Frivolous Friday Fun – A Robotic Segway Beer Delivery Cart

Our friends in the Netherlands are an inventive bunch, having come up with the microscope, the telescope, the mercury thermometer, and gin. Now here’s their latest essential invention, brought to you by the department of Robotics and Mechatronics at the University of Twente: a remote controlled Segway beer delivery cart. Step aside, microscope and all the rest, the REALLY important invention has arrived! Click HERE for the link.

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Total Package Oxygen 101 – TPO Calculation

For the past several posts we’ve been talking about calculating TPO using dissolved oxygen values on shaken packages. Now let’s go for it, and talk about the calculation itself.

The standard reference TPO calculation in use today first appeared in a 1985 article in Brauwelt. There’s a lot of math behind this, so if you want to really understand all of the parameters then it’s well worth looking up: C. Vilachá and K. Uhlig, “The Measurement of Low Levels of Oxygen in Bottled Beer,” Brauwelt International (Volume 1, 1985), 70-77. In the meantime, let’s dissect the calculation and then talk about how you can get an excellent approximation of the TPO using your dO2 measurement. Here’s the equation:

m (t) = total oxygen in mg

X = oxygen content of the beer mg/L (or ppm dO2)

T = Temperature degrees K

The table below shows the dO2/TPO Ratio multiplier you need to apply to your dO2 to get your TPO.  As you will see in the table, the multiplier or dO2/TPO Ratio is very dependent upon the package temperature and headspace volume.

Package Type

Liquid

Volume (mL)

Headspace

Volume (mL)

Temperature

Degrees C

 dO2/TPO Ratio
12 Oz.

355

17

5

2.1

12 Oz.

355

22

5

2.4

12 Oz.

355

17

20

2.4

12 Oz.

355

22

20

2.9

22 Oz.

651

25

5

1.9

22 Oz.

651

25

20

2.2

22 Oz.

651

35

5

2.2

22 Oz.

651

35

20

2.6

So let’s pick an example from the above table, and do our calculation. If you have a 12 oz. package with a 17 mL headspace and you are measuring at 5 degrees C, multiply your dO2 by the ratio of 2.1 to get your TPO. We’re using 100 ppb  (0.100 ppm) in this example.

dO2 x  dO2/TPO ratio = TPO     such that     0.100 mg/L x 2.1 = 0.210 ppm TPO

My final thought is that if you have tight TPO specifications or really want to track everything back to a LIMS system, then a TPO analyzer is the right choice. Otherwise, using a calculator in an excel spreadsheet will get you an equally accurate concentration if you know which parameters are important.

If you would like a copy of a TPO calculator that works in excel, leave a comment and I will email one to you.

Dissolved O2 Pickup from Fillers vs. Crowners or Seamers: Quick Tip on How to Tell the Difference

In follow-up to my June 20th post about the difference between dissolved oxygen and TPO, I want to share a conversation I recently had with a customer about the dO2 results he was seeing on his canning line, and the way simple dO2 measurements of shaken and unshaken packages were able to help him sort out a problem.

This brewer was doing a good job of getting his beer to the filler — he reported having less than 10 ppb going into the filler — but he couldn’t understand why he was then seeing shaken package dO2 levels that were high and unpredictable. So I asked about his filler pick-up in an unshaken can. Filler pickup is equal to unshaken dO2 minus the base of the filler dO2. He said it was about 40 to 50 ppb, but his shaken dO­­2 ranged from 300 to 600 ppb and was sometimes higher.  So where was the oxygen coming from, and why?”

I told him that the oxygen had to be coming from air trapped in the foam, then did a quick calculation to show that it really could rise that much. If all of the headspace in a 12 oz. package were air, the can or bottle would pick up between 3 to 5 ppm of oxygen, depending upon the size of the headspace: the more air that got into a particular package, the higher the shaken dO2.

Here is a quick tip to help you easily sort out if the bulk of your oxygen is in the headspace or the liquid. Since packages are not at equilibrium just after canning, the dissolved value of the container is going to either increase or decrease, depending where the majority of the oxygen is at the time the closure goes onto the package. If you measure the unshaken dO2 and then the shaken dO2 and follow these two simple rules, it will quickly lead you to the answer:

  • If the dO2 of the package increases, the majority of the oxygen was in the headspace – it shifted from the headspace to the liquid upon agitation.
  • If the dO2 in the package decreases, the majority of the oxygen was in the liquid – it shifted from the liquid to the headspace upon shaking.

My final thought is that a simple test like comparing the dO2 on shaken and unshaken packages can tell you a lot about where to focus your troubleshooting effort.

 

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