Lesson 2 - Beer Foam
In this lesson we will discuss the physics and mechanics of foam formation and collapse, along with the chemistry of the compounds involved with beer foam.
Foam is affected by the brewing of raw materials and by wort and beer processing within and outside the brewery. The measuring of foam will be discussed and we will end the lesson by looking at gushing.
Point of Reflection – Reconvene:
Welcome back. So, what were your thoughts?
Any method to measure foam will have limitations. Even as consumers, our perceptions around foam will change depending on the dispense system used, our cultural differences and even our gender. One thing we will not expect in our glass is a disproportionate amount of foam like those generated by these methods.
All these tests rely on the operator to generate a foam head with repeatable consistency, either through pouring or mechanical means. This is difficult to achieve across laboratories.
These methods rely on measuring foam drainage as a marker of foam stability, however, this can be a limiting assumption: beer foam can remain stable after drainage, as seen in nitrogenated products – the Rudin test starts with a degassed beer, so no intrinsic gas effect is measured.
It is also possible to introduce other foam-active material with the injection systems, being either foam-positive or negative.
What brewers wanted was an easy to use, automated and reproducible means of measuring foam stability, such as the Nibem Meter.