I just returned from the Craft Brewers Conference, so I’m going to devote today’s blog post to a question I heard a lot: at what point do dO2 and package O2 measurements become important? If you have a problem with oxidative flavor changes, then you probably want to measure dO2. But how do you know you have a problem?
The first thing I recommend is to take a good look at where your brewery is located and how you distribute your product. Do you know if you have negative variations from your expected flavor profile once your beer leaves the brewery? If you’re unsure, then ask yourself:
- Do I have control over how long my product is in the market?
- Is my brewery located in a region where beer can be punished due to warm storage or excessively hot shipping conditions?
Flavor changes due to oxidation usually become noticeable one to three months after packaging. Flavor changes due to heat become noticeable much sooner, and can be exacerbated by high oxygen levels before and during packaging.
To see if your beer is susceptible to flavor changes, grab a batch sample of bottles and store them three ways:
- A third at room temperature with the bottles upright.
- The second third at room temperature with the bottles upside down.
- The rest should be kept cold below 40 °F.
For cans, just keep samples at room temperature and cold, no need to turn any upside down.
Then, compare the flavor profiles of each storage type monthly, looking for changes. You can experiment by storing some at higher temperature conditions too. This accelerates changes, but they won’t always mimic what happens over an extended period at room temperature.
The cold samples should reflect your expected profile most closely. The upright and upside down bottles may start off similarly, but diverge over time due to oxygen ingress through the closures. In that case, you may want to examine closure types or crimp pressure. Cans should not have ingress issues, so any flavor changes will most likely be due to storage conditions and previous oxygen exposure.
My final thought is to know your product and how the flavor evolves. Two decades ago I had a brewer tell me that he knew his beer changed significantly over time, but he wasn’t sure it was a bad thing. Maybe it wasn’t bad for him, but what about his customers? Do your customers want consistency? If you can distinguish flavor changes over time, then your customers probably can too.