Many brewers find that one of the issues they face is the lack of wort and beer clarity. While haze and cloudiness do not necessarily impact the flavor of the beer, it does contribute to long term stability issues, as well being aesthetically displeasing.One simple way to help create a clearer beer is to create a clear wort. That sounds intuitive in a way, but it’s easier said than done.
Several things contribute to haze, including yeast in suspension, but as a general rule of thumb “Clear wort makes clear beer” . If the wort is clear going into the fermenter, the things that may impact clarity later are easier to identify. Things like yeast haze and hops haze (from dryhopping) are easy to pick out in a finished beer. We will discuss chill haze, and how a clear wort can help or prevent it altogether.
First, wort of course comes from grain and the magic of the enzymatic activity of the mash takes the starch from the malted grain and turns it into fermentable sugar. A good mash pH helps with all of this. There are other things in the wort besides sugar, including proteins, tannins, polyphenols, and so on. Some grains (notably wheat) have more protein than others. It is during the boil that the rolling action of the boil causes foam to rise up- and threaten to boil over! The wort will continue to foam, until the protein starts to clump together and then get heavy enough to fall back into the wort. This is called the ‘hot break”. Once the hot break occurs, the wort will look a bit like egg drop soup, and have fine particles of protein throughout. After that happens, the wort will not threaten to boil over again, so you know that you’ve had your hot break.
A small sample of the wort after the hot break:
A good hot break will go a long way to the creation of clear wort. It’s not just proteins that are creating the hot break reaction- in addition to the proteins, other polypeptides present in the wort will combine with tannins or polyphenols and become part of the hot break, due to their electrical charges. Other reactions are happening during the boil also- DMS precursors are driven off, isomerization of hops oils, color development due to maillard reactions, concentration of the wort, and the pH of the wort will drop, primarly due to the precipitation of calcium phosphate. Calcium in the brewing water reacts with phosphates from the malt, and this reaction will lower the wort pH.
The next item to discuss for wort clarity is then the ‘cold break’. Cold break happens when the finished wort cools. Cold break is again mostly proteins, but another group of proteins that need to precipitate out of the wort to form a clear wort. The lack of a cold break is generally not a big issue in the flavor of the finished beer- instead it is mostly an aesthetic issue but it can affect long term stability of the beer. For most homebrewers, that isn’t an issue either, as we rarely have to worry about that, unlike commercial breweries. Still, from an aesthetics standpoint many brewers would prefer to have clear beer to serve to friends and guests.
Quick chilling helps form a good cold break, and kettle finings such as whirlfloc or Irish moss can be helpful in that reaction.
Here is a hydrometer sample of wort straight from the kettle, with both the hot break and cold break suspended in the cooled wort:
That isn’t very appealing! But within 5 minutes or so, gravity does its magic and the hot break and the cold break start to fall out:
Within 15 minutes, the hydrometer sample is perfectly clear, with the break material on the bottom:
By the time the wort is chilled completely, the wort is completely clear. When this beer is finished, if the beer is cloudy then it’s most likely a yeast haze, or if the beer is dryhopped there could be a hops haze. Some yeast strains are non-flocculant and will not clear well without filtering, while other yeast strains (such as the English strains) will clear the beer well when fermentation is finished. Hops haze is generally an oil slick-type of haze, and does not create a murky beer. Some ingredients, like wheat, can create a haze due to the large amount of protein in it. There are some advantages to a beer with wheat as an ingredient, such as great foam and head retention.
If a beer is cloudy after fermentation, there are some techniques that can clear the beer even without filtering. Cold crashing, adding finings like gelatin, and time can all work to create a clear finished beer. If you start with a clear wort, finishing the beer so that it is clear is much easier, often without any post-fermentation action by the brewer. While a clear wort doesn’t always guarantee a clear beer, it does tend to happen more easily. It’s worth pursuing a good hot break, and a good break, as well as maintaining a proper mash pH to enhance the odds of making a clear beer with minimal effort.