Sahti, a traditional Finnish beer, is not intentionally carbonated. However, it may have some natural fizz due to the secondary fermentation process. This secondary fermentation occurs in the bottle or keg after the initial fermentation has taken place.
In the production of Sahti, malted barley is usually combined with rye and oats, creating a unique and complex flavor profile. The mixture is then heated in a large wooden vessel called a kuurna, where hot water is added to extract the sugars and flavors from the grains. This process is known as mashing.
After mashing, the wort is transferred to another vessel called a tina, where it is boiled with hops and sometimes juniper berries. The addition of juniper berries is a distinctive characteristic of Sahti, lending it a piney and herbal flavor.
Once the boiling is complete, the wort is cooled and transferred to a fermentation vessel. This vessel can be a wooden barrel or a modern fermentation vessel, depending on the brewer's preference. The yeast is then added, and the primary fermentation begins. During this stage, the yeast consumes the sugars in the wort and converts them into alcohol and carbon dioxide.
After the primary fermentation is complete, Sahti is traditionally served directly from the fermentation vessel, often a wooden barrel. The beer is typically cloudy due to the presence of yeast and other sediments. It is poured into a wooden mug or kuksa, and the natural carbonation from the secondary fermentation gives it a slight effervescence.
The secondary fermentation in Sahti occurs naturally in the bottle or keg, as the yeast continues to consume any remaining sugars and produce carbon dioxide. This process can result in a gentle fizziness, but it is generally not as carbonated as other beer styles that undergo forced carbonation.
I have had the pleasure of trying Sahti during my travels in Finland, and I can attest to its unique characteristics. The lack of intentional carbonation gives the beer a rustic and traditional feel, allowing the flavors from the grains and juniper berries to shine through. The slight fizziness adds a lively touch to the overall drinking experience.
To summarize, Sahti is not carbonated intentionally, but it may have some natural fizziness from the secondary fermentation process. This traditional Finnish beer offers a unique flavor profile and is often enjoyed directly from the fermentation vessel, showcasing its rustic and authentic nature.