Any time that a beer is transferred from one vessel to another, it has the possibility of picking up oxygen. If done well, that amount can be infinitesimal. If it’s not done well, a whole heck ton of oxygen can get in. Before beer is sealed into a can, bottle, or keg, the total amount of oxygen the beer has picked up is called DO (Dissolved Oxygen). Whether or not there is any DO in the beer before packaging depends on how the beer was made: was it aged in barrels? Was it transferred through multiple containers? Did something go wrong?
Four drops of ink in one 55 gallon barrel is roughly 1 part per million. Four drops of ink in one hundred 55 gallon barrels is roughly 1 part per billion. We measure oxygen in parts per billion.
Though we keep DO as low as possible before its transition to a package, beer will always pick up at least a tiny bit more oxygen when it’s put into a bottle, can, or keg. The amount of oxygen that’s allowed in during packaging, however, is something that we work hard to minimize.
Why do we want less oxygen? When beer meets air, it begins to oxidize, causing undesired flavors. We have a sophisticated automated measuring device that precisely measures TPO (total package oxygen)—as well as a host of other things like hydrogen content, temperature, carbonation, and more. We run these TPO checks about once per hour during packaging runs, to make sure we have a solid cross-sample of that particular beer’s quality.
That big white machine with the bottle in it is used to measure Total Package Oxygen (TPO) among many other things.
Only after a package is sealed can we measure the TPO. As an example, the upper limit of extra oxygen that we’ll allow in our bottles during packaging tops out at 50 parts per billion. In practice, most of our bottles only pick up between 15 to 20 parts per billion. The goal is to create beer that keeps in the best possible condition for the longest amount of time.
Even after our beer leaves the brewery, we have information that will help us keep track of it. Every bottle and can we package is marked with a packaging time and date. Kegs are labeled with packaging times and batch numbers. This way, we know down to the minute when it rolled of our line. If we ever find a flaw in a particular bottle, we’re able to tell what batch of beer and the exact lot of glass it came from, as well as the other bottles that might be affected by that same issue. Add that to all of the information we record about the beer from brewing to fermentation, and we have a full view of a beer’s entire life. The end result is that if something were to ever go awry, we could pinpoint the problem down to the exact tank, tube, or bottle cap—and then trace that back to the stores/bars/restaurants where the beer ended up.
We hope this helps you visualize the breadth and depth of the work that goes into packaging our beer. Next up, we step into our sensory department.