There are the following ways to remove bacteria and sterilize water from beer production: (1) Sand rod (sand filter rod) filtration is carried out by using sand filter rod filter equipment to remove microorganisms and some organic impurities in water, and to dissolve salt in water. Molecular impurities do not play a role in filtration. (2) chlorination and sterilization are often replaced by bleach powder because of the difficulty of liquid chlorine. However, saccharification water, yeast washing, culture water, dilution beer water, beer filter water can not be used to remove bacteria. (3) Ozone sterilization requires special ozone sterilization equipment. After filtration, the amount of ozone added 0.1 ~ 1g/m3 can achieve satisfactory bactericidal effect. (4) UV sterilization requires special ultraviolet sterilization equipment. Ultraviolet radiation with wavelength in 200~300nm has bactericidal ability, and ultraviolet sterilization ability is the strongest when wavelength is in 260nm. It can be used for sterilization of yeast washing water and beer dilution water.
As we all know, what kind of sterilization method is adopted in beer brewing has an important influence on beer fermentation. At present, there are the following commonly used sterilization methods, thermal sterilization microorganisms have their suitable growth temperature, beyond its maximum growth temperature range, will cause death. Therefore, heating has become one of the most widely used and effective methods in sterilization and disinfection. All hose and fixing pipes of connecting materials need to be sterilized by 30min steam before they are used. Advantages: steam has broad spectrum, easy to obtain, non-toxic, non-corrosive, and has good permeability. Disadvantages: steam easy to form thin films, slow heating, energy consumption. Beer can be sterilized by Pasteur and lasts 20 minutes at 60 ℃. However, due to the long heating time, it has a certain effect on the flavor, nutritional composition and colloid stability of the product. Second, the bactericidal effect of ultraviolet radiation on water is very effective, and its activity depends on pH, temperature, and is widely used in the preparation system of aseptic water. Advantages: no residual taste and gas, low toxicity. Disadvantages: poor permeability, bactericidal effect depends on the turbidity of water, and no residual activity, easy to lead to bacterial growth again. Third, high voltage sterilization Japan Kirin Beer Company has developed a new method of killing only contaminated bacteria in beer by adding instantaneous high voltage to beer. Advantages: compared with thermal sterilization, this method consumes less energy and the quality of beer will not be affected. Fourth, alkali bactericidal strong alkali [commonly used fire alkali (NaOH)] can hydrolyze protein and nucleic acid, destroy the enzyme system and cell structure of microorganisms, and cause bacterial death. In the production process, the thin plate cooler and wort pipeline should be sterilized by hot alkali water every day, and the fermenter should be washed with NaOH solution with temperature 80 ℃ and mass fraction of about 10%. Advantages: alkali not only has bactericidal effect, but also can remove oil pollution. At the same time, the stronger the alkalinity, the better the bactericidal effect. Fifth, the bactericidal effect of formaldehyde is that it has reductive effect, can inhibit bacteria or sterilize, and can combine with the amino group of protein to denaturalize the protein, which destroys the cytoplasm of bacteria. Rinse the breeding tank and fermenter with NaOH solution, rinse with clean water, seal with 2% formaldehyde solution for 2 h, rinse with clean water and set aside. Sixth, oxidation sterilizing oxidant can release free oxygen or other compounds. Oxidant acts on amino, hydroxyl or other chemical genes in microbial protein structure, resulting in metabolic dysfunction and death. After each use of yeast additive, rinse with clean water and soak in hydrogen peroxide (H2O2) or bleaching powder solution, and rinse with clean water before the next use.