When it comes to questions about oxygen in beer, I think the one I’m asked most often is, “What is the difference between dissolved oxygen and total package oxygen (TPO)?” The main source of this confusion is that when measuring O_{2} in packages, the O_{2} in the headspace is often overlooked. If you don’t take headspace oxygen into account, then you are measuring a partial concentration, period. So let’s talk about the differences and what each one tells you.

A significant number of craft brewers have a dissolved oxygen (dO_{2}) analyzer they use to measure the dO_{2} content of their beer *in process*. The most common point of measurement is the finished beer tank. The beer in a finishing tank will have O_{2} pickup from the empty vessel and from the filtration process, plus it will pickup more O_{2} as it goes through packaging.

Once the beer is packaged, however (assuming good packaging,) rapid O_{2} pickup from outside sources all but stops. So what can we tell about how much oxygen actually made it into the package? It is not a simple matter of measuring the O_{2} in the beer. The package must be *shaken* to equilibrate the oxygen in the beer and the headspace before the 0_{2} in the beer is measured, and that number must then be used to *calculate *your TPO. Let’s think about what it is possible to measure and what each thing tells you.

**Package dO2 –**

The easiest measurement to take on packaged beer is the dO_{2} of a package just off the filler without shaking the beer. It is important to measure as quickly as possible, so the product does not “consume” the oxygen in the beer. (Residual or live yeast may be hungry, plus oxidation by trace metals, etc.) In some packages there is a measurable difference within five minutes and in other packages the rate of oxygen consumption takes significantly longer, sometimes hours. It is always best to measure as quickly as possible.

This unshaken package measurement represents the combination of the dO_{2} of the beer at the base of the filler and the oxygen pickup of the filler. Oxygen picked up at the filler can be quite variable. Most fillers run at about 25 to 50 percent deviation, but in some cases it can be up to 100 percent deviation. The best way to measure the percent deviation is to determine the dO_{2} at the base of the filler and then measure six to ten packages and determine the variation of each package as compared to the average of all the containers. But remember: this measurement only tells you what is in the *liquid*. When measuring unshaken packages, any gas in the headspace is left uncounted.

**Shaken Package dO2 –**

When you shake a package of beer so that the partial pressure of the oxygen in the liquid is equal to the partial pressure in the headspace, it changes the characteristics of the oxygen partitioning in the package. If most of the oxygen in the package is locked in the liquid, then shaking the container will move the O_{2} from the liquid to the headspace until equilibrium is reached.

So, you have measured the dO_{2 }and then shaken the package. Now what do you do with the data? If you really want to quantify the TPO of the package you have to take into account the headspace oxygen. To do this accurately you need to know the headspace volume and the package temperature.

**Total Package Oxygen –**

When using the dissolved oxygen measurement, the TPO can only be calculated from a shaken package. To do this calculation you also need to know the headspace volume, liquid volume and the package temperature. The temperature and the headspace volume are critical values and small inaccuracies can alter the results significantly, but the liquid volume may be estimated by using the average fill volume. Once you have your figures, then you can use a TPO calculator to determine the concentration from your initial DO_{2} measurements.

My final thought is to not skimp on how much you shake the packages. Cold containers should be shaken for five minutes and room temperature cans or bottles need about three minutes. If you’d like a copy of a TPO calculator built into an Excel spreadsheet, then please click here to request one.

Could i get the TPO excel spreadsheet. Thank you!

Please send top calculator.

Would love you check out your excel calculator

Hi Chaz. I really enjoyed your presentation at CBC last week. May I ask for the Excel calculator? Thanks.

Chaz,

I enjoyed your talk at the Craft Brewer’s Conference. I thought it was very informative. At one point during the talk you touched on DE being a big problem with increased DO. I was wondering if you or your compatriots have done any research into DO as a result of DE filtration. Do you have any tips for minimizing DO while operating a DE filter? Thank you for your time and expertise.

Kevin Walter

Please send the TPO excel spreadsheet!

Hi Mr Chaz,

I would like to have a copy of TPO calculator built in a Excel spreadsheet.

Thank you for all your good information on oxygen in beer.

This may be a silly question but you mention that in order to measure the percent deviation I need to know the DO at the base of the filler. My question is why? Do I use this number anywhere when determining the percent deviation? Do I subtract it from all of the bottle DO readings? Thanks!

Great post, my brother went to your conference during cbc and brought back plenty of info including yours.

Just recently bought a DO meter and would greatly appreciate the TPO Calculator to start measuring oxygen in our packaged beer bottles. thanks!

Can you send me your calculator. I found this article very helpful. And quite frankly, makes sense!

hi, could you please send the TPO calculator. thanks

Hi Chaz,

Thanks for the great article. We recently purchased an Orbisphere DO meter for our brewery and would appreciate a copy of your TPO calculator. Thanks again.

would like excel spreadsheet please

thanks! could you please send the TPO calculator.

Hi Chaz,

Great article, very informative. I am interested in getting a copy of your TPO calculator if possible.

Thank you!

Hi Chaz,

May I please get a copy of your TPO calculator. Thank you!

Hi! Can I please get a copy of the excel TPO calculator. Much Appreciated!

I would like the excel spreadsheet please

could i get of copy of the excel calculator

I would like to have a copy of TPO calculator built in a Excel spreadsheet.

Thank you for all your good information on oxygen in beer.

I would like a copy of the excel TPO spreadsheet, thanks in advance and thanks for the informative article!

CAN you send me a copy of your TPO spreadsheet?

Cheers!

hey chaz..can i get the copy of the TPO calculator on excel??

thanks

Could I get a copy of your spreadsheet?

Very interesting. Can I get a TPO excel spreadsheet to. Thanks

id love a copy of the calculator

Can you please send the excel spreadsheet to me please?

Interested in your TPO Calc. Thanks.

Could you please send me your TPO calculator.

Thanks!

I would like to try out your TPO calculator

Could you send me please your TPO excel spreadsheet, Thanks