It is well known that the sterilization method used in beer brewing has an important influence on beer fermentation. At present, there are several commonly used sterilization methods:
Microorganisms have suitable growth temperatures, which can cause death when they exceed their maximum growth temperature range. Therefore, heating has become one of the most widely used and effective methods in sterilization and disinfection. All hose and fixing tubes connected to the material must be steam sterilized by 30 min before use.
Advantages: Steam has broad spectrum, easy to obtain, non-toxic, non-corrosive, and good permeability.
Disadvantages: Steam is easy to form thin films, slow warming, energy consumption. Beer can pass pasteurization for 20 minutes at 60 °C. However, due to the long heating time, it has a certain influence on the flavor, nutrient composition and colloidal stability of the product.
II. Ultraviolet sterilization
The bactericidal effect of ultraviolet light on water is very effective. Its activity depends on pH and temperature and is widely used in the preparation system of aseptic water.
Advantages: No residual taste and gas, low toxicity.
Disadvantages: Poor permeability, sterilization effect depends on the turbidity of water, and there is no residual activity, easy to cause bacteria to grow again.
III. Gaodianya sterilization
The Japanese company Kirin Brewery has developed a new method of killing only the contaminated bacteria in beer by adding Gaodianya to the beer.
Advantages: Compared with the heat killing method, this method consumes less energy and the quality of beer will not be affected.
Strong bases[commonly used fire bases(NaOH)] can hydrolyze proteins and nucleic acids, destroying the enzyme system and cell structure of microorganisms and causing bacterial death. During the production process, thin plate coolers and wheat juice pipelines must be recycled with hot alkali water every day; At the same time, the used breeding tanks and fermentation tanks must be washed in a NaOH solution with a temperature of 80-85 °C and a mass score of about 10 %.
Advantages: In addition to the sterilization of alkaloids, they can also go to oil. At the same time, the stronger the alkalinity, the better the bactericidal effect.
The bactericidal effect of formaldehyde is that it has a reducing effect, can inhibit bacteria or sterilize, and can bind to the amino group of proteins to denature the protein, thus destroying the cytoplasm of the bacteria. After washing the clean breeding tanks and fermentation tanks with NaOH solution, it should also be sealed with a formaldehyde solution with a mass score of 2 %, and then washed with water for backup.
VI. Oxidation and sterilization
Oxidizing agents can release oxygen or release oxygen from other compounds. The oxidant acts on the amino group, hydroxyl group, or other chemical gene in the protein structure of the microorganism, causing its metabolic dysfunction and death. After each use of the yeast additive, it must be washed with water and soaked with hydrogen peroxide(H2O2) or bleach solution. Before next use, it must be washed with water.
VII. Tunnel-type hot water sprinkler system
At present, beer sterilization has emerged a tunnel type hot water spray system. The system is mainly composed of hot water supply, sprinkler and beer conveyor, and is generally divided into several different temperature sections along the length of the tunnel. After the raw beer is bottled and sealed, it enters the preheating section of the sterilizer, passes through the sterilization section and the cooling section one by one with the conveyor belt, and then leaves the sterilizer from the other end.