A chill haze sounds like the feeling you get when you drink a cold craft beer on a hot summer day. But it's actually a relatively common phenomenon that happens when beer is chilled. Chill haze doesn't typically impact the taste of beer, but it does give it a cloudy look that may not appeal to consumers.
There are several ways to combat chill haze, including adding enzymes to your wort.
What is Chill Haze?
A chill haze is what happens when colloidal particles appear in beer as it's cooled, usually to about 0°C. These particles make the beer look cloudy or hazy, and they disappear once it is warmed to 20°C or higher. However, with time, chill haze can develop into permanent haze, and it is irreversible.
How Does Chill Haze Occur?
Chill haze occurs due to proteins and flavonoids (a.k.a. polyphenols) forming a bond when the beer is chilled. These particles are large and able to reflect light, which makes them visible in the beer. The majority — anywhere from 40 to 75 percent —of haze material is comprised of proteins while polyphenols make up about 17 percent. Even though proteins make up most of the haze, polyphenols may be what actually makes the haze happen.
As flavonoids are oxidized, they form tannoids. Tannoids bond with proteins and are so large they no longer disappear when the beer is warmed, which leads to permanent haze.
The proteins in beer aren't inherently problematic, though. Some proteins are responsible for beer's rich foaminess. The proteins that cause haze formation are proline-rich proteins, which bond more readily with polyphenols.
What Influences Haze Development?
There are several factors that can impact whether a chill or permanent haze occurs in your craft beer. The concentration of polyphenols is an important factor. The amount of movement, light, oxygen and heat your beer is exposed to will also impact whether a haze will occur. Particulates like carbohydrates and the presence of heavy metals such as iron can also influence haze development.
How Do You Prevent Chill Haze Formation?
One approach to preventing chill haze formation is to remove the proteins and polyphenols that cause haze development. You can do this by introducing enzymes into the wort, which can break down proteins and prevent chill haze from occurring.
Removing the materials that cause haze formation has other benefits as well. Eliminating the proteins that cause haze formation can increase shelf life by three to five months. Removing the polyphenols associated with haze formation can increase shelf life by six to nine months.
You can also help prevent chill haze by choosing the right raw materials. Low-polyphenol-content malts exist, but you should pick them carefully as some compromise on flavor. Hop leaves contain more polyphenols than hop extracts.
You can also adjust your ratios while brewing and use more rice or corn. Avoid weak worts. When it comes to fermentation, add yeast immediately to minimize oxidation.
Your mashing regimen can also impact whether a haze is formed. Use the correct mash temperature to minimize the potential for haze formation.
In terms of your overall process, use a coarse grind of malt. Boil your beer at a rolling boil for at least 60 minutes and keep the beer cold throughout filtration. Sometimes beer can warm during filtration, but it should be kept cold to minimize the potential for haze formation. If you chill the beer to a low temperature (-1°C) before filtration, this can force haze formation, which you can then filter out.
If you don't want to deal with any additives, cold crashing can be used to achieve haze-free beer. Cold crashing refers to storing beer at a near-freezing temperature for one to eight weeks. This causes any potential haze to form and then settle to the bottom of the container. This technique takes a lot of storage space and patience. If you aren't willing to wait, additives can be used to help prevent chill haze.
What Can I Add to Prevent Chill Haze?
In addition to enzymes, there are other processing aids you can add to beer to help prevent chill haze. Each option has its pros and cons in terms of its influence on your beer's foaming ability and shelf life. Different methods are sometimes used in combination.
One technique is precipitation, which is done by using kettle finings, which are usually made from Irish moss, a seaweed that grows along the Atlantic coast. Irish moss contains carrageenan, which has a negative charge. This causes it to bond with proteins that have a positive charge. Irish moss is added to the boiling wort and forms large clumps when cooled, called a cold break, that is then removed. This improves filterability and can be combined with other techniques — but the effect is limited.
Another precipitation technique is adding tannic acid. This forces haze formation that can then be filtered out. It creates a sediment that can be difficult to filter, though it does improve shelf life.
Adding silica gel is an adsorption technique. Silica gel removes the proteins that react with polyphenols, helping prevent haze. It's usually added before filtration and then removed during the filtration process. If you're just using silica gel as a stabilizer, the dose can be relatively high, and it can impact foam retention.
Another adsorption technique is using PVPP, which is a polymer that bonds with polyphenols. There are two methods for adding PVPP. One is adding PVPP one time to unfiltered beer, which is then filtered. The other is regenerable PVPP, where PVPP is added to filtered beer and then filtered out with a special filter. The PVPP can be washed out and reused, which can save money.
Some brewers combine silica gel and PVPP, thereby reducing both proteins and polyphenols. This process is more expensive but doesn't impact foam retention, and both are removed by filtration, so nothing is carried over to the finished product.
What About Suspended Yeast?
Another factor that can contribute to haze is suspended yeast. Suspended yeast is typically dealt with after fermentation by using cask finings. These cause yeast cells to drop and make your beer clearer. Filtering and centrifuging can help, of course, but there are other cask finings you can use as well.
Two common cask finings are gelatin and isinglass. Neither of these are vegetarian-friendly. Gelatin will pull yeast down to the bottom of the cask so you get a clearer brew. Isinglass also bonds with yeast and forms a solution made of collagen, which settles to the bottom of the cask.
Author Bio: Stacey Gavin is a wellness expert who studies the use of enzymes to improve health, wellbeing, and adult beverages! These days when she isn't researching she can be found on the beach listening to Cardi B and enjoying everything the Lowcountry has to offer.