Lesson 2 - Warm and Cold Maturation
This lesson explores the processes of warm maturation and cold maturation. Warm maturation can also be described as flavour maturation This process removes negative or unwanted flavours from the beer post-fermentation. Cold maturation occurs at lower temperatures (below 0°C), which in turn causes haze-forming components to form. These components can then be removed by precipitation or clarification via centrifuge or filtration. This lesson highlights the importance of these processes, how they affect the quality of the final product, and how we manage these maturation steps.
Preface
In this lesson, we will describe the range, design, and capabilities of a maturation system and consider how these factors help us to achieve successful beer maturation.
Objectives of beer maturation
At the end of fermentation, the beer is often referred to as ‘green beer’ (‘green’ does not actually refer to the colour of the beer). Beer maturation is thus the process of converting the ‘green beer’ into beer that is either ready to package and serve, or beer that is in its final stage prior to clarification. Based on this, the key objectives are to:
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Control the temperature and yeast count of the beer to either completely remove or achieve the desired levels of ‘green beer’ flavours, such as diacetyl and acetaldehyde (warm maturation).
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Provide the ideal conditions for chill haze formation (colloidal stabilisation) as well as their precipitation and removal from the beer (cold maturation).
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Create the opportunity for final beer flavour, aroma and colour additions to the beer.
A beer’s colloidal stability refers to the non-biological hazes formed by the interactions between the beer’s polyphenols and proteins, causing visible precipitates to form. Beer with high colloidal stability has a low potential to form these hazes or precipitates.
It is also possible to increase the beer’s carbonation levels by using fermentable extract and yeast during the maturation stages. However, as this can be achieved with in-line dosing, it is not a core requirement of beer maturation.
So, as the above maturation objectives show, the maturation system must ensure these requirements are met. We will now identify the maturation system design features that help support these processes.