars remaining in the mash.

If you cannot source fresh, green juniper branches, then you can substitute in juniper berries as well, which will provide more of a black-pepper kick compared to the pine needle-like branches. According to Mika Laitinen, adding 0.18 oz. (5 g) berries per 5 gallons (19 L) of beer directly to the fermenter (like dry hops) is a good starting point. He also adds that: “A fine sahti can be made without any juniper and it is often perceived in sahti even when not actually used, the baker’s yeast can give a similar spicy twist.”

Issue: November 2021