What unique yeast fermentation method is typically used in the modern Baltic Porter style?

The unique yeast fermentation method typically used in the modern Baltic Porter style is lager yeast fermentation. This style, which originated in the regions around the Baltic Sea, is characterized by its smooth, malty qualities and relatively low fermentation temperatures.

Lager yeast, specifically the Saccharomyces pastorianus variety, works at cooler temperatures compared to ale yeasts, which helps to produce the clean and crisp character typical of lagers. In the case of Baltic Porters, the use of lager yeast results in a beer that has a rich malt profile with subtle nuances of dark fruit, chocolate, and caramel, while maintaining a smooth mouthfeel. This contrasts with traditional porters, which often utilize ale yeast and are fermented at higher temperatures, resulting in more pronounced esters and phenols.

The use of lager yeast not only contributes to the flavor profile but also affects the overall mouthfeel and clarity, making Baltic Porters a distinct style within the porter category that stands out for its balanced and rounded character.