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.
Relative Merits of Process Aids
In the previous unit on beer ageing and finishing, you learnt about processing aids in detail. Many of these sold to brewers are to enhance colloidal stability. Let us summarise these below:
Table: Processing aids for haze prevention
|
Process Aid |
Ingredient |
Charge |
Point of Addition |
Target |
Mode of Action |
|
Kettle finings |
Carrageenan |
Negative |
Wort kettle |
Proteins |
Precipitation |
|
Isinglass finings |
Collagen |
Positive |
Maturation |
Yeast |
Precipitation |
|
Silica gels |
Polysilicic acid |
Negative |
Maturation |
Proteins |
Adsorption |
|
Tannic acid |
Gallotannin |
Negative |
Maturation/filter |
Proteins |
Precipitation |
|
Enzymes |
Papain Proline specific endo protease |
Maturation Fermentation |
Proteins |
Non-specific hydrolysis Site-specific hydrolysis |
|
|
PVPP |
PVPP |
Maturation or filter |
Polyphenols |
Adsorption |
|
|
CSS |
Agarose |
Negative |
Filter |
Polyphenols |
Adsorption |
The majority of larger brewers globally use one or more of these processing aids. This is especially true of beers with longer shelf-life. For beers requiring a shelf-life of 12 months or greater, a combination of treatments targeting both proteins and polyphenols is often used, typically silica gels and PVPP.
The advantages and disadvantages of using process aids are as follows:
Advantages
-
Produce a long-lasting colloidally stable beer
-
Possibility to optimise and shorten maturation times
-
Removal of protein can reduce subsequent soiling of vessels and pipework
Disadvantages
-
Cost of material and cost and complexity of dosing
-
Need to optimise dosing rates to ensure optimal effect while avoiding processing issues, beer loss and even hazy beer!
-
In some parts of the world, labelling may be a requirement
What could you do to reduce the polyphenol content of your beer to reduce the chances of the beer developing a chill haze?
Give yourself 5-10 minutes to think about this, and then click ’Next’ to continue with this lesson.