Bottom fermenting yeast, also known as lager yeast or Saccharomyces pastorianus, is a type of yeast that plays a vital role in the fermentation of certain beers, especially lagers. This yeast is called "bottom fermenting" because it ferments at lower temperatures and sinks to the bottom of the fermentation vessel during the fermentation process.
Bottom fermenting yeast is characterized by its ability to ferment sugars and produce alcohol and carbon dioxide. It is called "yeast" due to its classification as a single-celled fungus and its ability to convert sugars into alcohol and carbon dioxide through the process of fermentation. The temperature range required for fermentation with bottom fermenting yeast is typically between 7 and 13 degrees Celsius (45 and 55 degrees Fahrenheit), which is considerably lower than the temperature range for top fermenting yeast used in ale production.
Compared to top fermenting yeast, bottom fermenting yeast thrives in cooler temperatures and exhibits a slower fermentation process. This slow and steady fermentation process, which can take several weeks or even months, allows for the production of crisp, clean, and well-rounded flavors in lagers. It also contributes to the characteristic smoothness and clarity of lager beers.
In addition to the fermentation process, bottom fermenting yeast is also responsible for imparting certain characteristics to the beer, such as its aroma and flavor profile. Different strains of bottom fermenting yeast can produce distinct flavors, ranging from mild and neutral to fruity or spicy. This versatility allows brewers to experiment with various yeast strains to create a wide range of lagers with different flavor profiles.
In summary, bottom fermenting yeast is a type of yeast that ferments sugars at lower temperatures, sinks to the bottom during fermentation, and is mainly used in the production of lagers. Its slow
