Beer: Hazed and Confused

First off, I must admit that I am far too proud of myself for coming up with that title, an homage to the classic nothing-actually-happens film Dazed and Confused .  I’ll be talking about what causes beer haze, what you can do about it, and crow-bar in my own opinion on whether or not you should even bother with it.  Because, why else do you write your own blog than to crowbar in your own opinion whenever possible?

Haze in beer is caused by particles scattering light, causing it to bounce around instead of passing right though.  The size of the particles is important: too small, and they aren’t big enough to “interact” with light; too big, and they will likely settle out quickly and not be a problem.

beer haze

A perfect example of glucan “starch” haze from rye malt.

Chill Haze

Cause: Chill haze is the most common form of haze.  It is so named because it will go away as the beer warms, and come back as it is cooled.  All but the most meticulously prepared of beers will haze at some point before it freezes; less stable beers will haze at warmer temperatures.  It is caused by high molecular weight proteins (larger than those responsible for head and body) and polyphenols (tannins) forming weak, temperature sensitive “hydrogen” bonds.  Alone, they are usually not large enough to scatter light, but become large enough as they bond together.  As the temperature rises, the molecules move around faster and the weak bonds are torn apart.  Beers with higher levels of these compounds will haze at higher temperatures.

Solution One, Fining Agents:  There are various fining agents, some which aim to get rid of proteins, and others which go after polyphenols.  Irish moss can be used during the last 10-15 minutes of the boil to clump proteins and form a better hot break.  Whirlfloc is a prepared form of the active ingredient in Irish moss (carrageen).  PVPP (polyvinylpyrrolidone, trade name Polyclar), used after fermentation, is very effective at attracting and pulling polyphenols out of the beer.  Silica gel, often used in conjunction with PVPP commercially, binds selectively to larger haze-form proteins, leaving more of the smaller head and body proteins alone.

See How to Brew, Appendix C, for recommended dosage rates; pre-fermentation fining agents are not recommended for extract or high adjunct brews, as they also reduce FAN (free amino nitrogen, a yeast nutrient), which is already low in these worts.

Solution Two, Filtration: Filtration down to the 3-5 µm level will not significantly alter the beer (ie hop character, body, and head retention), and has been shown to reduce haze better than fining agents.  Fining and filtration can be combined, though this likely will not reduce initial haze beyond filtering alone.  Filtering below 3 µm will start to have flavor, body, and other impacts.

Solution Three, Ice Stabilization:  Unless you are the Labatt brewing company, you will likely be unable to use this method without significantly altering the beer.  It involves partially freezing the beer and throwing away the ice crystals.  This is the traditional method of making high-strength bock beers; haze-forming and harshly flavored compounds are removed in the water ice, yielding a more clear, mellow beer, better even than filtering.  Labatt has patented an industrial process which removes only 2% of the water as ice, thus avoiding it being considered distillation by the (North American) authorities.

Worth it?  If you’re not worried about long shelf life and long term stability (most home brewers need not be), this is just a cosmetic issue.  If you’re entering a competition, appearance is usually worth three points.  I take the easiest step possible (using Irish moss in the kettle) to help avoid haze, and otherwise say “meh.”  Frankly I don’t care much about haze in general, but I find Irish moss helps clump everything up and makes transferring the wort to the fermentor a little easier.

Hop Haze

Cause: This is not truly a separate type of haze.  In beers using a large quantity of hops, this haze is often evident; dry hopped beers are famous for this type of haze.  Many think it is from hop oils in solution, but it is simply additional polyphenol compounds from the leafy bits of the hop matter.

Solution: Using pellet hops instead of whole hop cones is a start, as there is less leafy material for a given amount of hop oil.  Otherwise, following the procedures above will help, especially those focused on reducing polyphenols.

Worth it? Meh.  Again, this is mainly a cosmetic issue.  Even better, minor haze is considered acceptable in style guidelines for highly hopped beers like west coast style American IPAs.

Oxidation Haze

Cause: All beer will eventually fall victim to oxidation haze.  Free oxygen (air in the bottle neck or keg), or oxygen bound to other compounds in the beer (many malt compounds are oxidized while brewing, for example), will cause the same proteins and polyphenols responsible for chill haze to bind permanently.  Higher temperatures, mechanical abuse (ie shaking during shipping), and light can all speed the process.  Beers brewed with water having higher than normal metal levels are especially prone to oxidative haze.

Solution: Try to minimize oxidation during the brewing process, and use the same techniques as for reducing chill haze.  Filtering is again more effecting than fining.  However, a combination of fining and filtration will slow the process of oxidation haze further than either alone, even though it will not improve initial clarity beyond just filtering.  A combination of filtering and ice stabilization is most effective at preventing the onset of haze.

Worth it? Yes, but don’t go crazy.  This is really more of a concern of commercial brewers who need to maintain shelf stability of their product through heat and shaking during distribution, and long periods sitting at a store.  The big guys are down to parts per billion of free oxygen at bottling, lower even than you can get water by boiling it (which is a few parts per million).  As a home brewer, just avoid too much abuse of the wort and finished beer.  Bottle conditioning can help to scavenge some free oxygen out of the beer after the bottling process.

Yeast Haze

Cause: If you’ve ever brewed a beer with a yeast which did not include in the description “forms compact sediment” and “highly flocculant,” you’ve probably seen yeast haze.

Solution: Yeast haze can correct itself with time, depending on the yeast, as it will continue to flocculate.  Generally, leaving the beer in the fermentor a bit longer before bottling or kegging will help.  However, some yeast strands are very stubborn.  Cold conditioning as close to freezing without freezing is probably the best way to force flocculation, but gelatin or Isinglass can also be used post-fermentation. If you require something more immediate, you’ll need to resort to filtering down to the 3-5 µm level.

Ensure your water has enough calcium and the yeast are otherwise healthy, as both will help flocculation.  Strains can mutate if stressed or harvested incorrectly to become near completely unable to flocculate on their own.

If you plan on bottle conditioning, you should add back yeast after fining or filtering.  American, English, and German beers of average carbonation are usually packaged with a target of 100,000 cells/mL.  Belgian ales of high carbonation can be as high as 1-3 million cells/mL.  This means for a typical 5 gal/ 18.9 L batch, you will need to supply 2 billion or 20-60 billion cells, respectively.  Both White Labs and Wyeast claim 100 billions cells per package; White Labs has 2.9 billion cells/mL and Wyeast has about 800 million cells/mL.  Dry yeast typically has about 20 billion cells per gram.

Worth it? Some beers styles, like hefeweizens, require this yeast haze.  Other beer styles should be free of extraneous yeast, as too much can lead to autolysis-related off flavors (meaty, soapy, plastic), and give spoilage organisms something to feed on.  “Yeast bite” can also occur, a harsh off-flavor from the yeast themselves.  If you’re only planning on enjoying the beer at home and not transporting it, the standard two weeks at room temperature in the fermentor should let enough yeast settle out and leave way more than enough for bottle conditioning.    If you are planning on sending the beer off to competition, it is best to fine or filter before bottling.

Starch Haze

Cause: This is a permanent haze, and is caused by mashing errors.  The most likely cause is incomplete conversion of long-chain starches into fermentable sugars.  However, a malt with high levels of β-glucan, such as wheat, rye, or a low quality barley, can also be indicated.  If you made a fruit beer, it could also be a pectin haze.

Solution: If you are using good quality barley malt, review your mash procedures.  Ensure your mash temperature is in a good range (140-162F/ 60-72C), the mash is given enough time (up to an hour or more at low temperatures), and that you have enough base malt to provide the necessary enzymes for conversion.  If you are using higher levels of wheat and rye,  poor quality malt, or un-malted grains, you may wish to employ a protein rest at 113-131F/ 45-55C.  This will activate β-glucanase enzymes and break down these long haze-forming chains.  For pectin issues, add pectinase enzyme to your beer in the fermentor or prepare your fruit addition differently.

Worth it?  If your problem is incomplete conversion of starches, you should definitely fix this issue, as it is a fundamental brewing flaw (and the starches make great food for gut bacteria which results in terrible gas).  If the problem is higher levels of β-glucans and you plan to drink the beer quickly, fix at your discretion.  Ultimately it can lead to stability issues and hide other flaws, but its otherwise cosmetic.

Biological Haze

Cause: Wild yeast or bacteria can sometimes form thin ropey strips in beer, causing haze.  However, this generally only happens with extremely high levels of contaminate microbes; effects on taste will occur well before this.

Solution: If a wild organism has reached these levels, you probably have a serious flaw in your cleaning/ sanitation routine.  Ensure everything is clean, and anything that touches the beer on the cold side is sanitized.  Replace hoses and gaskets first, followed by anything else plastic if problems continue.  And keep your cat from falling in your bucket of wort, and make sure your dog isn’t drinking any.

Worth it? Yes!  Your brew is likely undrinkable if wild organisms are causing visible problems, and you can have serious bottle-bomb issues.

 [Most of the information in this post comes from Principles of Brewing Science, 2nd edition, Dr. George Fix and How to Brew, 3rd edition, John Palmer.]

– Dennis,
Life, Fermented


About Dennis
Home brewer, home chef, garage tinkerer. Author of Life Fermented blog.

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