The Haze Complex

In a liquid like beer, when particles that are originally invisible to the naked eye group together, they show up to us as cloudiness — or turbidity. This is haze. 

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 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 working on capturing haze as they do refining for clarity. 

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 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 important to understand there are multiple sources for haze in beer. 

Though malt, yeast and hops each have independent haze-determining factors, 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. 

There are a handful of sources for haze originating 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 the 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 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: 

Balancing proteins and polyphenols 

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 things to consider: 

Researchers found that when haze-active proteins and polyphenols were present in about the same proportion, they could combine well to create large molecules that appear as haze. But if proportions were imbalanced, haze tended not to form because the more abundant compound tended to get in the way, keeping the relevant binding sites apart. 

When the system is cold and slower-moving, the large protein-polyphenol polymers that do form tend to stay bonded together, but when the system is more energetic (warmer) they fall apart, breaking up. This is what is thought to create the phenomenon of chill haze.

Sometimes, however, instead of falling apart, the same protein-polyphenol bonds can strengthen and form permanent haze. Things like repeated changes in temperature, pasteurization, light irradiation, oxidation, age and vibration during storage and transport can cause temporary haze to become permanent. 

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. 

Minimizing malt haze

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

Here are some common approaches:

First, brewers could 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 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.

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).

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.

Some people still associate yeast haze with poor yeast health. Think propagations and fermentations lacking nutrients, temperatures that are too high, 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. But what other brewers suspected, but no one really knew about for sure until now is that yeast is responsible for a ​“good” kind of haze, too — the rich, colloidal kind that brewers actively want for hazy styles. It has to do with the fact that fermentors are now regularly loaded up with hops. What do hops have to do with it? There is a yeast-determined haze produced by healthy yeast in conjunction with hop compounds. Hop compounds seem to interact to increase or decrease the haze that ​“haze positive” strains put out. 

This yeast-determined haze is proving to be a 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. Some strains have way more haze potential than others, so strain choice is important. 

Strains that have haze ability are called haze-positive. They can both create haze and be restrained from it, which makes them versatile for any haze outcome. Haze-neutral strains don’t have significant yeast-contributed haze levels. So, they’re good for safeguarding bright styles, so you don’t have to battle against yeast haze to get the clarity you want. 

This experiment was designed to illustrate the differences in haze outcomes when dry hop timing varied with a haze-positive strain (British V) and a haze-neutral strain (West Coast Ale I).

For each series, we inoculated nine identical flasks of wort with the same yeast on the same day, and then dry hopped them at different times during fermentation.

• The control flask was not dry hopped.
• The central flasks were dry hopped on progressive days (day zero, one, two, three, four and seven).
• The last was double dry-hopped — half early in fermentation and half late.

Can you spot which is which?

Which series was fermented with British V (very haze positive) and which with Chico aka West Coast Ale I (haze neutral).

TIP: look for increasing haze with later dry hop timing to find the haze positive strain. 

Early dry hop, double dry hop

Dry hopping at the same time as pitching yeast resulted consistently in an additional clarifying effect, even when there was also a later dry hop, for both haze-positive and haze-neutral strains.

When helping brewers troubleshoot a hazy beer that mysteriously dropped clear, we’ve sometimes discovered a dry hop was moved up, or a hop product was changed. These are both things that can affect haze.

TIP: If you’re having haze problems with the strain you’re using for your West Coast IPA, try a small dry hop load at yeast-pitch (¼ lb/bbl).

Sorting strains by haze potential

The amount of haze that any strain generates is not so much a yes-no binary as an a‑little-to-a-lot spectrum.

In testing, if a yeast strain could cause more than 200 NTUs of turbidity when the wort was dry hopped on day seven of fermentation (this is when it should be contributing its maximum haze potential), we considered that strain to be haze-positive. If it didn’t, we categorized it as haze-neutral.

Other hop variables that affect haze levels with haze-positive yeast 

We’ve seen additional elements of the dry hop also affect the intensity of yeast-derived haze with haze-positive yeast. Any of the following can also amplify or diminish haze:

• Hopping rate: More hops, more haze. Haze increases along with higher hopping rates. 
• Hop variety: Different hop varieties seem to enable yeast-determined haze differently.
• …And more: Differences between concentrated lupulin pellets and hop extracts are likely to make a difference, too. There are a lot of variables introduced by different hop products. 

What have you noticed changes haze outcomes in your recipes? 

We’ve described two ways hops have a supporting role in haze — they can add polyphenols to protein-polyphenol polymers, and dry-hopping can trigger haze with haze-positive yeast — but there is something else about the dry hop that is impacting haze that’s independent of the yeast type, too. 

It might be linked to differences in polyphenol composition between varieties, or it may be something else entirely — something that we haven’t uncovered yet: 

We used a late-fermentation dry hop in 15 fermentations where the variable was hop variety — first with a haze positive strain, then with a haze neutral strain. We measured haze output for both. 

Some hops were able to help promote haze even with haze-neutral strains. This complexity across varieties suggests that dry hopping leads to multiple forms of haze. 

Here you can see that haze varies differently in haze-neutral fermentations than it does in haze-positive fermentations. That’s a good illustration that this hop haze is working independently of the haze that shows up in conjunction with haze-positive yeast. 

Galaxy was one of the hops that made extremely hazy beer in combination with haze-positive yeast, but did not produce much haze at all with a haze-neutral yeast. Other hops, like Columbus, promoted haze to a lesser degree with haze-positive yeast, and could still lead to haze with haze-neutral yeast. 

Knowing which hop and yeast best promote or reduce haze are another thing you can consider for reliably hazy or non-hazy beers in recipe design. In our experiments, for example, we saw that for haze Galaxy and British V are a great pair. And for a bright style, like a West Coast IPA, Simcoe and West Coast Ale I are good at keeping haze minimal.