Lesson 4 - Beer Haze
In this lesson we will discuss beer haze. This will include defining the biological and non-biological (protein-polyphenol) haze types and their formation. We will also identify other hazes that can occur in beer. We will consider the influence of raw materials and discuss processing. To end the lesson, we look at how haze is measured and how we can use accelerated shelf-life testing to predict colloidal stability.
Preface
With some notable exceptions, such as Hefeweizen and New England IPA, the majority of beer drunk globally is expected to be clear (bright) or to have an absence of cloudiness or haze. Bright, clear beer is visually appealing and some consumers reject beer on based on clarity before they have even tasted it.
In this lesson, we explore the nature and types of beer haze, what causes them, and how we measure and prevent their formation. Luckily, the brewer has an arsenal of products and processes they can use to prevent haze formation, or accelerate it to remove the haze before packaging.
To briefly introduce us to the different haze types:
- Biological haze is seen when invading bacteria or yeast multiply to a concentration that introduces haziness into the beer. When this occurs, there may also be a flavour change, such as sourness and sulphury notes due to metabolites being excreted into the beer. Fortunately, with pasteurisation and other techniques for removing microbes, the occurrence of turbidity and off flavour from microorganisms is rare nowadays.
- Non-biological haze formation is a normal event in beer processing and must occur so that the particulate matter can be removed, and the beer can be chill proofed.
Beer haze usually develops over time, so it is important to have predictive colloidal stability tests. We discuss these at the end of the lesson.