The clarity of a beer's body is part of a beer's style. The clarity is usually ranked using word descriptions, with brilliant being the most translucent, and cloudy being the most opaque.
Cloudiness occurs from suspended solid particles in beer. The scientific term for these particles suspended in a liquid is colloid. The scientific term for the cloudiness effect is turbidity.
The particles may be proteins from the cereal grains used in the beer recipe. They are high-mass and are more noticeable at lower beer temperatures. The typical term for the effect is Chill Haze. This term sounds bad, but these proteins are part of the beer's flavor/aroma, and are not a flaw, just cosmetic. But for some brewers' aesthetic preferences, brewing techniques can be used to reduce Chill Haze. Proteins are chains of amino acids.
The particles may also be yeast. Some beer styles are bottle conditioned or cask conditioned. This means the yeast is not filtered out after fermentation (which requires a fine filter), and the beer is not pasteurized. The yeast continue to live in and refine the beer until consumed, but may settle (flocculate) over time becoming a gray opaque sediment in the bottom of the serving container. Most yeast from a bottle or cask conditioned beer should be left at the bottom (not consumed), as they would taste muddy. Unfiltered wheat beers are the exception, and the yeast sediment should be stirred up and poured with the beer when serving.
The particles may possibly be starch. In most beer styles, starches are converted into sugars, via mashing cereal grains, because sugar is required for fermentation. However, there are styles that intentionally leave starch in the beer recipe. Suspended starch creates a silver sheen turbidity, which is where the beer style name Witbier (white beer) originated. The effect may be called Starch Haze. Starches are carbohydrates that are longer chains than sugars.
Beers are naturally cloudy. High clarity is achieved by numerous mashing and filtering techniques during the brewing process.
Filtering Step for Clarity
A brewer can increase the clarity of a beer by using a finer filter size during the filtering step of the cellaring stage of the brewing process. The filter size is measured in microns. Filters are approximately 10, 5, 1, and 0.5 microns.
Boiling Step for Clarity
After mashing, the extended boil step can be used to achieve a hot break, which coagulates some of the cereal grain proteins that would otherwise produce cloudiness in a finished beer. The hot break reduces beer cloudiness.
Cooling Step for Clarity
After the extended boil, the cooling step can be used to achieve a cold break, which causes dissolved solids (from cereal grains, hops, herbs, and spices) to settle out before they transform into more stable versions. The cold break reduces beer cloudiness.
Conditioning Step for Clarity
Some beers are bottle conditioned or cask conditioned. This conditioning technique can increase beer cloudiness, depending on the yeast strain's flocculation.
Additive Ingredients for Clarity