What Is The Foaming During Bottle Beer Filling

What is foaming in the bottled beer filling process
During the bottling process of bottled beer, there is a procedure called foaming. What is foaming? Why does beer need to froth?

1. Definition of foaming
   After filling is completed, before capping, the beer releases carbon dioxide by tapping the bottle, spraying carbon dioxide, using high-pressure water or dripping the beer into the bottle, etc. A fine foam is formed, which then rises and overflows out of the bottle to expel the air in the neck of the bottle. After that, the bottle is quickly capped and sealed. This process is known as foaming.

The most common method is to spray hot water into the bottle with a nozzle after filling the beer and then capping it. The foam produced expels air from the neck of the bottle, which will effectively reduce the amount of dissolved oxygen in the beer. The high-pressure hot water used for foaming is best maintained with the following parameters.
Temperature: 85°C.
Hardness. 4°dH.
Pressure: 1000kpa.
In addition, the high-pressure water should be filtered through a membrane filter and then heated to above 80°C. It must not have bad odor.

2. The need for foaming
   When the oxygen concentration in the beer exceeds 2mg/L, it will have a serious impact on the stability of the beer. For a 640 ml bottle, the amount of air at the mouth of the bottle is about 30 ml, which corresponds to an oxygen concentration of about 13.125 mg/L. This would be very detrimental to the flavor of the beer. It is therefore necessary to remove the air from the neck of the bottle. The solution is to froth the beer during the filling process. A good foaming can reduce the amount of air to 1.5 ml or even less. In this case, the oxygen concentration will be below 0.5 mg/L. Foaming is of great importance for the stability and service time of the beer.

After foaming, the capping time should be controlled during the foam overflow, not before or after it. Before foam overflow, there is still a lot of air in the bottle neck. After the foam overflow, there is also a lot of air in the bottle neck as the foam disappears. Therefore, the capping time should be controlled during foam overflow.