The Haze Complex

When the goal is rich colloidal haze as opaque as milk or orange juice — haze that makes a beer’s body appear to glow when lit, and that sticks around smoothly in suspension — particles have to be of certain sizes and composition. That’s not always so easy to orchestrate. 

Brewers spend just as much time these days capturing haze as they do refining for clarity. But for all the attention hazy beers get, the exact mechanisms for haze are not well understood. Omega Yeast is helping to change that. 

Omega Yeast’s researchers have discovered some new levers, some in combination with yeast (and some despite it), that can help you to control both haze and clarity practically. To do that, it’s first important to understand there are multiple sources for haze in beer.

Malt, yeast and hops each have independent haze-determining factors. And leaning on haze that forms in one way rather than another could make your beercraft significantly easier. Whether you’re clearing haze or building it, knowing what’s driving it will save you from uphill battles and fruitless effort. Perhaps surprisingly, that starts with your yeast.

There are a handful of sources for haze that originate from malt inputs to wort and beer. Some significant ones are carbohydrates — like long-chain dextrins not broken down during the mash, and β‑glucan, which is a viscous, gummy fiber mostly derived from malt barley (or other cereals, like oats). Its gummy quality can be a production nightmare. 

Another significant haze source from malts are proteins and polyphenols. Protein-polyphenol haze is probably the most significant haze-contributing factor on the malt side. Proteins (from malts), and polyphenols (from malts and hops) can join up and create larger-sized polymers. A smaller subset of malt proteins are haze-active (like hordein). They have amino acids (like proline) at certain bonding sites, which attract polyphenols more actively (like proanthocyanidins, and various diverse catechins). Different malts and malt products, and other factors (like mash temperature) affect how much haze-active protein and polyphenol content ends up in wort. The way the component particles bond under certain conditions defines whether the haze will be stable in beer over time. 

Protein-polyphenol haze sticking around in the way brewers want depends a lot on balance:

‎ON MALT-RELATED HAZE

Setting the stage for haze based on protein-polyphenol linkage can be a little hairy. Too little of some things or too much of others, and it can fail to show up like we want it to (if we want it to). Here are some ways haze based on these malt-derived components can show up and disappear in ways we’re not expecting:

• Proportions: when haze-active proteins and polyphenols are present in about the same proportion, they combined best to create large molecules that show up as significant amounts of haze. But, surprisingly, if proportions are very imbalanced, whether skewed toward one or the other, haze tended not to form well because the more abundant compound tended to get in the way, keeping the relevant binding sites apart.

• Chill haze: when the system (wort or beer) is cooler, it’s slower-moving, and large protein-polyphenol polymers that form tend to stay bonded together. And when the system is more energetic, i.e. warmer, they can also fall apart, which resolves what’s then known as chill haze. What starts off as a temporary haze can also strengthen and form permanent haze. Things like repeated changes in temperature, pasteurization, light irradiation, oxidation, age and vibration during storage and transport can cause even temporary chill haze to become permanent haze instead of clearing up.

• Haze gone chunky: Protein-polyphenol bonding can also be so successful that the size of the polymers tips over to colloidal instability, resulting in the haze going chunky and falling out.

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ON MALT-RELATED CLARITY

Trying to get rid of protein-polyphenol and other malt-influenced haze? Some best-practices — and clarifying agents — can help:

• β‑glucan: First, try avoiding malts with high β‑glucan (and protein) content. But for dealing with β‑glucan, lower mash ranges can help break them down.

• Proteins: Proteins can be more difficult: yeast needs soluble protein (FAN), but too much can create off flavors and too many proline-rich proteins can lead to haze.

• Polyphenols: For polyphenols, care in malt handling, like avoiding high temperatures and high pH in the mash and lauter, and steering away from over sparging, can keep you from over extracting from the malt (barley husk is loaded with polyphenols).

• Clarifying and fining: 
  • Hot-side clarifying agents are often used to remove malt proteins and polyphenols in the kettle. Fining agents, such as carrageenan and PVPP are helpful in removing hot break and separating trub. Cooling the wort quickly helps remove cold break.
  • In the cellar, adding proline-specific endopeptidases takes proline-rich malt proteins (haze-active proteins) out of the mix before fermentation (like barley hordeins, and wheat gliadins).
  • Post-fermentation, adding silicic acid can further remove proteins — and yeast. PVPP can be added post-fermentation to get rid of more polyphenols.

One kind of yeast haze that is a signal of something very wrong in fermentation is from poor yeast health: propagations and fermentations that are lacking the right nutrients, temperatures that are too high, and cells damaged by autolysis or sheared by pumps and centrifuges — haze that’s linked to yeast’s cell-wall β‑glucans, mannans and/or glycogen from cell ruptures, and the like. Some people still associate yeast haze exclusively with poor yeast health. That’s a misconception (it’s not yeast in suspension, either). 

We now know there’s another way yeast determines haze. Yeast is also responsible for a rich, colloidal kind of haze that brewers actively want for hazy styles. It comes from healthy yeast — and some strains more than others. The appearance of this kind of haze has a lot to do with the fact that fermentors are regularly loaded up with hops. 

Yeast-driven haze is produced in conjunction with hop compounds. And elements of hops’ compounds seem to interact to increase or decrease the haze that yeast strains put out. Some strains have way more haze potential than others, so strain choice is important when planning, whether for haze or for clarity. 

Yeast-determined haze is proving to be an incredibly reliable way to keep a solid foundation of stable haze when you want it — or a crucial way to remove obstacles to clarity when you don’t.

ON YEAST-RELATED HAZE (FROM HEALTHY YEAST)

• To maximize haze, make sure you’re using a haze-positive yeast strain. Yeast strains that have significant haze-forming ability were named by Omega Yeast’s researchers as haze-positive. These strains can both create haze AND be prevented from it, which actually makes them versatile for any haze outcome. 

• Understand when they produce the most haze to lock down your hazy-style profile easily. Use them with later-in-fermentation dry hopping and certainly avoid any early dry hopping. 

• In addition to dry hop timing, hopping rate, hop variety, and other hop factors can deliver more haze intensity. There are also differences in haze that are created when using concentrated lupulin pellets or hop extracts, for example.

ON YEAST-RELATED CLARITY

When maximizing clarity is your goal, dry hopping a small amount at the same time that you begin fermentation results consistently in an additional clarifying effect of healthy yeast’s yeast-determined haze (see this early-fermentation dry hop experiment), even for strains that may be contributing only small amounts of haze — that means for haze-neutral strains, too; an early dry hop charge promotes clarity from healthy yeast’s yeast-determined haze, no matter the strain. 

But to circumvent dry-hop timing as a factor entirely, some brewers use their favorite strain with its haze-determining gene removed altogether. This neutralizes a haze-positive strains’ ability to make the substantial yeast-determined haze they’re known for, and it also reduces the relatively little amounts of haze a haze-neutral strain can be contributing, too.

We’ve already described two ways hops have a supporting role in each of the other sources of haze — 1. they can add polyphenols to protein-polyphenol polymers, and 2. dry hopping factors can trigger haze with haze-positive yeast. 

But there is something else about the dry hop that is impacting haze independently from the yeast type. There appears to be an independent hop-driven haze. It might be linked to differences in polyphenol composition between varieties, or it may be something else entirely.

ON BOTH HOP-RELATED HAZE AND CLARITY

Knowing which hop and yeast best promote or reduce haze is another thing you can consider for reliably hazy or non-hazy beers in recipe design. Check out the experiment at the link below, where you can see that haze varies differently in haze-neutral and haze-positive fermentations. That’s a good illustration that there’s a hop haze working independently of yeast-determined haze.

TAKEAWAYS

Malt, yeast and hops all have important lead roles to play in different, cumulative sources of haze. And it matters where the haze is coming from if you want to be able to control it. 

In terms of reliability, consistency and ease of process, a haze-positive yeast strain will do the most to lay a foundation for successful haze. And a haze-neutral strain is going to go a long way in paving the way for clarity (or a haze-positive strain with the right dry hop timing).

Above you’ve read a lot about what you can do to understand how to control haze and clarity better. But that’s not ALL you can do — Omega Yeast researchers found the actual gene responsible for yeast-driven haze in yeast, and named it HZY1. Its discovery means they can create new yeast tools and technologies for brewers. Clarity-optimized strains like a super juicy non-hazy and a Chico…fino already exist from Omega Yeast as a result. 

What’s coming next are likely new hazy options — familiar strains that were previously best for bright styles, but are now good at hazy ones. That will mean more opportunity for some brewers to diversify their hazy profiles just by having their core ingredients doing more. 

Stay tuned. There’s more to come thanks to HZY1!