By Laura Burns
Sep 1, 2022
Introduction
Beer trends are fleeting. Some find some staying power, but others never really seem to find solid ground as a crowd pleaser (alas, Brut IPA, we hardly knew ye). As a trend matures, consumers develop expectations for the style’s flavor profile, appearance, aroma, or whatever trait the trend is focused on. Brewers looking to hop on the bandwagon must find a way to meet those expectations, lest their product be considered substandard and left in the dust.
While the haze craze may have once seemed like the stuff of trend chasers, the sales data show that hazy beers are experiencing more year-over-year growth than any other hop-forward style. The time has come to embrace — and perfect — your hazy beers. In this series, we’ll discuss what exactly haze is (and what it is not) plus some insight into our research into dry hopping and the impact of yeast on haze stability to help you dial it in and get a solid, hazy beer every time.
What is Haze?
Examples of varying NTU levels. For comparison, drinking water might measure <2 NTUs, while orange juice may be in the range of 300 – 900 NTUs. It’s no coincidence that most hazy IPAs would measure in a range of 200‑1000 NTUs.
Effectively, haze is turbidity. Some non-beer forms of turbidity are fog or smoke in air. Turbidity is caused by small particles suspended in a medium that obstruct light. Based on the concentration and size of the particles, the resulting haze can vary from nearly clear to completely opaque. We typically expect no turbidity in potable water, but something rather opaque like milk would measure a high level of turbidity.
The image above is a great representation of what different turbidity levels look like to the naked eye. The numbers below each vial refer to nephelometric turbidity units, or NTUs. These units 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
Historically, haze has been beer’s enemy. Brewers have worked for centuries to perfect their methods of preventing haze. Most of our understanding of beer haze revolves around chill hazes and permanent hazes that plague brilliantly bright beer styles like lagers and English ales.
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.
When we talk about haze in beer, we’re referring to the permanent stuff — that milky haze that magically appears 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: too many of these protein-polyphenol interactions and 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. Too few protein-polyphenol interactions and the haze resembles fruit juice and not truly turbid haze.
As our series on haze continues, we’ll dig into experiments we’ve run to learn more about haze optimization, dry hop timing, how yeast contributes to haze stability, and more. Until then, we’ll leave you with a quote to ponder:
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