In theory, beer yeast grows and reproduces under aerobic conditions and alcohol fermentation occurs under anaerobic conditions. Before entering the fermentation stage, the yeast needs to multiply to a certain number, and oxygen is required at this stage. This article will introduce the relevant content of wort oxygenation in beer brewing, as well as fully automatic, semi-automatic, and simple oxygenation equipment and methods.
Why is wort oxygenation so critical?
In order to enhance the dissolution effect of air in the wort, very fine air bubbles must be introduced and mixed with cold wort in the form of a vortex. Otherwise, if the air bubbles are too large, air will overflow from the wort, and the purpose of fully oxygenating the wort cannot be achieved. We must provide the yeast with enough oxygen (in the form of air) to make the dissolved oxygen in the wort reach 8~10mg/L. In the beer brewing process, wort ventilation is the only opportunity to provide oxygen to the yeast. The ventilation volume has a great influence on the quality of beer. If too much oxygen (greater than 12 mg/L) is introduced, yeast will multiply in large quantities, less ethanol will be formed, and the beer will appear thin; if too little oxygen is introduced, the dissolved oxygen content is too low (less than 6 mg/L), which will affect the reproduction and fermentation performance of yeast. In order to make the dissolved oxygen in the wort meet the standard, a large amount of air must be used. Theoretically, about 3L of air is required for every 100L of wort, and 10 times the amount is required in actual production because some bubbles are insoluble in wort; in addition, the distribution of the introduced air is not completely uniform. The compressed air must be sterile, so a sterile air filter must be installed before oxygenation. Unsterilized air will cause yeast contamination.
There are many ways to oxygenate wort. The following are the most widely used and effective ones:
Venturi tube
Using a venturi tube for wort ventilation is a common method used by many breweries. The venturi tube has a tube diameter constriction section to increase the flow rate, and the air is inhaled through the nozzle. The wort forms a vortex in the pipe diameter widening section so that the wort is fully in contact with the dispersed and fine air bubbles and mixed evenly. The use of a venturi tube can make the wort reach the dissolved oxygen content required by the process. The mixing ratio of wort to air is generally 1: (0.3~0.7).
Oxygenator with double-substance nozzles
The structure of the double-substance nozzle is similar to that of the venturi tube. Air is sprayed in through the fine nozzle on the pipe wall to form tight and fine bubbles. The technical requirements of its core part are: the wort delivery pipe diameter is 40~150mm, the wort flow rate is 25~200hL/h, and the oxygen supply is 10L/hL. The oxygen content of the wort can meet the requirements, and the effect of removing condensed matter can reach more than 60%.
New oxygenation equipment
For example, the new oxygenation equipment recently launched by Huppmann in Germany combines the advantages of the venturi tube for further upgrading. It will form negative pressure when working, and the wort and oxygen are fully mixed with the vortex effect. Its working principle is that air enters the wort in the form of a vortex through an air ring chamber nozzle, and oxygen can be fully absorbed by the wort. This nozzle can make the air form extremely dense small bubbles, so that the cold condensate and hop lees are effectively separated, and a dense bubble cover layer is formed on the surface of the liquid in the flotation tank. The turbidity in the wort is reduced, providing a good fermentation environment for yeast, and these devices often have glass sight glasses to observe the oxygenation of the wort.
It is worth noting that in the process of wort oxygenation, it is important to keep the oxygenation pipeline sterile. All oxygenation equipment needs to be connected to the CIP (cleaning in place) system and regularly sterilized with steam to ensure the safety and sterility of the entire oxygenation process, thereby ensuring aseptic production.
In short, in the process of wort oxygenation, whether it is the pursuit of automation, flexibility, or cost-effectiveness of the equipment, choosing the right oxygenation method for your brewery is an important step on the road to successful beer brewing. I hope this analysis can help you find the oxygenation solution that best suits your brewing needs. If you have any beer equipment needs, you are welcome to contact Tiantai at any time!
