Sahti, a farmhouse beer style indigenous to Finland, is one of the oldest beer types still brewed today. Sahti is top fermented, unfiltered, unpasteurized, and turbid with an original gravity of at least 19°P and at least 6% alcohol by volume, with the most common alcohol content being between 7% and 8% by volume. See plato gravity scale. The color may vary from pale yellow to dark brown. Sahti should have a pronounced banana-like aroma and taste slightly sweet, with little hop character. Some examples have a clear indication of rye and juniper in the taste.

Sahti is a relic of an ancient Finnish rustic brewing tradition. It is still brewed much the same way as it was some 500 years ago, to be consumed at weddings and other festive occasions. The sahti heritage is strongest along the “sahti belt,” which runs through the old provinces of Satakunta and Häme, a few hundred kilometers north of Helsinki. “Suomen sahtiseura” (the Sahti society of Finland) keeps the tradition alive and arranges a yearly sahti competition for home and farmhouse brewers.

Close relatives to sahti exist on some Baltic islands. Gotland, Sweden, has a farmhouse brew called “dricku” and Saaremaa and Hiiumaa (Estonia) have “koduõlu.”

The first modern commercial sahti brewer, Lammin Sahti, in Lammi, Finland, started brewing in 1987. In 2010 half a dozen commercial sahti brewers held a license to sell their beers and a handful of microbreweries occasionally brew commercial sahti as well. After sahti received worldwide attention through the writings of beer author Michael Jackson, the interest in brewing sahti has spread to other parts of the world, notably the United States. See jackson, michael.

In Finland, farmhouses and homebrewers brew sahti in small volumes, often with traditional equipment. Commercial brewers use modern stainless steel brewing vessels, but their brewing procedure still follows the traditional principles.

It takes the small-scale brewer about 20 kg (44 lb) of grain and 50 g (1.6 oz) of compressed baker’s yeast to produce around 50 l (13.2 gal) of basic sahti. The grain bill contains malted barley and other malted and/or unmalted grains: rye, wheat, oat, and barley, according to the specific recipe. A commonly used grain bill contains about 90% malted barley and 10% malted rye, but old hands have been known to use an even higher proportion of rye, up to 40%. A small amount of hops and juniper (Juniperus communis) may be added, usually by boiling them and spicing the brewing liquor with the resulting solution. See juniper.

The mashing procedure is a form of temperature-programmed infusion mashing. Hot water is added to the mixture of malt and cereals either in batches of rising temperature or all at once and heated in the mash tun. The traditional vessel used is the “muuripata,” a wood-heated built-in cauldron, which is standard equipment for heating water in a Finnish sauna. At the start of mashing, the temperature is around 40°C (104°F), and it is increased gradually to 70°C (158°F). Mashing schedules usually have rests at about 50°C (122°F) and just below 65°C (140°F). There may be one more rest at about 75°C (167°F) as well. Some brewers use single-temperature mashing at a temperature of 65°C (140°F). (Old sahti masters do not use thermometers; they measure the temperature by their fingers and the tip of the elbow.) In some recipes the mashing ends with boiling, which is achieved by different methods and can be short or long in duration. One way to bring the mash to boiling point is to immerse heated stones in the mash. The end product might then be called “kivisahti” (stone sahti). This method is ancient, reaching back to a time when people did not have metal vessels. See steinbier.

After approximately 4 h of mashing, the mash is strained. Traditionally this happens in the “kuurna,” a trough-like vessel with a false bottom of rye straws and juniper twigs, with or without the berries, boiled to make them sterile. Although now usually made of stainless steel, the trough shape of the kuurna recalls the vessel’s origins as a hollowed-out aspen log. The mash, which may be quite porridge-like, is transferred to the kuurna and sparged with hot water. After collecting the high-gravity part of the wort the brewer may ferment that separately, but continue sparging and use the secondary low-gravity batch to make a “naisten sahti” (“ladies’ sahti,” the name being as ancient as the style). After the run-off is over, the spent grains from the mash make a flavorful ingredient for bread. Some brewers do not boil the wort but others do, especially if the brewer wants to concentrate the wort to reach a higher gravity.

At one time, sahti, like all ancient beer styles, was spontaneously fermented, but this sort of fermentation is no longer performed. Today, the correct fermenting agent for sahti is either commercial baker’s yeast or simply harvested yeast from a previous batch (of course, commercial baker’s yeast may differ from country to country, but it is quite consistent within Finland). The main fermentation is very vigorous and usually lasts roughly 3 days. The secondary fermentation takes at least 1 week, preferably more.

Sahti should be stored in cool surroundings and consumed within a few weeks. If properly stored, commercial versions have a shelf-life of 2 months. The traditional drinking vessel for sahti is a wooden cup called a “haarikka,” which is often passed around, particularly in the sauna.

Because sahti is a farmhouse beer, most variables in sahti brewing are adjustable according to the brewer’s fancy, as long as the minimums of the original gravity and the alcohol content are kept; only baker’s yeast or harvested yeast is used and the alcohol comes exclusively from the sugars in the grain bill.

Sahti has a certificate of specific character for agricultural products and foodstuffs (TSG) in European Union.

See also finland.