Why and how to oxygenate the cold wort?



We all know the beer yeast is aerobic-anaerobic microbe, it will multipling under aerobic condition and fermenting under anaerobic condition. Before the yeast enter into fermentation stage, they need to multiply to reach a certain amount with oxygen.That is why we need to oxygenate the cold wort, and make the dissolved oxygen reach 8~10mg/L.

In order to facilitate the dissolution of the oxygen, the air must be bubbled with very small air bubbles and mix with wort in the way of vortice. In theory, every hundred liter wort will need 3L air to reach dissolved oxygen 8~10mg/L, but in fact 10 times during actual production. Cause part of the air which did not dissolved in will be discharged, the bubbled air is not even acturally. Besides, the higher temperature of the wort, the lower dissolved oxygen will be.

The oxygenate unit is mounted the outlet of the heat exchanger in general, and the air enter into the oxygenate unit after going throught the air flow meter and air filter. The wort enter into fermentation tanks after it totally mixed with air. The common used oxygenate unit is Venturi tube. As below picture:

Both ends of the Venturi tube with bigger section than center section(deflation part). When the wort flow throught the deflation part, the flow rate will be higher because of the smaller section.The sterile air which is bubbled in deflation part will be indraft in wort soon, form many micro bubbles and dispersed in the speedy wort evenly. The vortex will be formed at the bigger section part, it is good for the wort complete contact and dissolved with those bubbles.