Ale and lager are probably the most common types of beer there is. Despite its fame, it is still unclear to many the difference between the two.
The most common difference is that ales have a fruity-estery taste while lagers taste crisp. But, the significant difference between the two doesn’t lie in its character, rather in how and what yeast is added during the brewing process. So, let’s take a closer look at how yeast sets these two apart in terms of colour, body, aroma and taste.
1. Yeast Strains
First and foremost, two different yeast strains are responsible for the unique characters of ale and lager, respectively, thus distinguishing them from one another.
Ales are fermented using strains of Saccharomyces cerevisiae while lagers are fermented using strains of Saccharomyces pastorianus. Ale yeast or Saccharomyces cerevisiae is one of the commonly used yeast strains in baking bread. On the other hand, Saccharomyces pastorianus or lager yeast is unique and is used only for brewing. In addition to its fondness for cold, Saccharomyces pastorianus is known for its ability to metabolise two of the complex sugars found in grains – raffinose and melibiose, which Saccharomyces cerevisiae don’t have the power to deal with.
Ales undergo warm fermentation while lagers are fermented cold. Ales mostly ferment at a temperature of 60–75°F (16–24°C) but can up to 95–100°F (35–38°C) depending on the kind of saison strain. On the other hand, lagers are fermented at a low temperature of 45–55°F (7–13°C). But it should be duly noted that lagers are capable of fermenting at high temperature just like ales. The reason behind lagers’ cold fermentation is twofold. Firstly, lager yeasts thrive in the cold and secondly, cold fermentation can supress the unwanted by-products that come with yeast fermentation. This contributes to its crisp, clean character.
However, there are exceptions to this. Some lager yeast strains perform extremely well in warm temperatures while few ale yeast strains are very comfortable at lower temperatures.
When brewing lager beer, cold-conditioning, is a common practice after fermentation. Ales generally do not undergo this process. Cold-conditioning, otherwise known as lagering, is an essential phase in brewing lager for the following reasons:
- Initiates secondary fermentation which in-turn carbonates the beer
- Improves the flavour
- Allows yeast the settle out
- Prevents oxidation
- Prevents haze formation after filtration, when the beer is chilled
For the same reasons, it goes without saying, that conditioning is important for all types of beer.
Understanding the basic contributing factors behind ale and lager, such as the ones mentioned above, can help you understand your beers better. And the next time you drink ale or lager, you can appreciate all the ingredients, brewing process and hard work that goes into crafting different beers with unique characteristics. Not to mention, the intellectual demeanor you exude while talking to your friends about everybody’s favourite beverage.