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.
Point of Reflection – Reconvene:
Welcome back. So, what were your thoughts?
There are actions that you could take throughout the process, including raw materials, the brewing process and the use of process aids.
Raw material options could include the use of proanthocyanidin-free barley malt (with caution), but there may be better options when looking at the hop products and hop point of additions used. Hops contain polyphenols, so it is best to use hop products that do not contain polyphenols, such as some hop extracts and limiting the amount of hops added post wort boiling (such as dry hopping). The boiling process helps to polymerise and precipitate the polyphenols in beer, so adding hops after the boiling process can lead to polyphenols being dissolved directly into the beer.
Check that your mash pH is in the accepted range of 5.2 to 5.4 to encourage polyphenol precipitation and that the mash is handled gently to prevent polyphenol extraction from the malt in the first place.
Although oxygen can be detrimental to flavour stability, it can help polymerise polyphenols and help ensure it is precipitated or filtered out of the beer. Undertake aeration during wort cooling to prevent the negative impact on flavour stability.
Cold maturation at the right temperature (<0°C) allows the protein-polyphenol complexes to increase in size and gives them sufficient time to precipitate out of the beer or to be removed by filtration.
The use of PVPP as a filter aid or using a CSS stabiliser can remove/significantly reduce polyphenols from the final beer, thus helping to prevent the formation of chill haze.