Yeast are responsible for carrying out the fermentation process of the wort, converting sugars into carbon dioxide and alcohol and there are loads of different kinds of yeast, all used for specific beer styles.
All yeast used in the process share similarities in morphology, functionality, reproducibility, and ability to ferment the wort. However, yeast also have slight differences between each of the strains used for brewing, which end up contributing subtle differences to the final beer.
The world of yeasts is so wide and diverse that brewers and amateurs have basically classified beers into two large groups according to the type of fermentation they carry out. Thus we have ALE beers (high fermenting yeasts) and LAGER beers (low fermenting yeasts).
The main difference between ALE and LAGER beers lies in the temperature at which the yeasts ferment and where they do it in the fermenter. ALE type yeasts ferment at higher temperatures (15-25°c) and do so from the surface, while LAGER type yeasts ferment at lower temperatures (10-13°c), and do so from the bottom of the fermenter. Pilsner beer is also a type of Lager beer.
First off: What is yeast, and what is its function?
Yeast is a unicellular fungi microorganism that is carefully isolated and selected through technological processes in order to use it to carry out the fermentation process in beer brewing.
Yeast has the ability to reproduce rapidly if the environmental conditions are favorable, and even when brewing beer, they often reproduce so many times that the initial yeast population triples, or more.
These microorganisms, in the first stage, in the presence of oxygen and other micronutrients begin to reproduce sufficiently to cope with the amount of sugar present in the wort to be able to process it.
When the oxygen is totally consumed by these yeasts, the second stage begins in which the sugars present in the wort are converted into carbon dioxide and alcohol.
In addition to generating these main compounds, the yeasts also generate sub compounds that impart special characteristics to the beer, such as esters, phenols, fatty acids, etc., which end up giving a wide range of profiles and flavors to the beer.
What is an “Ale” beer?
ALE beers belong to the top-fermenting yeast family, that is, yeasts that ferment in a range of 15 to 25 degrees Celsius and do so at the top of the fermenter.
The yeasts used in this type of beer are called saccharomyces cerevisiae and work from the top of the fermenter which happens because the yeast cells are smaller, being dragged by carbon dioxide bubbles to the surface and remaining suspended there until fermentation is complete, at which point they drop to the bottom.
ALE beers complete primary fermentation in a relatively short period of time, ranging from 2 to 5 days. The maturation or conditioning process is also short and takes 7 to 15 days.
The temperature at which the beer ferments can result in distinctive flavors, at the upper end of the temperature range, more esters and phenols will be produced, giving fruitier and spicier characteristics, while the lower range will produce cleaner and lighter beers, with less fruity characteristics. In general, ALE beers have more complex flavors and aromas compared to LAGER beers.
Ale yeast and its characteristics
- Type of fermentation: ALE yeasts ferment on the surface of the wort, remaining suspended there until fermentation is complete. Also known as top-fermenting yeasts.
- Temperature: between 15 to 25 degrees Celsius.
- Fermentation time: 2 to 5 days.
- Type of flavors they contribute: ALE yeasts contribute more esters generated by the combination of alcohol and organic acids present in the wort, which imparts fruity notes to the beer, such as notes of banana (wheat beers), apple, honey, etc.
Types/Styles of Ale Beer
This Ale family is composed of dozens of styles, but the most popular ones are:
- Pale Ale: Born in England around 1620, this beer style is characterized by its balance between hops and malt. It is not tipped to either extreme.
- IPA: India Pale Ale (IPA) style beers are characterized by a strong aromatic profile and intense bitterness. The protagonist of this beer are the hops, and the floral notes and aromas depend on the type of hops used during brewing.
- Wheat Beers: Whether they are German Weissbier, American Wheat Beer, Belgian Witbier, Weizenbock or Dunkelweizen, these beers made from wheat usually present refreshing characteristics, and depending on the style, they can be spicy in aroma, with a moderate breadlike wheat flavor.
- Stout and Porter: Both beers share some characteristics, such as a roasted and malty aroma. However, an important difference between the two is the coffee notes of the Stout, while in the Porter style beers the chocolate characteristics stand out.
- Blonde Ale: It is a pleasant golden beer, with a nice body to it, malty with cereal, with biscuit and wheat flavors. It has moderate bitterness and fruity aroma, with hints of pineapple and a distinctive white, creamy and long-lasting foam.
What is a Lager beer?
LAGER beers are fermented by saccharomyces pastorianus yeasts, they ferment at a lower temperature (between 8 and 12 degrees), and unlike ALE beers, they ferment from the bottom of the fermenter because the cells are larger and heavier.
LAGER beers have a fundamental and characteristic stage that differentiates them from ALE beers: After fermentation, LAGER beers have a storage period called LAGERING. This stage consists of keeping the beer in cold storage, close to 0 degrees Celsius but without it freezing, for a prolonged period of time ranging from 1 to 3 months.
This long-term cold storage, or lagering, allows the yeast to consume residual sugars and digest by-products left over from the primary fermentation process, such as sulfur compounds.
All this makes it possible to obtain light, clean beers, with a crystalline color and high drinkability. Pilsners are an example of this type of beer. They were the first LAGER beers developed in the city of Pilsen, the Czech Republic in 1842, marking the beginning of the success of LAGER beers that we observe today.
Lager yeast and its characteristics
LAGER yeasts are unicellular microorganisms called Saccharomyces Pastorianus. They are able to break up sugar chains that ALE yeast cannot, resulting in LAGER-style beers having a much lighter mouthfeel.
Also, the low fermentation temperatures inhibit the production of esters and phenols, giving the beers a clean profile, without spicy and fruity notes derived from the yeast.
However, the fermentation process at lower temperatures can result in sulfur compounds (rotten egg smell), so good fermentation temperature management and extended conditioning are critical to achieving a light, clean profile with these beers.
Types/Styles of Lager Beers
Within the group of LAGER beers, there are various types that depend on characteristics such as the density of the wort, the hops used, the grain blend, and other characteristic elements of its elaboration.
- Pilsner: Pils, Pilsner or Pilsener, is the best known type of LAGER beer worldwide. It originates from the city of Pilsen, in the Czech Republic. This type of beer is generally very mild, its aroma is hoppy and its characteristic color is light golden.
- Helles: Helles beers are less hoppy than Pilsners, less dry, and at the same time more full-bodied. They are a little darker in color but have the same alcohol content.
- Dunkel: These are the beers known as dark lager in Germany. They generally contain more malt than pale beers, which gives them their characteristic dark color. They also contain a more significant amount of hops to counteract the bitterness of the malt.
- Bock: Bock is a style of strong lager beer. They can be dark or light, depending on their multiple variants such as Doppelbock, Maibock, and Weizenbock, among others. They are generally made of barley, however, there are also some with a portion of wheat, giving them a particular flavor.
- Märzen: This type of beer is also known as Oktoberfest since it is usually brewed in March to be stored until October when it is drunk at the beer festival. They usually have a bronze or copper color, and in terms of alcohol content, they have more than pale lagers but less than bock beers.
What is a Pilsner beer?
Pilsner is a beer belonging to the LAGER family (bottom-fermenting yeasts), with its origins in the Czech Republic, near the region of Bohemia. What characterizes Pilsners is that they are blonde beers, quite light and translucent in color, very bright, light, and with high drinkability.
Characteristics of Pilsner beers
In flavor and aroma, we find malt and little presence of hops. They are light, refreshing, with lots of bubbles, lots of foam, and with a very simple objective that they almost always fulfill: to refresh.
Due to these characteristics, Pilsners are known to be the ideal type of beer for hot days. They also have a medium alcohol content (around 5% ABV) and their slight bitterness of between 30 and 40 IBUs makes them very easy to drink.
Pilsner Beer Types/Styles
Pilsners are usually divided into three styles according to the BJCP (Beer Styles Manual): The German Pilsner, the Bohemian Pilsner, and the American Pilsner.
German Pilsner: Its distinctive properties are a slight Pils malt character and a characteristic floral or spicy aroma from the noble hops. Clean, without fruity esters or diacetyl.
Bohemian Pilsner: The Bohemian Pilsner style is Rich and complex, combining malt complexity with a smooth, Saaz hop presence, providing bitterness and a spicy flavor coming from this hop type. Some diacetyl may be present, although it is not necessary. Bitterness predominates, but should not be aggressive and it also does not linger.
American Pilsner: This is a version of Pilsner brewed in the USA using ingredients native to the USA. These beers contain up to 30% corn or rice as adjuncts. They have a discreet grain sweetness due to the use of corn to offset the bitterness of the hops. The hops used are noble and of medium to high bitterness, but without being aggressive or leaving a sharp aftertaste. It is a smooth, well-matured beer.
Is there a difference in taste between Lagers and Ales?
Yes, ALE beers have the particularity of offering more complex flavors, more estery, with an appreciation of fruity, floral, spicy, phenolic notes, and perhaps a more pronounced final sweetness, while LAGER beers are cleaner and drier, and there is more maltiness, they are generally not as bitter, lighter and refreshing.
What is the most common type of beer?
Starting in 1842, LAGER beers began to gain ground over ALE beers. The development of Pilsner Urquell beers imposed this type of beer in the market, probably because of their high drinkability, and for being simpler in taste and aroma to the palate.
This is why in the industrialized beer market, the common denominator of beers we find is the LAGER type and not so much Ale.
Do home brewers use Ale or Lager yeast?
Homebrewers generally produce Ale beers because fermentation temperatures are easier to control and do not require sophisticated refrigeration equipment to succeed. This is because Ale beers ferment at around 22 degrees Celsius whereas lagers require a temperature generally below 12 degrees.
In addition, ALE beers are more complex and allow for a little more innovation in beer profiles and flavors.
Conclusion
LAGER beers dominate the industrialized beer market, and it could be said that ALE beers predominate in the production of small-scale “Craft” beers.
Within LAGER beers we would expect to find beers with greater drinkability and a cleaner profile in flavors and aromas, while in ALE beers we would expect to find a more complex profile of aromas and flavors, with fruity, floral, and spicy notes.
Frequently Asked Questions
Is ale or lager stronger? Lager beers tend to be lighter and smoother usually contain fewer hops, and the alcohol content is in the 5-proof range. However, within lager beers, there may be exceptions, such as bock beers, which are quite strong. Still, ale beers are overall the stronger type of beer.
Is Heineken Lager or Ale? Heineken is a LAGER beer, because it is brewed with bottom-fermenting yeasts, and it is conditioned at really low temperatures for long periods of time, as are all beers in this category, which is why Heineken has a smooth and soft flavor.