Types of Beer Fermentation: Here's What They Are

Types of beer fermentation: here are which ones.

The types of raw materials used (malts, hops and/or flavors), the brewing patterns adopted, the type of fermentation (low, high or spontaneous) as well as the generations of yeasts used directly influence the final product, and therefore the taste, aroma and richness of the finished product.
In this article, we'll explore the different types of beer fermentation and learn how they're used to create beers with unique flavors and aromas.

What is beer fermentation?

Fermentation is the heart of the brewing process, a very delicate stage during which the wort, obtained from the raw materials, is transformed into beer. It is a chemical-physical and, above all, biological reaction, made possible by yeasts which, once introduced into the wort, feed on the sugars, amino acids and other substances present, releasing compounds such as ethanol, CO₂, esters, higher alcohols, organic acids and hundreds of other components that contribute to the taste and aroma of the beer.
Fermentation is a self-contained process, but factors like temperature and oxygenation strongly influence the final result.
There are three main types of fermentation, each with its own characteristics and uses:

Low fermentation

It uses yeasts from the Saccharomyces uvarum, pastorianus or carlsbergensis family.
These yeasts generally work between 7 and 9°C , and are characterized by a relatively slow fermentation process (7 to 10 days).
Once fermentation is complete, the yeasts settle at the bottom of the fermenter (hence the name "low fermentation").
The resulting beers are often more neutral, clean and balanced . This type of fermentation is used to produce beers such as Pilsner or Weissbier .

Top fermentation

It uses yeasts from the Saccharomyces cerevisiae family, which work between 12 and 23°C .
Fermentation is faster (about 7 days).
The yeasts remain on the surface once the process is complete (hence "high fermentation").
The beers produced often have strong, fruity, and complex aromas . This type of fermentation is used for Ales and Stouts .

Spontaneous fermentation

This is a rarer method, using yeasts naturally present in the environment , such as those in the air.
Typical of Lambic beers , it gives rise to beers with an acidic, complex and unique taste.

Craft beers can then undergo, depending on needs, a second or even a third fermentation .

How does beer fermentation take place?

The fermentation process is divided into three phases :

  • primary fermentation

  • secondary fermentation or hot maturation

  • cold maturation
    After this, a refermentation in the bottle can possibly take place.

Primary fermentation

This is the first step. The yeast, introduced into the cooled must, first consumes oxygen to produce sterols, essential for cell membrane growth.
Once the oxygen is consumed, the yeast switches to anaerobic mode, where it transforms all the sugars in the wort into ethanol and CO₂ .
This step determines a large part of the organoleptic characteristics of the beer.

Secondary fermentation or warm maturation

It occurs when the majority of sugars have been metabolized.
At a higher temperature than primary fermentation, this stage allows the yeast to eliminate diacetyl , a substance harmful to aroma.
Flocculation also occurs: the yeasts clump together and fall to the bottom of the fermenter.

Cold maturation

This phase occurs after the beer has reached its final density.
The tanks are cooled to 0°C , allowing the yeasts to continue settling.
Conditioning time depends on the beer style.
The cold causes the precipitation of protein/polyphenol complexes , which clarifies the beer and refines its aromas.

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