Frivolous Friday Fun – Packaging Hype Gone Wild

 

 

One of the things I love about brewers is that they don’t take themselves too seriously.  While breweries have artists like Ralph Steadman designing their labels, champagne makers use glitz and glamour to sell their product. To see the latest package blitz by Dom Pérignon click here.

 

 

TPO Measurement: the Importance of Methods Validation

Total Package Oxygen (TPO) can be such a confusing topic that it’s worth an ongoing discussion. Since real-life examples are often the easiest to grasp, today we’re going to look at TPO from the perspective of a brewer who is actively trying to troubleshoot his new seamer. Even if you aren’t canning, you should be able to apply this information to problems with a bottle filler.

In this case, the Brewer has purchased a new seamer that is specifically promoted as keeping TPO low, and yet his TPO measurements after seamer installation are nowhere near as low as the seamer company says they should be. When the brewer and I talked, I was immediately struck by what the seamer people had provided as the target TPO: 20 ppb, which is super low by any standard. So our next step was to try and understand the origin of that number.

The seamer manufacturer really wasn’t able to tell our brewer why his values were not meeting expectations for the seamer. After some initial probing, it turned out that the seamer people were sincere in their beliefs about the abilities of their seamer, but they didn’t have a lot of experience with beer, and had based their numbers on data from only one other customer. Knowing this, we then formulated some questions for that customer.

We’re still waiting to hear back, but here’s what we’ve asked:

  1. What was the reading from the package when measured on their dissolved oxygen analyzer?
  2. Was the package shaken or unshaken?
  3. If the package was shaken, did they calculate the TPO from the dO2?

Here’s what the answers to each of these questions should tell us:

  • If the answer to the first question is in the range of 7 to 10 ppb, then it really is in the realm of possibility that their TPO is 20 ppb, as long at the instrument was validated (more on that in another post), the package was shaken, and they did a correct TPO calculation.
  • If the answer to the first question is 20 ppb, then we need to know if the package was shaken. If it was shaken then it was at equilibrium, but did they calculate the TPO?
  • If the package was unshaken, then the value they were calling “TPO” was actually just the dO2. This represents only the oxygen concentration of the beer coming into the filler and the pickup in the filling process. To get the TPO, they still needed to measure the dO2 on shaken packages and calculate TPO based on the dO2, package temperature and the liquid and headspace volumes.

It will be interesting to see what happens, but my guess is that the numbers provided to the seamer people – and thus to our brewer — were not TPO. They may be shaken or unshaken DO2 – both are possible.

My final thought is that when someone tells you a dissolved gas value upon which you must rely, ask how it was derived. The reliability of measurement is only as good as the validity of the method by which it was obtained.

Total Package Oxygen 101 – TPO Defined

 

The following popular post was the first in a series covering Total Package Oxygen (TPO). The blog is still on vacation, but I’ll be back at it Friday with a new Frivolous Friday post. 

In the late 1980s I worked on a research and development team — funded by a crown manufacturer — with the goal of creating oxygen-scavenging polymers for beer bottle closures. The project went through numerous challenges (think scorched plastic) and dicey prototypes (think raised eyebrows at the FDA). In the end we were successful, but by far the biggest and most important challenge was learning how to quantify the efficiency of our oxygen scavenging polymers. In other words, exactly how much oxygen did the polymer coated closures remove from bottled beer?

It turned out that the ticket was to measure Total Package Oxygen (TPO). We’ll talk about our method in a minute. But first, what exactly is TPO? Simply put, TPO is defined as all of the oxygen in the package: headspace and liquid. We can also just say that TPO is all of the oxygen available to react with beer in a package. In order to get an accurate TPO, we need to know four things: dO2, headspace volume, liquid volume, and temperature.

We’ll cover the importance of volume and temperature in a future post, but for now let’s talk about the first parameter: dissolved oxygen. For our project, we knew that measuring headspace oxygen alone wouldn’t do, because experience had taught us that beer itself has a really fast oxygen uptake, and we needed to know how well our polymers were scavenging.

So we thought a bit more about the oxygen content of a package just after filling. We already knew we had gas in the headspace of the bottle or can, and gas dissolved in the liquid. The dissolved oxygen was whatever was present in the beer before filling, plus any oxygen picked up during the filling process. The headspace oxygen, on the other hand, was air left over in the headspace after a closure was put on the bottle or can.

So there we were, with two distinct partitions of oxygen in the package — dissolved and headspace – and yet we wanted to measure using a portable dO2 analyzer. How were we to do that and still take into account the headspace O2? It turned out that the answer was a bit James Bond: the package needed to be shaken. (Not stirred!) We found that if we shook the packages properly, the gas in the liquid and the headspace would equilibrate to the same partial pressures. Once the gas was at equilibrium, we could use our portable dO2 analyzer to measure the dO2 in the liquid.

Since then, many TPO techniques have been developed that measure variations of dissolved oxygen, headspace oxygen, and a combination of headspace and dO2.  Different techniques have different advantages, but for now I just want to assure craft brewers that it is possible to do accurate dO2 measurements in pursuit of a TPO goal using one of your simplest tools: a portable dO2 analyzer.

My final thought is to emphasize the importance of making sure your packages are at equilibrium. If a can or bottle is not properly shaken, then your TPO may be either under or over estimated.

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