Best Practices - Oxygenation
Why do I need to oxygenate (aerate) wort?
Yeast needs oxygen for optimal growth. Yeast uses wort dissolved oxygen to build sterols and new cells, ensuring that "many hands do light work" in your fermentation. This helps you avoid off-flavours, speeds up your ferments, and ensures that enough yeast grows in your fermentor so that you can crop and repitch the next batch. Not enough oxygen leads to an increase in lag time, slower fermentation, or may lead to the production of undesired components, such as acetaldehyde or vicinal diketones.
Prefer video/audio? Check out our YouTube video here!
Which yeasts benefit from more oxygenation?
For more info on specific requirements of different yeasts, check out the sister article Oxygenation Requirements (ppm).
What do I need to know about oxygenation?
For Homebrewers, we recommend a simple "oxygen wand" setup available from homebrew shops. Shaking or splashing will give you at most 6 parts per million of dissolved oxygen, which is not optimal for many of our yeasts. Investing in a proper oxygenation setup is a relatively affordable way to see huge improvements in the quality of your homebrews. In general, you can get very good dissolved oxygen levels in well under 1 minute of oxygenating a 20L/5 gallon batch.
For Pro Brewers, we provide more thorough advice below, as there are many more considerations for oxygenation in the pro brewery that might result in your dissolved oxygen levels being much lower than expected or calculated, resulting in poor yeast performance.
Minimum requirements for adequate oxygenation in the pro brewery:
- A clean and properly sized oxygenation stone - inspect for blockage regularly, and treat these like consumables. Over time the pores can degrade. Replace every 2 years.
- Oxygen flow meter. We strongly suggest using a flow meter after your oxygen tank and regulator so that you know how much oxygen you are putting into your wort. A flow meter measuring 1-3 lpm (litres per minute) is typically sufficient for most applications.
- At least 25 ft and preferably >50 ft hose run from point of aeration to FV to allow for better dissolving of oxygen bubbles into the wort.
Suggestions for oxygenation in the pro brewery:
- Set your flow meter to 1-2 lpm at 15-20 PSI.
- Ensure you are getting turbulence in your hose run so that the bubbles have a better chance of dissolving.
- Having a pipe bend or elbow after the point of oxygenation can help add turbulence and dissolving oxygen bubbles. This design could be easily mimicked using common brewery parts.
- Add back pressure on the fermentor (using e.g. a spunding valve) if you are transferring under 10hL, or if this is the first fill of the tank. Hydrostatic and other forms of pressure make a big difference in oxygen solubility!
- Wort-level DO meters are surprisingly affordable! You don't need a $10k device to measure wort dissolved oxygen.
- If you have a Cbox or other ppb-level (packaged beer) DO meter, it may read up to 9900 ppb, which equals 9.9 ppm. So these meters can be used to verify wort DO up to 9.9 ppm.
- In-house, we use a handheld DO meter to validate DO levels in our propagation tanks. Good quality handheld DO meters can be found used or new in the $500-2000 range and present a clear ROI to the brewer in terms of healthier yeast and more consistent beer resulting in fewer surprises. Choose a meter that has easy to replace probes and that is easy to calibrate.
- How you measure DO is important. Sticking the probe in wort teed off from the bottom of the tank might give you misleading readings. We recommend measuring wort DO from the sample port once your wort has reached the sample port. We have measured DO by flowing aerated wort through a homemade rig (below) and floating the probe in the flowing wort. This should be achievable in most commercial breweries with minimal wort loss.
Oxygenation Specifics for Multi Brew Fills
- Pitch the yeast on the first fill and oxygenate each subsequent fill.
- The yeast will take up the DO you add in less than an hour, so you don't need to worry about oxidation.
- Unpitched wort will consume DO and oxidize as there are oxidizable components in the malt and hops.
- If you only oxygenate the last fill, you'll be under-oxygenating your wort and stressing your yeast.
What impact does temperature have?
Oxygen is more soluble at lower wort temperatures. As a result, if you are pitching hot with kveik or saison yeast, we suggest bumping up your oxygen flow rate to compensate.
We sometimes see brewers experience more fermentation problems in the cold winter season. One possible explanation is that cooler groundwater means a faster coolout and transfer, with the inverse effect on dissolved oxygen. We suggest brewers adjust the flow rate of cooling water so that coolout times are consistent throughout the year if possible, to avoid introducing another variable into the brewhouse.
This MBAA podcast with Derek Dawson at Modern Times details their steps to dial in dissolved oxygen for hoppy beers.
Our very own Nate Ferguson covers how to properly aerate your wort on YouTube.
Multi-filling tanks? Check out our Blog Post.