How to correctly control the oxygenation method and oxygenation amount of cold wort?

Aeration of cold wort seems to be a very simple process, but the way of aeration of wort and the control of aeration of wort are crucial to the normal fermentation of yeast, smooth production process, quality stability and flavor characteristics of beer products. If the oxygen is not properly filled, it will cause a series of changes in the fermentation process, and even lead to bad fermentation results and flavor defects.

(1)Control of wort oxygenation amount 

The oxygen content of wort is controlled according to the degree of oxygen demand of yeast species and fermentation process. The oxygen demand of different yeast species and fermentation state is different.

The conventional practice is to control the dissolved oxygen in the cold wort at 5 ~ 8mg/L, and the necessary adjustment can be made according to the actual needs of yeast reproduction, rarely exceeding 10mg/L. The oxygen charging of wort is generally controlled by oxygen flow, pressure, time and oxygen filling equipment.

The effect of wort oxygenation is related to the control of oxygenation time. By using unqualified or simple oxygenation device, the actual oxygenation effect can not be achieved in most cases, and the oxygenation is not necessarily proportional to the actual dissolved oxygen content of cold wort. In this case, some beer lovers often extend the time of oxygenation to ensure the oxygenation effect.

In fact, the cold wort dissolved oxygen in addition to the oxygenation time, but also with wort concentration, wort temperature, wort temperature low, low concentration of the original wort, better oxygenation effect, oxygenation time can be appropriately short; The time of wort oxygenation is related to the oxygenation equipment used, aseptic air pressure and flow rate. The pressure is high, the flow rate is large, the emulsifying effect is good, and the oxygenation time can be shorter.

However, the actual oxygenation time controlled by mass production is not only combined with the dissolved oxygen content that needs to be controlled, but also with the dissolution and distribution of oxygen in wort. For example, the cold wort batch with yeast added is mostly full oxygenation, while the cold wort batch without yeast added can be oxygenated in stages, or the oxygenation time can be reduced or even not oxygenated.

As long as it can meet the dissolved oxygen needed for yeast reproduction, do not advocate excessive oxygen. The budding cycle of yeast is about 12h, and it should stop oxygenation after 12h. The budding yeast can synthesize linoleic acid by itself.

(2)The control of oxygen filling mode has the following aspects 

One is the location of aeration of the cold wort. The correct oxygenation position should be near the place where yeast is added, that is, a device installed on the cold wort pipe that can not only simultaneously oxygenate and add yeast, but also fully mix them. In this way, the oxygenated yeast has the best effect of contacting oxygen and absorbing oxygen.

However, breweries usually use the form of adding venturi tube on the cold wort pipe, before adding yeast, the cold wort is filled with oxygen, so that the cold wort containing dissolved oxygen into the tank, and then immediately carry out yeast inoculation, which is also a better way.

Secondly, in the wort cooling process, the wort can be oxygenated with a relatively small flow of the whole process, can evenly distribute the dissolved oxygen, it is not recommended to the wort large flow of concentrated oxygenation, the latter is not good at the dissolution of oxygen.

Thirdly, the batch wort with yeast can be oxygenated in the whole process or in stages, and the batch wort without yeast should not be oxygenated in principle. In consideration of the needs of yeast reproduction, for large fermentation tanks with multiple batches full of yeast, the batch with yeast can be filled with oxygen in the whole process or in stages. After adding yeast, the oxygen content of the next batch can be appropriately reduced, or the oxygen content and oxygen time can be increased or decreased depending on the yeast reproduction.

If there are more than one batch of wort into the tank, the last batch of cold wort into the tank may not be oxygenated in principle. However, if it is found that the wort in the can is not uniform, it can be filled with sterile air with low flow rate and low pressure for 5-10 min.

Brewery fermentaion tanks

The step of oxygenating wort is also an important part of the whole brewing process.If you want to know more information for brewing beer process,please contact me.We not only understand the brewing process but also a manufacturer of beer brewing equipment in China. You can purchase very satisfactory beer equipment from us, opening a new door to your beer business.

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