Turbidity Problems in Beer Fermentation

Cloudy beer is a beer that contains a specific amount of live yeast in the finished product and has a turbidity unit of 2.0 to 5.0 EBC. Beer design requires a specific turbidity (except wheat beer, turbidity IPA, and some dark beers). Unless there are special circumstances, beer is still distinguished by color and transparency. Below we will introduce the biological turbidity and abiotic turbidity of beer.

Biological Turbidity: The fermentation process contaminates various other microorganisms, leading to lethal increases in beer temperatures.The Pu value that completes beer sterilization is reduced, the water temperature level of the sanitary device is reduced or the water spray has dead ends, and yeast and contaminating microorganisms cannot be eliminated. For biological turbidity, strict procedural hygiene is completely preventable.

Abiotic turbidity：the compounds responsible for abiotic turbidity in beer are primarily healthy proteins, peptides, polyphenols, polysaccharides, and hop resins. The main types of turbidity are protein polyphenol turbidity, dextrin turbidity, polysaccharide and protein-polyphenol composite precipitation, inorganic precipitation, and hop resin turbidity.

The healthy proteins in beer mainly come from malt, and the healthy proteins that cause the turbidity of beer include gliadin and β-globulin; the polyphenols in beer come from bark and hops, and the polyphenols that cause the turbidity of beer generally come from yellow Alkyl hydroxyl. Healthy proteins and polyphenols are often clouded by the oxidation and polymerization of large amounts of steel. According to its development, it can be divided into the following situations:

True healthy protein turbidity (hygienic turbidity): Because the pH of beer is similar to the isoelectric factor of healthy protein, and the healthy protein content is high, the healthy protein water film in beer will be affected throughout the sanitation and home heating process. damaged.

Cold turbidity: Beer stored at reduced temperature (0°C) will definitely lose its luster and cloudiness, but when the beer is heated to 20°C or higher, its turbidity will definitely decrease or disappear, which is called cold turbidity or Relatively constant turbidity. Because wort and beer contain additional beta-globulin and delta-gliadin, they hydrogen bond with water at ideal temperature levels and are water soluble. Weak hydrogen bonds are broken when beer is heated above 20°C. The shine of the beer will fade and the healthy protein will combine with the water to form a liquid.

Permanent turbidity (oxidative turbidity): After the beer is stored for a certain period of time, the polyphenols in the beer, anthocyanins and healthy proteins, are oxidized and polymerized to form oxidized polyphenols and also polymerize healthy proteins. The two polymers covalently bond to create larger fragments of healthy protein-polyphenolic polymers that rise from the beer at an accelerated rate, appearing cloudy at first, then stop and gradually pick the container's all-time low, forming a thin, loose layer of Fragments, the wine body gradually returns to clear and transparent, and this turbidity is irreversible.