What are Polyphenols?
Polyphenols are a group of flavor-contributing compounds introduced from grain and hops. They contribute flavor, astringency, perception of bitterness, haze, oxidative effects, and antioxidative effects. Like a model built from LEGO®* blocks, polyphenols are made up of smaller phenols that link together.
Your friend just poured you a fresh homebrew, and it came up cloudy. How do you feel about hazy beer? Is it good? Is it bad? Do you even care?
Some might say it depends on the beer. After all, certain styles are supposed to be cloudy. Others may think that hazy beer is never appropriate, while still others might prefer to remain neutral and drink up regardless of clarity. Why should you care about cloudy beer? You can’t taste haze—or can you?
Whether haze is purely cosmetic or flavor-altering, the only way to do anything about it is to first understand it.
Why Is My Beer Hazy?
Most homebrewers face beer haze after brewing and fermentation are complete, and haze can be an indicator of a few issues. The first is related to suspended yeast, and the second is caused by a combination of protein and polyphenols.
Of course, we know yeast is in beer. In some cases, yeast rapidly settles out as fermentation comes to a close, while in others, it remains suspended even when the beer is chilled. A yeast cell’s desire to bind to other yeast cells to form flocs (clumps of yeast that tend to settle out quickly) is called flocculation. Thus, choosing a yeast with good flocculation characteristics tends to produce beer that clears quickly, while selecting a less flocculent strain means that your yeast might hang around in the beer for longer than you’d like. Picking a flocculent strain is a good way to promote beer clarity.
If you’ve removed the yeast, the remaining cause of haze is usually from protein and polyphenols, and most professional operations spend a lot of resources combating this type of haze. Why? Because polyphenols can contribute to oxidative staling reactions. However, polyphenols come from beer ingredients and occur naturally and universally in beer. So complaining about their presence is a bit like complaining about salt in seawater—unless you accidentally take a big gulp or get it in your eye (the seawater, not polyphenols), you have to accept it and figure out how to work around it.
In extreme cases, haze can completely cloud your beer (e.g. wheat beers). In less extreme cases, proteins and polyphenols might produce a more subtle haze. Some haze, known as permanent haze, is visible even when beer is at room temperature. Another, known as chill haze, doesn’t appear until the beer is cooled, which can be somewhat maddening because the cloudiness disappears and reappears.
But beer haze can also indicate a more sinister problem: bacterial infections, which can cloud beer and ruin it with off-flavors. For example,Pediococcus damnsosus is a common brewery infection that generates large amounts of diacetyl, that unwelcome buttery taste. Lactobacillus can produce an array of flavors alongside its characteristic lactic tartness. A third family of haze-causing bacteria includes coliform, which produce vegetal off-flavors reminiscent of parsnips and old celery. Most such bacterial haze develops in the bottle after fermentation, and your only realistic options here are to choke it down, dump it out…or paint with it.
How to Fix Haze in Your Beer Recipe
You can try cold conditioning a yeasty beer for a few days to see if that helps settle out the haze. If cold conditioning doesn’t work, filtering out the yeast can solve the problem, too. Either way, fixing yeast-related haze is as simple as removing the problematic yeast cells.
Protein and polyphenol hazes are more complex, but they can be addressed in a number of ways. When you regularly use the same ingredients and brewing equipment, you might try tweaking your ingredient selection to include low-protein grains and adjuncts like corn, rice, or refined sugar. Protein rests and proper separation of wort from the hot and cold breaks prior to fermentation can also help reduce beer haze.
Hops also contribute polyphenols. Some brewers exclusively bitter with low-alpha-acid varieties to promote refined hop character. The downside to this practice is that a large amount of bulky hop material (up to four times as much as would be used of higher-alpha-acid varieties) is needed to achieve the right bitterness level, along with an increase in extracted polyphenols. A study referenced by John Palmer in “What is Beer Haze & Why Do We Care?” (Zymurgy, Sept./Oct. 2003) showed that 70 percent of malt polyphenols can survive hot and cold break, while only 20 percent of hop polyphenols do. The message here for reducing haze-causing polyphenols and proteins is to achieve a good hot break, perhaps aided by Irish moss, and use a wort chiller to get a good cold break.
If you are an all-grain brewer, your sparging method can also affect the haze in your beer. The higher the sparge temperature, the more polyphenols will end up in your wort. This can become a problem if you sparge above 180° F (82° C). A high mash pH (anything higher than about 8) can also extract large amounts of polyphenols during the last runnings as the buffering power of malt acids is rinsed away from the grain bed. Using a batch sparge can help prevent this problem, as can using fresh, healthy barley and being patient with your mash—don’t rush it.
How to Fix Haze with Filtration and Clarifiers
You can also use clarifiers and finings, otherwise known as seaweed, fish guts, and JELL-O®, to clear up the haze in your beer. Adding clarifiers to wort or beer chemically and electrostatically pulls haze out of the suspension and allows it to settle to the bottom. Irish moss, Whirlfloc™, and isinglass are among the most common such products used at the homebrewing level.
Some brewers prefer clarifiers and finings to filtration because they believe filtration might take away flavor from the beer. Although many brewers refuse to use chemical additives, an aversion to filtration is one reason why chemical approaches have developed. Others argue that filtration effectively removes haze without any appreciable effect on beer flavor. Check out the Clarifier Summary Chart below for a more complete list.
Clarifier Summary Table†
| Clarifier | Purpose | Amount | Comments |
|---|---|---|---|
| †Clarifier Summary Table can be found in “What is Beer Haze & Why Do We Care?” by John Palmer, Zymurgy September/October 2003 | |||
| Irish Moss | Protein Coagulant | 1 teaspoon per 5 gallons | A good clarifier for almost all worts, though not recommended for high adjunct worts. |
| Whirlfloc | Protein Coagulant | 1 tablet per 5 gallons | A good clarifier for almost all worts, though not recommended for high adjunct worts |
| Isinglass | Yeast Flocculent | 15-60 mg/L or 2 fl. oz. per 5 gallons | Most effective for settling yeast in finished beer. Will also settle some protein haze. |
| Gelatin | Yeast Flocculent | 60-90 mg/L | Only about one-half to one-thrid as effective as isinglass, also used in finished beer |
| Polyclar/PVPP | Polyphenol binder | 6-10 g/5 gallons | A non-aerated slurry should be mixed into finished beer before bottling and allowed to settle out. Should take a day at most. |
| Silica Gel | Protein binder | 6-10 g/5 gallons | A non-aerated slurry should be mixed into finished beer before bottling and allowed to settle out. Should take a day at most. |
When brewing a show beer to be judged in a homebrew competition or served at a wedding by those who are less understanding (or forgiving) than your fellow homebrewers, filtration could become not just desirable, but essential. If you choose to filter your beer, know that small-scale filtering systems are available, but they require that you keg and force carbonate your beer. Those who bottle condition are out of luck because when yeast is filtered out, beer can’t carbonate in a bottle.
The concept of filtration is easy to understand: it’s just the removal of solids from a liquid by passage across or through a porous medium. However, theory and practice are two different things. Filters can effectively remove particles of any size from beer, but as you move to ever-finer filters, the risk of stripping away flavor increases.
Filter fineness is expressed in terms of microns—one micron is one-millionth of a meter or 0.000039 inches. Yeast cells are relatively large, ranging from about three to 20 microns in size. By contrast, even the largest proteins and polyphenols are smaller than a yeast cell, and the smallest are more than 1,000 times smaller at 0.001 microns in size. Homebrewers typically use filters sized at 5, 1, and 0.5 microns, depending upon the level of clarity desired.
You can also filter out bacteria before they become a problem. Bacteria are relatively large, ranging from about 0.5 to 70 or 80 microns. Unfortunately, filtration is not an effective sanitation technique because you’re not necessarily filtering out all potential spoilage agents. It’s much better to practice better brewing techniques that involve thorough cleansing and sanitation.
7 steps to clearer beer
In summary, use the following seven steps to improve the clarity of your homebrew.
- Choose high-flocculating yeast.
- Brew with low-protein grains.
- Use Irish moss to achieve a good hot break.
- Cool wort quickly to achieve a good cold break.
- Add clarifiers or a fining agent to help clear beer haze.
- Cold condition your beer.
- Practice better brewing techniques, especially cleaning and sanitation.
Remember, we drink with our eyes first. By making the effort to reduce haze, you’ll improve your beer’s overall presentation and ensure that your memories of that great homebrew remain crystal clear well past the last sip.
Sources:
- “How Clear” by Ray Daniels, Zymurgy, 1997
- “What is Beer Haze & Why Do We Care?” by John Palmer, Zymurgy, September/October 2003
- Oxford Companion to Beer by Garrett Oliver, et al.
source: HBA