Section 5 – Appendices
Appendix C – Beer Clarity
What is Beer Haze and Why Do We Care?
Last month you planned and brewed what should be your best beer yet, and today is the first pour. Your recipe used: a new brand of malt extract/new specialty grain/wheat, and you added: dried hops/fruit/spices to the secondary fermenter to give it that extra flavor you were looking for. The guys at the homebrew shop had tried pulling your leg when you told them the recipe, suggesting that you add seaweed to the boil, and put fish guts and Jell-O in the fermenter. What a bunch of kidders, you didn’t believe a word of it!
And now you pour your best beer and, and ... it’s cloudy!? What happened?!
There are several possible causes of cloudy or hazy beer. Maybe it’s simply that your yeast has not flocculated (settled out) yet. You could try cold conditioning the beer for a few days to see if that helps. You might have a wild yeast or bacterial infection, or it could be haze due to unconverted/insoluble starch, or fruit pectin, or it could be a polyphenol/protein haze. How can you tell? What can you do about it? There is not much you can do about infections except dump the batch. Hazes due to starches represent a food source to many wild yeasts and bacteria and will cause flatulence as the starches are broken down in your gut. Fruit pectin haze can be combated by the use of pectic enzyme or by changing how you prepare your fruit for the fermenter. Finally, proteins and polyphenols from the malt and hops can combine to form both temporary and permanent hazes.
Everyone is used to seeing crystal-clear American light lager beer and assumes that this is how clear every beer should be. Wrong! In fact, the low-protein, high-adjunct beers of the United States are some of the clearest beers in the world, if not the clearest. The ingredients have a lot to do with it, but the other half of the equation is the filtering capability that large commercial breweries have available to them. Filtering systems for homebrewers are available but require that you keg the beer and force-carbonate, because the yeast is filtered out, too.
But other than aesthetics, why should you care about cloudy beer? You can’t taste haze ... or can you? Haze can often be an indicator of another problem, as in the case of bacterial infections. Bacteria often cause clouding of the beer and characteristic off-flavors. For instance, Pediococcus damnosus is a commonly feared brewery infection that generates high amounts of diacetyl. Lactobacillus bacteria can produce a variety of flavors—some of which are pleasant, as in lambic beers—in addition to the tartness of lactic acid. Other lacto strains will produce excessive amounts of diacetyl like the Pediococcus bacteria. A third type of haze-causing bacteria are coliforms, and these bacteria will often produce vegetal off-flavors, reminiscent of parsnips and old celery. These types of hazes will most likely develop in the bottle after fermentation, and the sudden appearance of haze can be an indicator that something has gone wrong.
But most haze in an otherwise good beer is caused by a combination of protein and polyphenols. Millions of dollars are spent annually researching and combating this type of haze. Why? Because the polyphenols that contribute to haze are part of a chemical equilibrium that contributes to oxidative staling reactions. You may be wondering just what a polyphenol is. You may have heard of them in terms of being an off-flavor in beer—sometimes having spicy, plastic, or medicinal flavors. No, actually those are phenols (hydroxyl group attached to an aromatic hydrocarbon) that have characteristic off-flavors. Polyphenols are polymers of phenol compounds. You may have heard that polyphenols are tannins. Actually it’s the other way around—tannins are a large type of polyphenol. And you have probably heard that oversparging and/or having the wrong mash pH will leach tannins into your wort. This is indeed true; tannins and other polyphenols can be extracted from the malt husks and from the papery hop cones. There will always be some level of polyphenols in the beer, but it’s like complaining about having sand in the desert. Unless there is a sandstorm, you just accept it and work around it. If you think of phenols as being like Lego blocks, you will get an idea of the size range, and how small polyphenols can link up to form large polyphenols and tannins. The most common manifestation of protein-polyphenol haze is “chill haze,” which is formed by small polyphenols cross-linking with protein. These complexes are insoluble when the beer is chilled but don’t have enough mass to settle out effectively. These chill haze complexes dissolve back into solution when the beer is warmed to room temperature.
Larger polyphenols form larger protein complexes and can settle out as hot and cold break, while the smaller polyphenols are carried over into the final beer. As mentioned earlier, these small polyphenols can grow by polymerization, especially in the presence of oxygen. If a beer with chill haze was poorly handled during bottling, the oxygen can cause the chill haze to become permanent haze.
It was interesting to note, while searching the abstracts in the professional brewing journals, that haze seems to have become a bigger problem in the past ten years. While this increase could simply be attributed to growth in the craftbrewing industry and a tighter focus on quality, a better explanation might be that there is also more awareness and control of oxidation in the wort production process. A reduction in wort oxidation will result in less polymerization of the smaller polyphenols, such that fewer polyphenols and tannins are precipitated in the break material during boiling and cooling. Thus, more polyphenols survive into the packaged beer, where they contribute to chill haze. In other words, a beer produced thirty years ago with little regard to hot side aeration may have been more prone to staling and had a shorter shelf life, but it was probably clearer than comparable beers today.
And now you pour your best beer and, and ... it’s cloudy!? What happened?!
There are several possible causes of cloudy or hazy beer. Maybe it’s simply that your yeast has not flocculated (settled out) yet. You could try cold conditioning the beer for a few days to see if that helps. You might have a wild yeast or bacterial infection, or it could be haze due to unconverted/insoluble starch, or fruit pectin, or it could be a polyphenol/protein haze. How can you tell? What can you do about it? There is not much you can do about infections except dump the batch. Hazes due to starches represent a food source to many wild yeasts and bacteria and will cause flatulence as the starches are broken down in your gut. Fruit pectin haze can be combated by the use of pectic enzyme or by changing how you prepare your fruit for the fermenter. Finally, proteins and polyphenols from the malt and hops can combine to form both temporary and permanent hazes.
Everyone is used to seeing crystal-clear American light lager beer and assumes that this is how clear every beer should be. Wrong! In fact, the low-protein, high-adjunct beers of the United States are some of the clearest beers in the world, if not the clearest. The ingredients have a lot to do with it, but the other half of the equation is the filtering capability that large commercial breweries have available to them. Filtering systems for homebrewers are available but require that you keg the beer and force-carbonate, because the yeast is filtered out, too.
But other than aesthetics, why should you care about cloudy beer? You can’t taste haze ... or can you? Haze can often be an indicator of another problem, as in the case of bacterial infections. Bacteria often cause clouding of the beer and characteristic off-flavors. For instance, Pediococcus damnosus is a commonly feared brewery infection that generates high amounts of diacetyl. Lactobacillus bacteria can produce a variety of flavors—some of which are pleasant, as in lambic beers—in addition to the tartness of lactic acid. Other lacto strains will produce excessive amounts of diacetyl like the Pediococcus bacteria. A third type of haze-causing bacteria are coliforms, and these bacteria will often produce vegetal off-flavors, reminiscent of parsnips and old celery. These types of hazes will most likely develop in the bottle after fermentation, and the sudden appearance of haze can be an indicator that something has gone wrong.
But most haze in an otherwise good beer is caused by a combination of protein and polyphenols. Millions of dollars are spent annually researching and combating this type of haze. Why? Because the polyphenols that contribute to haze are part of a chemical equilibrium that contributes to oxidative staling reactions. You may be wondering just what a polyphenol is. You may have heard of them in terms of being an off-flavor in beer—sometimes having spicy, plastic, or medicinal flavors. No, actually those are phenols (hydroxyl group attached to an aromatic hydrocarbon) that have characteristic off-flavors. Polyphenols are polymers of phenol compounds. You may have heard that polyphenols are tannins. Actually it’s the other way around—tannins are a large type of polyphenol. And you have probably heard that oversparging and/or having the wrong mash pH will leach tannins into your wort. This is indeed true; tannins and other polyphenols can be extracted from the malt husks and from the papery hop cones. There will always be some level of polyphenols in the beer, but it’s like complaining about having sand in the desert. Unless there is a sandstorm, you just accept it and work around it. If you think of phenols as being like Lego blocks, you will get an idea of the size range, and how small polyphenols can link up to form large polyphenols and tannins. The most common manifestation of protein-polyphenol haze is “chill haze,” which is formed by small polyphenols cross-linking with protein. These complexes are insoluble when the beer is chilled but don’t have enough mass to settle out effectively. These chill haze complexes dissolve back into solution when the beer is warmed to room temperature.
Larger polyphenols form larger protein complexes and can settle out as hot and cold break, while the smaller polyphenols are carried over into the final beer. As mentioned earlier, these small polyphenols can grow by polymerization, especially in the presence of oxygen. If a beer with chill haze was poorly handled during bottling, the oxygen can cause the chill haze to become permanent haze.
It was interesting to note, while searching the abstracts in the professional brewing journals, that haze seems to have become a bigger problem in the past ten years. While this increase could simply be attributed to growth in the craftbrewing industry and a tighter focus on quality, a better explanation might be that there is also more awareness and control of oxidation in the wort production process. A reduction in wort oxidation will result in less polymerization of the smaller polyphenols, such that fewer polyphenols and tannins are precipitated in the break material during boiling and cooling. Thus, more polyphenols survive into the packaged beer, where they contribute to chill haze. In other words, a beer produced thirty years ago with little regard to hot side aeration may have been more prone to staling and had a shorter shelf life, but it was probably clearer than comparable beers today.
Fixing Haze in the Recipe
To reduce the haze in your brewing, you can try to reduce the protein levels, reduce the polyphenols, or a bit of both. You can make the reductions by tweaking the recipe or by using clarifiers and finings. Each option has its pros and cons. To reduce proteins and/or polyphenol in the recipe, you can change from an all-malt recipe to one that uses a percentage of low-protein adjunct like corn, rice, or refined sugar, as exemplified by American light lager, Belgian-style tripel, and Belgian-style strong ale. Using wheat or wheat extract in a recipe to reduce polyphenols (wheat doesn’t have a husk) can be a double-edged sword. At low levels, 5 to 12% of fermentables, the high protein levels in wheat can cause extensive haze, but as the percentage of wheat increases to 40%, the total polyphenol levels are substantially decreased, and the beer is very clear.
Hops are another source of polyphenols in a recipe. A lot of brewers swear by the exclusive use of low-alpha aroma hops for bittering, justly claiming a more refined hop character in the beer. The downside to this is the greater proportion (up to four times) of hop cone material in the wort and the large amount of polyphenols that will be extracted from it during the boil. I brew an American wheat extract beer that tends to be hazy due to the wheat gluten. The last time I brewed it, I switched from using Nugget (12% alpha acids) as my bittering hop to using all Liberty (3.5% alpha acids). That batch had a superb hop character that was as rich as royalty, and a creamy head that needed a spoon to clean the glass, but it was hazier than previous batches. A study by McMurrough, et al. , showed that 70% of malt polyphenols can survive the hot and cold break, while only 20% of hop polyphenols do. The message here for reducing the polyphenols and proteins that cause haze 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 malts and the way you mash and sparge can affect your polyphenol levels, too. The Crisp Malting Group has developed a special barley strain and a resulting pale ale malt called Clarity that has extremely low polyphenol levels. Greg Beron of Culver City Brewing Supply in Los Angeles brewed a blonde ale using nine pounds of the malt plus some specialty grains without using other clarifiers, and the beer came out brilliantly clear. The local members of the Pacific Gravity brewing club gave the batch high marks. Your sparging method can also affect the total polyphenol levels. While the first runnings have been shown to generate the highest concentration of the small polyphenols, it is also known that the last runnings of a continuous sparge contain the highest proportion of tannin-type polyphenols extracted from the husks. This is due to the rise of the mash pH, as the buffering power of the malt acids is rinsed away from the grain bed. By using a batch sparge—where the final runnings typically don’t fall below 1.020, or a no-sparge technique—where there is no rinsing to change the mash pH, you can prevent excessive tannin extraction into your wort.
Hops are another source of polyphenols in a recipe. A lot of brewers swear by the exclusive use of low-alpha aroma hops for bittering, justly claiming a more refined hop character in the beer. The downside to this is the greater proportion (up to four times) of hop cone material in the wort and the large amount of polyphenols that will be extracted from it during the boil. I brew an American wheat extract beer that tends to be hazy due to the wheat gluten. The last time I brewed it, I switched from using Nugget (12% alpha acids) as my bittering hop to using all Liberty (3.5% alpha acids). That batch had a superb hop character that was as rich as royalty, and a creamy head that needed a spoon to clean the glass, but it was hazier than previous batches. A study by McMurrough, et al. , showed that 70% of malt polyphenols can survive the hot and cold break, while only 20% of hop polyphenols do. The message here for reducing the polyphenols and proteins that cause haze 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 malts and the way you mash and sparge can affect your polyphenol levels, too. The Crisp Malting Group has developed a special barley strain and a resulting pale ale malt called Clarity that has extremely low polyphenol levels. Greg Beron of Culver City Brewing Supply in Los Angeles brewed a blonde ale using nine pounds of the malt plus some specialty grains without using other clarifiers, and the beer came out brilliantly clear. The local members of the Pacific Gravity brewing club gave the batch high marks. Your sparging method can also affect the total polyphenol levels. While the first runnings have been shown to generate the highest concentration of the small polyphenols, it is also known that the last runnings of a continuous sparge contain the highest proportion of tannin-type polyphenols extracted from the husks. This is due to the rise of the mash pH, as the buffering power of the malt acids is rinsed away from the grain bed. By using a batch sparge—where the final runnings typically don’t fall below 1.020, or a no-sparge technique—where there is no rinsing to change the mash pH, you can prevent excessive tannin extraction into your wort.
Fixing Haze with Clarifiers and Finings
Now we come to the seaweed, fish guts, and Jell-O. You can add clarifiers to your wort and beer that will chemically and electrostatically pull haze formers out of solution and allow them to settle to the bottom. Irish moss and isinglass are the most common clarifiers used by homebrewers.
Irish Moss
Irish moss is a type of red seaweed called carrageen that preferentially attracts large proteins. Irish moss is the only clarifier that you add to your boil. All other clarifiers are added after fermentation. Irish moss is added during the last 20 minutes of the boil, where it greatly enhances the clumping and precipitation of the hot break proteins that would otherwise contribute to haze and staling reactions. In the past, it was generally accepted that the proteins that caused haze were different from the proteins that were responsible for head retention. However, more recent studies show that the proteins are similar enough that any attempt to eliminate haze-forming proteins via enzymes or non-specific protein-absorbing additives like bentonite will also affect the head retention and body of the beer. What this means to you is that any suggestions you may receive about adding a protein rest to your mash schedule or enzyme clarifiers to your wort are probably not good ideas. In addition, misuse of the right clarifiers can also be trouble. If too much Irish moss is used in the boil, the smaller proteins responsible for head retention can be affected and could reduce the free amino nitrogen (FAN) that the yeast need for nutrition. For this reason, it is not recommended for use with malt extract/adjunct worts. It is commonly available as dry flakes that are rehydrated before use. A typical dose is 1 teaspoon of flakes for 5 gallons of boil volume, or one-eighth gram per liter of boil. Another form of Irish moss is a product called Whirlfloc from Australia. It is a large tablet that you simply drop into your wort. Each tablet is good for a 5-gallon batch. People have reported excellent results using Whirlfloc.
Isinglass
The other popular fining agent is isinglass, commonly used in English cask ales. Composed almost entirely of the protein collagen, it is obtained by cleaning and drying the swim bladders of the sturgeon, cod, hake, and other fishes. It is an excellent clarifier for yeast. While it is able to bind and settle some of the larger proteins, it is not very effective for reducing chill haze. Isinglass is sold as dehydrated powder to be used at 30 to 60 milligrams/liter dosage, but it is most commonly available for homebrewers as a ready-to-use liquid. To use it, add it to the fermenter after fermentation has finished, or to the bottling bucket when you add your priming sugar solution, but do not attempt to heat it up, because it is easily denatured. Two ounces of liquid will treat 5 gallons of beer.
(Seriously, you have to wonder whose idea this was. “Igor, go get me some fish guts to add to the beer. What! Nothing fresh? Well, just scrape some of that dried stuff off the cutting board there. . . .”)
(Seriously, you have to wonder whose idea this was. “Igor, go get me some fish guts to add to the beer. What! Nothing fresh? Well, just scrape some of that dried stuff off the cutting board there. . . .”)
Gelatin
Gelatin is a by-product of the collagen extraction process from cow hooves and pigskin. It is not as effective as collagen at settling the yeast mass, needing about three times as much to do the same job. But it is much less expensive. Gelatin is mixed and combined with the beer in the same way as isinglass, but at levels of 60 to 90 milligrams/liter.
PVPP/Polyclar(tm)
Polyvinylpolypyrrolidone, also known as povidone, is a micronized white powder, with a high surface-area-to-volume ratio that readily absorbs polyphenols, including tannins. The necessary contact time is only a few hours. Commercially, it is the most popular clarifier and stabilizer. About 6 to 10 grams per 20 liters/5 gallons is added after fermentation, prior to bottling. It is commonly combined with cooled boiled water to form a slurry that is gently added to the fermenter. The slurry needs to be mixed thoroughly with the beer and allowed to settle out (less than one day). Then the beer should be racked off the sediment and bottled or kegged. This material is not approved by the Food and Drug Administration for ingestion. Commercial breweries remove it by filtration.
Silica Gel
Silica hydrogels and xerogels are the other half of the one-two punch that commercial brewers use to control haze and improve shelf life. Where PVPP works to bind polyphenols, silica gel binds to proteins. In fact, it binds preferentially to haze-active proteins, because chemically it reacts with the same sites on the proteins that the polyphenols do. Silica gel is used at the same 6 to 10 grams per 20 liters/5 gallons rate and with the same procedure as Polyclar®. Silica gel and PVPP work synergistically to reduce haze more than each would alone. A combined product called Polyclar Plus is available to commercial breweries; I don’t know if it has been packaged for a homebrewing scale. This material is not approved by the FDA for ingestion. Commercial breweries remove it by filtration. Allowing the material to settle and carefully racking away from the sediment should be sufficient.
Summary
Beer haze can have many possible causes, but a hazy beer that tastes good is probably suffering protein/polyphenol haze. Haze is usually treatable by the use of different ingredients, including malt and hop varieties, as well as by additives like clarifiers and finings. Hopefully, this discussion has helped you understand how these hazes form and how to best address the cause and solution in your own brewery.
Author’s Note: This work was originally published as a feature article in Zymurgy 26, no. 5 (2003).
Table 34 - Clarifier Summary
