Views:897 Author:Auril Publish Time: 2020-12-25 Origin:Site
Beer sterilization methods and their advantages and disadvantages
In order to ensure the biological stability of beer and facilitate long-term storage, the beer will be sterilized.
At present, there are three main beer sterilization methods used in production: flash pasteurization, tunnel pasteurization. and sterile filtration: these three methods have their own advantages and disadvantages.
Any sterilization method is to kill live yeast and bacteria in beer by heating. As long as the operation is standard, the biological stability of beer can be improved, and the beer can be stored at room temperature for several months without deterioration. The same goal can also be achieved by using aseptic filtration.The basic principle is: let beer pass through the filter to remove microorganisms in the beer.
When tunnel pasteurization is used, bottled beer or canned beer is sent to the sterilization channel through a conveyor belt. In the sterilization channel, spray hot water to make the temperature of beer reach 60°C,then keep it for 10 minutes, and finally spray cold water to cool the beer.
When using the flash pasteurization method, the beer is passed through two heat exchangers. In the first heat exchanger, use hot water to heat the beer to 71°C and keep it at this temperature for 20 seconds. Then use the second heat exchanger to cool the beer.
These three sterilization methods have their own advantages and disadvantages. They will damage the flavor of beer. The key question is "To what extent do these sterilization methods damage the flavor of beer?" and "How do they damage?"
Sterile filtration will weaken the mellowness of beer, affect the flavor of beer, and reduce the color of beer. The tight filter can intercept all the macromolecular substances in the beer, such as protein, dextrin, melanoidin. These substances give beer a certain taste, color and flavor. Therefore, aseptic filtration is more suitable for the production of light beer (such as the products of several large beer manufacturers in the United States). It is not suitable for the production of dark beer and beer with a strong sense of mellowness. Insteard of using a microporous membrane with a pore size of 0.22 nanometerss,some beer manufacturers produce bottled pure draft beer by using a microporous membrane with a pore size of 0.65 nanometers,to minimize the damage caused by aseptic filtration to the flavor. In fact,this method involves a certain risk. Some rod-shaped bacteria may not be removed and will remain in beer.
Pasteurization has caused certain damage to beer because it accelerates the oxidation of beer: the degree of damage depends on the sterilization temperature, sterilization time and potential oxidation of the beer itself. Obviously, the less air in the bottleneck and the more properly handled hot wort, the less damage caused by pasteurization. It is worth mentioning that, in spite of this, pasteurization will still cause some damage, but its negative effects will not be immediately revealed.
In terms of promoting the oxidation of beer, by contrast, the damage caused by flash pasteurization is less than tunnel pasteurization. Although the temperature during flash sterilization is higher, the duration is short. In addition, the instant sterilization is carried out before the beer is filled, so the dissolved oxygen when the beer is heated is relatively small. Flash pasteurization, like sterile filtration, requires aseptic filling. If the beer that has undergone flash sterilization and aseptic filtration is contaminated by bacteria during filling, the bottling beer will not have biological stability. Aseptic filling production lines and filling workshops must be kept clean like a hospital operating room and surgical tools.
As for which sterilization method to use, certain investigations are needed. Compare the pasteurized beer of various ages, such as one month, two months or three months, with the beer that has just been filled tO evaluate the oxidation stability and pasteurization damage of beer. The initial cost of using aseptic filtration is relatively low, but the filter medium is expensive and the replacement cost is high. In the long run, pasteurization is relatively inexpensive. Each sterilization method can produce beer with stable quality, but each has its own advantages and disadvantages. Manufacturers should make trade-offs based on their actual conditions.
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