The beer that undergoes the most fermentation is typically ale. Ales are known for their top fermenting process, where the yeast used rises to the top of the fermentation vessel during fermentation. This process usually takes place at warmer temperatures compared to lagers. As a result, ales tend to have a more robust and complex flavor profile.
During the fermentation process, yeast consumes the sugars in the wort (unfermented beer) and converts them into alcohol and carbon dioxide. The yeast used in ales is known as Saccharomyces cerevisiae, which is a top fermenting yeast. This yeast strain is highly efficient at fermenting the sugars, producing alcohol, and creating the characteristic flavors and aromas associated with ales.
One of the reasons ales undergo a more pronounced fermentation compared to lagers is the yeast's behavior during the process. Top fermenting yeast tends to be more active and vigorous, resulting in a faster fermentation process. This increased activity leads to a higher production of yeast esters and other flavor compounds, which contribute to the unique taste of ales.
Personal Experience: As a brewer, I have witnessed the vigorous fermentation of ales firsthand. The fermentation vessel would often be filled with a thick layer of yeast, creating a frothy and active environment. The aroma that filled the brewery during ale fermentation was incredibly enticing, with fruity and spicy notes wafting through the air.
Another factor that contributes to the extensive fermentation of ales is the higher temperature at which they are fermented. Ale yeast strains typically thrive at temperatures ranging from 15-24°C (59-75°F). These warmer temperatures allow the yeast to work more rapidly, leading to a quicker fermentation process.
In contrast, lagers undergo a bottom fermentation process using a different yeast strain known as Saccharomyces pastorianus. Lager yeast prefers cooler temperatures, usually fermenting between 7-13°C (45-55°F). This slower and colder fermentation results in a cleaner and crisper flavor profile, with fewer yeast-derived flavors compared to ales.
To summarize, ales, with their top fermenting process and higher fermentation temperatures, undergo a more pronounced and vigorous fermentation compared to lagers. This leads to a greater production of yeast-derived flavors and a more complex flavor profile in the finished beer.