Oxygenating Wort Multiple Times
Should I oxygenate my wort multiple times?
Multiple rounds of oxygenation can be useful in some specific contexts:
- Where adequate oxygenation is not achievable upfront (e.g. aeration with compressed air instead of pure oxygen)
- Where additional yeast growth is required for optimal fermentation (e.g. in high and very high gravity brewing this can be beneficial)
- Where the particular yeast strain has a high demand for oxygen for fermentation completion (e.g. in traditional Ringwood breweries)
- Where oxygen solubility is lower such as high temperature fermentations (over 26ºC)
Additional oxygenation is not useful in these contexts:
- Where the yeast has already exited lag phase and is actively fermenting sugars (oxygen helps with yeast growth so if the yeast has already finished growing, there isn't much benefit to oxygen)
- Most normal gravity worts with most yeasts (unnecessary)
- Restarting a stuck ferment (better to use additional nutrients, rousing, krausening, dry yeast, or other means to keep the ferment moving)
In general, if you plan to do multiple rounds of oxygenation in your beer, our advice is to oxygenate the first time when the yeast is pitched, and then again no more than 12 hours later. In our experience with high gravity brewing, a second dose of oxygenation can help with yeast growth and therefore yeast health and fermentation efficiency.
Additional Resources
Regarding available research on timing of oxygenation, there are some references in this blog post on multi fill brews. While that blog is more relevant to multi-fill brewing, the references cover some different oxygenation techniques.