Brewing Sahti: An Ancient Finnish Farmhouse Beer
Sahti is an ancient Finnish farmhouse beer that is still brewed much the same way as it was hundreds of years ago. Assured written evidence about sahti goes back only to the 18th century when the value of Finnish folklore was recognized, but from the way it is brewed it is obvious that the tradition is much older. As beer writer Michael Jackson puts it, “Sahti is the only primitive beer to survive in Western Europe.”
The tradition has survived best in the “sahti belt” comprising about 40 towns or villages within two hundred miles radius north of Finland’s capital, Helsinki. In these places sahti is typically a farmhouse homebrew, a craft that has been passed on from generation to generation. Sahti is usually brewed for feasts like weddings, harvest celebrations or even funerals. Every August sahti enthusiasts gather at a yearly national sahti competition, which is organized by The Sahti Society of Finland. There are also relative indigenous beers in Baltic and Nordic countries, such as Koduõlu in Estonia and Gotlandsdricka in Sweden.
In the sahti belt there are also a few commercial brewers specializing in sahti, notably Lammin Sahti (shown in the photo above), Finlandia Sahti and Hollolan Hirvi. Several other Finnish commercial breweries produce sahti occasionally. Because sahti is meant to be consumed within a few weeks from packaging and needs to be stored cold all the time it is rarely exported but with the directions given in this story you can easily brew your own.
Sahti as a Beer Style
Sahti tradition stems from facilities and ingredients of an ancient farmhouse. In the old times sahti was brewed in wooden vessels from homegrown and home-malted grains. Hot water, antiseptic wild herbs like juniper and cold storage were used to prevent souring. No brewer’s yeast or stainless steel was available for brewing. The style guidelines for sahti are best phrased in the European Union Traditional Specialities Guaranteed (TSG) specification: “Sahti is traditionally prepared from raw materials including, in addition to malted barley, other cereal malt and cereals (rye, barley, wheat and oats) and usually hops, fermented using baker’s yeast or harvested yeast.”
This appellation regulates what can be called sahti in the European Union, but it does not limit where sahti is made, only how it is produced. The appellation also specifies that the original gravity of sahti should be at least 1.0785 S.G. (19 °Plato) with extract coming only from malted and unmalted grains. Alcohol content should be 6–12% ABV. “Traditionally prepared” means that sahti is neither pasteurized nor filtered.
Commercial baker’s yeast has been produced since the mid 19th century and during the last hundred years it has been the most common yeast to ferment sahti. Before commercial baker’s yeast, each farmhouse had its own house culture for brewing originating from who knows where. It was often harvested from the fermenter and stored for the next brew. The term “harvested yeast” in the appellation reflects this house culture tradition. German weizen yeast yields similar aromas and flavors as Finnish compressed baker’s yeast, but it is not quite the same, and brewer’s yeast is considered unauthentic for sahti.
Besides the appellation, sahti afficionados have many expectations of what sahti should look and taste like. The appearance of sahti is usually hazy and viscous, still with no head, color typically varying from pale amber to dark brown. Yellow examples exist but many devotees expect darker color. In the aroma and flavor spicy phenols and fruity esters range from low to strong and usually at least some banana is expected. Some tartness maybe associated with fruitiness, somewhat similar to German weizens. Maltiness is sweet and fresh with grainy, bready, worty and porridge-like notes often including notes of dark rye bread. Depending on the brewer, either malt or spicy-fruity yeast character lead the aroma and flavor. Woody, herbal and needle-like juniper character vary from none to pronounced. Traces of herbal hops may be present. Alcohol content is usually 7–9 % ABV. Alcohol warmth is appropriate, but sharp boozy taste is not valued. In some sahti regions slight lactic or acetic sourness is tolerated but usually it is considered a flaw. The body is usually full, often with a smooth viscous milkshake-like palate.
Carbonation should be very low, and signs of carbon dioxide usually indicates that sahti is still unintentionally fermenting. A hint of astringency may be present either from juniper twigs, malt husks or yeast. Some yeast may be suspended but obvious sensation of yeastiness is a flaw. The overall impression is fresh, sweet, malty and nourishing with no sharp edges. Some sahtis can be cloying and the appropriate level of sweetness is a common debate among sahti enthusiasts.
Ingredients
Much of the rustic character of sahti comes from baker’s yeast, which is a strain of Saccharomyces cerevisiae species like brewer’s yeast, but it has not been trained for brewing. Baker’s yeast need not be as pure as brewer’s yeast and most sahtis will eventually turn sour, regardless of the sanitation practices. In fact, Lallemand’s Baking Update newsletter (Volume 1/Number 9) on yeast production states that in the production of baker’s yeast lactic acid bacteria and non-Saccharomyces cerevisiae yeast are always present in minor quantities. Most sahti brewers prefer Finnish compressed baker’s yeast (Rajamäki brand, now owned by Lallemand) but there is little information available on how similar it is to baker’s yeasts from other countries. Besides Finnish compressed yeast, I have used dry baker’s yeast produced in France for Finnish markets and at least this dry yeast produced authentic sahti, though it attenuated further than Finnish compressed
yeast. I suspect that many traits of Finnish baker’s yeast are common to baker’s yeasts in general, like phenolic and fruity tastes, low flocculation, explosive fermentation and traces of souring bacteria.
In sahti substantial maltiness is required, and even gravities below 1.083 S.G. (20 °Plato) can feel lacking. To guarantee rich maltiness and thick mouthfeel I target a gravity range of 1.092–1.101 S.G. (22–24 °Plato). As a base malt, most sahti brewers use Finnish Sahti Malt Blend from Viking Malt. The composition of this blend is proprietary, but a common conception is that this blend is principally Pilsner malt supplemented with pale caramel and diastatic malts. Pilsner malt clearly produces similar results. On the other hand, in the old times farmhouses kilned their malt in wood fired drying barns or saunas, and I wonder if Pilsner malt really mimics rustic farmhouse malt. It is purely my own speculation that Vienna malt or a blend of Vienna and Pilsner would do a better job in this respect. The toastiness and breadiness of Vienna malt certainly fit well in sahti. Either way, both Pilsner and Vienna malts make a good sahti well within modern expectations of taste. Interestingly though, in traditional Finnish drying barns and saunas smoke was an inherent part of the kilning and the malt was certainly at least slightly smoky, but offering a smoky sahti to purists can raise eyebrows. Replacing some of the base malt with smoked malt makes an exquisite sahti but it is a specialty within modern sahtis.
Usually the malt bill contains some rye but it is not a requirement. Most sahti brewers use Finnish kaljamallas (table beer malt), a dark brown rye malt intended for brewing low-alcohol table beer (0–2% ABV) typically served in traditional Finnish canteens and households. This malt imparts a unique soft dark bread taste and it is difficult to substitute. It has a dark brown color somewhat similar to pale chocolate malt but it is barely roasty and the actual color it imparts to beer is closer to dark caramel malts with color around 200 EBC (70-80 °L). Weyermann has a chocolate rye malt, but it is much darker at 500-800 EBC (188–300 °L) and I suspect that it is too roasty. Roasted malts seem to give an inappropriate roasty edge to sahti, which clashes with the spiciness of the baker’s yeast and does not smooth out during the short life of sahti. In the recipe on page 35 I have substituted Weyermann Cararye®, a dark caramel rye malt with 150–200 EBC (57–76 °L) for kaljamallas. I would not say these two malts are similar, but Cararye® does impart some dark rye bread flavors typical for sahti. Kalj-amallas is usually used for 5–10% of the grist and this range is good for Cararye too. This amount also adjusts the color to the typical brownish range.
There are brewers who think that kaljamallas gives too dry and tart of a taste and use pale rye malt instead. It is also a matter of balance; sweeter sahti can hold more dark rye malt. I like to include both dark and pale rye malts, altogether around 15% of the grist, which gives a pronounced taste of rye and an oily mouthfeel. Color and dark rye bread taste come from dark rye malt and then more rye backbone and mouthfeel come from pale rye malt. My decision to use 15% rye is perhaps more than on average, but there are some sahti regions where sahti can contain more than 40% rye malt. Such a high percentage of rye gives a grainy and sourish edge to sahti; it is an exotic but acquired taste.
Smaller amounts of other grains besides base malt and rye are often used for fine tuning. Use of unmalted rye, barley, oats or wheat is fairly common. The included recipe contains 6% of melanoidin malt to enhance bready maltiness and account for the less intensive mash schedule.
Sahti need not contain any juniper, but most brewers want to have a faint juniper aroma and taste. The traditional method is to infuse juniper twigs in hot water, which is then used to clean wooden vessels and sometimes as mash and sparge water. People must have noticed long ago the antiseptic qualities of juniper. Another source of juniper taste derives from the traditional lauter tun “kuurna” where juniper branches and straw are used to make a false bottom. An easy way to mimic these old practices is to add juniper twigs to the mash. Restraint should be used as too much juniper will give a tart, solventy and woody taste with low drinkability. 0.28 oz. (8 g) of twigs to mash for a 5-gallon (19-L) batch gives a delicate but perceivable juniper taste. I prefer the youngest, less woody, top twigs (see photo on page 30). There are several distinct juniper species around the world, the species used in Finland is Juniperus communis. Juniper berries can also replace juniper twigs although the difference is distinguishable, berries giving more peppery and less needle-like flavor. Berries are best added to hot wort or to the fermenter as “dry juniper.” A good starting point is 0.18 oz. (5 g) for 5 gallons (19 L). A fine sahti can be made without any juniper and it is often perceived in sahti even when not actually used, baker’s yeast can give a similar spicy twist.
Hops are occasionally used in sahti, although usually in marginal quantities. A common description of the amount is “a handful of hops” which has hardly any impact in typical farmhouse batch sizes of 13 gallons
(50 L) or more. I use hops occasionally, in which case I add hops to the mash together with juniper twigs with delicate herbal hop varieties preferred. For example, 0.88 oz. (25 g) mash hops for a 5-gallon (19-L) batch gives a delicate background hop note which is still within style expectations, but that is more than most sahti brewers use. Sahti brewers will often also use old, oxidized hops rather than fresh hops.
Other spices besides juniper and hops have probably been used in the past, but these practices have been forgotten several generations ago. For this reason, spices other than juniper and hops are often considered untraditional, although likely some brewers in the past have seasoned their sahti for example with wild rosemary (considered toxic nowadays) or spruce tips.
Process
Most brewers have traditional brewing equipment dedicated for sahti but standard beer brewing equipment also works well. The photos on page 30 show the very traditional gear of sahti master Hannu Siren from Hartola, Finland who has brewed sahti with this kind of setup for 40 years. It is worth mentioning that traditional brewers do not necessarily use hydrometers or thermometers. The temperature and gravity ranges that follow are based mostly on my own experience.
Although most brewers today use commercial malts, mashing times are still typically long — four to six hours — reflecting the old times with less than ideal homemade malts. Often these long mashes are done in several ascending temperature steps, either with water infusions in wooden mash tuns or in kettles, which in the farmhouses are often woodfire heated. After mashing, most brewers scoop the mash into a separate lauter tun called a kuurna. The kuurna is shaped like a long split cylinder and is traditionally made of wood or nowadays also of stainless steel. In the old times straw and juniper twigs were laid on the bottom of the kuurna to act as a false bottom, but stainless steel mesh is often used instead nowadays. The kuurna is then sparged with hot water but sahti is mostly formed from high gravity initial runnings. The later runnings may be collected for a lower strength beer, either to make so-called “ladies’ sahti,” which is still of considerable gravity but only partly fermented, or to make a low-gravity, low-alcohol table beer.
One of the primitive features of sahti is that the wort is not boiled at all or it is just boiled briefly before cooling. Concentrating wort by boiling is not typical. To sanitize wort, some brewers heat or boil the wort for awhile whereas some brewers heat or even boil the whole mash before transferring the mash to the kuurna, which can be done also in a wooden mash tun by adding heated stones to the mash. Ancient brewers must have noticed that when mash or wort was heated close to boiling temperature sahti stored better. From a perspective of modern brewing one might think that these practices would result in a taste of cooked vegetables (DMS) or starch, but these off-flavors will be largely masked by bolder flavors, fresh malt, fruity esters and phenols.
A six-hour mash surely contributes to color and flavor, but with modern malts a shorter mash schedule will also work. I usually mash at 154 °F (68 °C) for one hour and then raise the temperature to mash out at 172 °F (78 °C) for five minutes. Since in sahti wort will not be concentrated by boiling, it takes some practice to hit the desired target gravity. First, the water to grist ratio in the mash needs be low, around 1.105-1.2 qt./lb. (2.2-2.5 L/kg). Second, raising the mash temperature before lautering increases efficiency and wort gravity. This is the reason for the mash out, and even with that I get 70% efficiency at best. Without mash out the efficiency is likely less than 60%. If your mash tun is heated with water infusions, consider raising the final mash temperature with a decotion step (read more about decoction mashing at https://byo.com/story537). Third, lautering and sparging have to be done so as not to dilute the wort below target gravity. Contrary to standard sparging techniques, only a small sparge water volume is used but water temperature can be higher, say 176–185 °F (80–85 °C). Higher sparge water temperature can leach some tannins from the malt, but in a sweet sahti tannins can be a desirable balancing factor. I collect wort until target gravity is reached. Before cooling I heat the wort to 194 °F (90 °C) for ten minutes, which is enough for sanitation. I feel that boiling the wort creates a more beery sahti and detracts from the milkshake-like mouthfeel. Part of the character of sahti is certainly its thick protein-rich texture.
The wort is then cooled and transferred to fermenters. There is no need for a trub separation, and aeration is usually also omitted. In farmhouses, cooling is often done in 10.6 gallon (40 L) aluminum milk cans, which are immersed in a cold water bath, much like how milk was treated before refrigeration. These traditional milk cans are often used as fermenters as well.
With baker’s yeast success depends on finding conditions which favor wanted behavior and suppress unwanted behavior. The main targets are appropriate attenuation, suppression of souring bacteria and sufficient yeast flocculation. Of course, the levels of esters, phenols and alcohols are important as well.
Sahti’s fermentability is largely determined by pitching temperature, fermentation temperature, and timing of transfer to cold conditioning. Typical apparent attenuation range of sahti is 62–72%. At the lower end sahti can feel overly sweet and worty, and at the higher end it can feel boozy, unpleasantly tart and watery. For the recipe below the sweet spot is around 65%.
Many sahti brewers start fermentation at room temperature, around 64–77 °F (18-25 °C), let sahti ferment about 24 hours and then move the fermenter to a cooler place to retard further attenuation. At temperatures below 55 °F (13 °C), sahti will continue to ferment slowly and usually finish at higher gravity. In my opinion this method is hard to do consistently as at room temperatures baker’s yeast will ferment explosively and can finish dry in less than two days. Another downside of this practice is that unpredictable fermentation may occur in the final containers. Important safety note: If you are a homebrewer who uses bottles rather than kegs you must make sure your sahti is fermented to the finish or risk exploding bottles. Remember, when we prime regular beer we control the new fermentable that we add, and thus the pressure that is created. With this sahti we don’t know how many fermentables are left at bottling time.
I prefer to start fermentation at 61–63 °F (16–17 °C) and ferment to finish at 61–66 °F (16–19 °C). These temperatures restrain fermentation and seem to prevent too high attenuation. The lower end of this temperature range gives a cleaner taste usually with lower attenuation and at the higher end fruitiness becomes pronounced. A target of 64 °F (18 °C) seems to be a sweet spot, at least for Finnish compressed yeast.
The fermentation takes about three days but I keep the temperature steady for an extra day or two. Allowing the yeast to finish before cold conditioning results in faster flocculation and avoids problems with fermentation in the final containers. On the other hand, sahti should be cooled as soon as possible, as warmer temperatures favor souring bacteria. If these colder fermentation temperatures result in lower attenuation than desired, I recommend adding a short aeration step next time, about one third of the standard beer aeration.
After initial fermentation, sahti is cold conditioned for at least a week, traditionally in a ground cellar or cold storage room. To suppress souring bacteria, conditioning should be done at least below 51 °F (11 °C) with 32–41 °F (0–5 °C) preferred. This is because Lactobacillus needs a minimum working temperature of 51 °F (11 °C); below that temperature it will die. If you are bottling, keep the temperature well below 51 °F (11 °C) to be safe. Baker’s yeast is a poor flocculator and dropping out the bulk of the yeast is the primary reason for cold conditioning. To further avoid yeastiness, I recommend racking your sahti to a secondary fermenter after initial fermentation.
After cold conditioning, the sahti is racked to containers. Sahti is not purposely carbonated but sometimes baking yeast can re-ferment and build pressure in the containers. For this reason, containers where you can easily release pressure are preferred. Sahti can also be kegged and pushed out with CO2, but avoid storing sahti under pressure. Store sahti cold all the time and plan to consume it within few weeks. Storage below 41 °F (5 °C) can substantially extend the lifetime of your sahti and, conversely, even half a day at room temperature can kick off sour fermentation. In any case, sahti often turns sour within a month or two from packaging.
Sahti is usually served at cold storage temperatures and at temperatures below 46 °F (8 °C) sahti often feels more balanced and refreshing. But well-made sahti is tasty over a wide range of temperatures and is devilishly drinkable, hence the saying, “sahti knocks the unwary off his feet.” Don’t be afraid to experiment!
Top: After mashing, most brewers scoop the mash into a separate lauter tun called a kuurna.
Bottom: A traditional wooden mash tun used for sahti.
Top: In the old times straw and juniper twigs were laid on the bottom of the kuurna to act as a false
bottom.
Bottom: A traditional wood-fire-heated kettle, which is used for making authentic Finnish sahti.
Sahti
(5 gallons/19 L, all-grain)
OG = 1.097 FG = 1.034
IBU = 0 SRM = 18 ABV = 9.2%
Ingredients
8.8 lbs. (4 kg) Pilsner malt
8.8 lbs. (4 kg) Vienna malt
1.76 lbs. (0.8 kg) Weyermann rye malt
1.32 lbs. (0.6 kg) Weyermann Cararye® malt
1.32 lbs. (0.6 kg) Weyermann melanoidin malt
0.28 oz. (8 g) juniper twigs (added to the mash)
1.1 oz. (31 g) fresh compressed baking yeast or 0.46 oz. (13 g) dry baking yeast
Step by Step
Dough-in at 154 °F (68 °C) using around 1.15 qts. of water to one pound of grain (2.4 L/kg). Add juniper twigs to mash. Hold at this temperature for one hour. If using a heated mash tun, raise temperature to 172 °F (78 °C) for 5 minutes. Sparge slowly with 180 °F (82 °C) water, collecting wort into the kettle until a target gravity of 1.097 is reached. Since the wort will not be concentrated by boiling, be careful not to dilute the wort below the target gravity. Heat the wort in the kettle to 194 °F (90 °C) and hold for 10 minutes. Chill the wort to 63 °F (17 °C). Transfer the entire wort to the fermenter. Because the wort is not boiled there is no trub. If you are using dry baking yeast, hydrate the yeast in 104 °F (40 °C) water, as you would do with dry brewing yeast. If you are using fresh compressed yeast, liquefy the yeast in a small amount of 63 °F (17 °C) water. No aeration is needed.
Ferment at 64 °F (18 °C) until fermentation is complete. This should take about three days. Keep the temperature steady for an extra day and then chill the fermenter to 32–55 °F (0–13 °C), the cooler the better. After two days of cold conditioning, rack your sahti to a secondary fermenter. Cold condition for another week before racking into containers.
Sahti
(5 gallons/19 L, partial mash)
OG = 1.097 FG = 1.034
IBU = 0 SRM = 16 ABV = 9.2%
Ingredients
6 lbs. (2.7 kg) rye liquid malt extract
6.6 lbs. (3 kg) Pilsen liquid malt extract
1.32 lbs. (0.6 kg) Vienna malt
1.32 lbs. (0.6 kg) Weyermann melanoidin malt
0.28 oz. (8 g) juniper twigs (added to the mash)
1.1 oz. (31 g) fresh compressed baking yeast or 0.46 oz. (13 g) dry baking yeast
Step by Step
Heat 1 gallon (~4 L) of water to achieve a mash temperature of 154 °F (68 °C). Add juniper twigs to the mash. Hold at this temperature for one hour. Sparge slowly with 1 gallon (~4 L) of 180 °F (82 °C) water. Add hot water and liquid malt extract, adding water into the kettle until a target gravity of 1.097 is reached. Heat the wort in the kettle to 194 °F (90 °C) and hold for 10 minutes. Chill the wort to 63 °F (17 °C). Transfer the entire wort to fermenter. Because wort is not boiled there is no trub. If using dry baking yeast, hydrate it in 104 °F (40 °C) water, as you would do with dry brewing yeast. If you are using fresh compressed yeast, liquefy the yeast in a small amount of 63 °F (17 °C) water. No aeration is needed.
Ferment at 64 °F (18 °C) until fermentation is complete. This should take about three days. Keep the temperature steady for an extra day and then chill the fermenter to 32–55 °F (0–13 °C), the cooler the better. After two days of cold conditioning, rack your sahti to a secondary fermenter. Cold condition for another week before racking into containers.
Tips for Success:
Juniper tips were traditionally used for more than flavor when making sahti. The twigs were laid on the bottom of the kuurna to act as a false bottom. You can recreate this method at home by laying juniper twigs in your mash tun. Use restraint, however. Too much juniper flavor in your sahti gives a tart, solventy and woody taste.
