Brewer's Ed

Yeast and Haze

Some information and advice to keep your hazies hazy.

By Shana Solarte

May 8, 2023

Haze and its sources

The last two decades have witnessed a sea change in brewer and beer consumer perception of haze. In the US especially, craft beer drinkers have come to appreciate and even expect to see haze in beer. There is even evidence that haze contributes to the aromatic qualities of hoppy beer by solubilizing hydrophobic components of hops. In some beer cultures, however, haze is viewed as the enemy. 

For example, patrons in English pubs have been known to send back a cloudy pint drawn from a cask, and German lager brewers often strive to achieve brilliant clarity without filtration for most of their beers. 

Much of our understanding of beer haze revolves around chill haze and permanent haze:

Chill haze is a haze that forms at colder temperatures when malt proteins and malt/hop polyphenols interact loosely (hydrophobic interactions, hydrogen bonding, Van der Waals forces). This type of haze is reversible. 

Permanent haze occurs when malt proteins and malt and/or hop polyphenols become covalently bonded. This non-reversible haze occurs over extended aging periods or can be forced with repeated cycles of warming and cooling.

So now that we are looking closely at haze, rather than trying to excise it, how do we embrace and perfect it? 

First, some basics:


Figure 1. More NTU means more haze, as demonstrated in the image above.

Effectively, haze is turbidity (see Figure 1). Turbidity is caused by small particles suspended in a medium that obstruct light, similar to fog or smoke in the air. Based on the concentration and size of the particles, the resulting haze can vary from nearly clear to completely opaque. Haze isn’t just a concept — it can be measured. We typically expect no turbidity in our tap water, but something rather opaque like milk would measure a high level of turbidity. Nephelometric turbidity units, or NTUs, help scientists determine objectively the amount of light scattered by these particles. While the measurement may not be all that exciting for beer drinkers, it can help researchers understand how various changes in the brewing process affect turbidity.

Haze in beer

When we talk about the haze in hazy IPA, we’re referring to something closer to the permanent variety— that milky haze that seems to magically appear when buckets of hops are added to the fermentor during fermentation. One popular belief is that this type of beer haze occurs as a result of interactions between malt proteins and hop polyphenols. It’s truly a​“Goldilocks” scenario: if the protein-polyphenol complexes become too large, you get colloidal instability, or what look like fish food flakes swirling around, creating a snow globe effect and resulting in sludge at the bottom of the can. If the protein-polyphenol complexes are too small, they won’t obstruct light and the haze will be minimal. 

Brewers have explored all sorts of methods for manipulating haze, and much of this focus has been on what can be contributed from malt and hops. For malt, increasing protein content by using wheat and other high-protein adjuncts, as well as beta-glucan content from oats, have proved to be a part of the haze equation. Dry hopping is another piece, with the leading theory being that hop polyphenols play an important role in haze development, which is one reason why we tend to associate styles like NEIPAs with haze.

Yeast and haze

There’s lots of talk about how ingredients and process can affect haze, but we want to focus on how yeast can affect haze. Our go-to terminology includes haze positive” to signify strains that could be used to promote haze in a beer recipe and haze neutral” for strains that don’t seem to have much, if any, effect on haze. We got here by running experiments using various strains and subjecting samples to dry hopping at different intervals: knockout, day 1, day 2, and so on all the way up to day 7. 

Key points from these experiments: 

  • Earlier dry hop timing could be a method of removing haze. Flasks with knockout dry hops tended to clear up the sample (and this is true for both haze positive and haze neutral strains). 
  • Mid to late dry hopping promotes haze, in combination with haze-positive strains. Certain varieties of hops create more haze than others (Galaxy, for example). 
  • Haze is not related to flocculation (there are examples of low flocculating yeast that are haze positive and some that are haze neutral). In other words, the haze in hazy IPA is not a result of yeast in suspension. 
  • More dry hops means more haze. The amount of haze was correlated with the size of the dry hop load.

If you think your IPA is not reaching its full potential for haze, consider all of the following variables: 

  • Yeast strain choice (some strains are better at creating stable haze)
  • Dry hop timing (later dry hopping = more haze)
  • Dry hop amount (more hops = more haze)

Consistent performance as haze positive” strains: 
  • British Ale I
  • British Ale V
  • East Coast Ale
  • Hefeweizen Ale I
  • Irish Ale
  • Kolsch I
  • Kolsch II
  • Voss Kveik
  • Scottish Ale
  • West Coast Ale II
  • West Coast Ale III

Need a little coaxing (“haze neutral” strains). These strains will require you to work a bit harder to get stable haze:

  • Bayern Lager
  • British Ale VIII
  • DIPA Ale (Conan)
  • French Saison
  • German Lager I
  • Lutra Kveik
  • Tropical IPA
  • West Coast Ale I (Chico)

Late fermentation dry hopping will definitely help promote haze. Timing your dry hop to be at the tail end of fermentation — when the yeast is still pretty active — can also be a strategy for mitigating hop creep.

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