I was talking to a brewer about TPO and he asked if minimizing oxygen pickup at the filler might help extend his shelf life and limit sensory changes as his beer ages. He was mainly concerned with controlling beer in the distribution channel, but when I quizzed him about how he calculates the pull dates for his product, he admitted it was mostly a guess. He said there were significant differences in his beer after it had been sitting on a shelf in a store, but he hadn’t tried to mimic that aging and study the changes in a controlled setting.
Oxygen pickup is definitely the most critical component in the development of off-flavors in beer, but many other things can be a factor too, so careful studies of the way your beer ages can help you make informed decisions. Here are some ideas that might help.
First, if you haven’t already done it, then consider getting formal training in sensory. You no-doubt know your product very well, but learning the standard terms and techniques of sensory can be a lot of fun and can give you a good foundation to stand on as you start keeping records. I was with a company that hired a sensory specialist to come in and work with us over the course of a year and it was some of the most valuable training I’ve ever received.
Next, set up a system for comparing your stored beer in different environments over time. I once worked with a closure manufacturer to develop oxygen-scavenging polymers for crown closures. We established a taste panel to evaluate everything from how the polymer affected beer taste to how well the crowns worked to minimize oxidative flavor formation. Depending upon what we wanted to learn, we had different methods for beer storage and comparison.
Our most basic protocol called for storing a set quantity of the same beer (all from one run, one filler) in different ways, typically one case stored cold, one at room temperature, and another upside-down at room temperature.
The cold beer was the control, since sensory changes are accelerated by heat. The room temperature samples were to see what changes developed in non-harsh conditions. And the upside-down bottles at room temperature were to minimize effects of oxygen ingress through the closure, so we could see how well they worked. This can be done with canned beer too, but you shouldn’t need to store the beer upside down unless you are concerned with poor seaming.
Next, you can see how your beer responds to harsh conditions and other variables. Punish it by exposing it to heat, like might happen in a hot delivery truck. Or maybe you’re concerned about closure polymers affecting taste. To analyze this, gently heat lined caps on a hot plate and remove the liner material with tweezers as soon as it gets soft, then put them in the beer, fob it, and re-seal. When you taste it days or weeks out, you should be able to detect things like flavor scalping or off-flavor pickup.
Once you’ve established a system for storing and evaluating your beer under different conditions, make sure you check it on a regular basis. It’s probably not necessary to do it every day, but in addition to tracking sensory changes over time and in different conditions, it can be helpful if there is something in your process that changed, like a new source of ingredients or filling issues.
My final thought is to get to know your beer. Compare it with both beer packaged at the same time and with beer that is older or younger. By understanding sensory changing factors, you may be able to comfortably lengthen the time you beer is in the distribution channel by weeks or even months.