I’ve written a few posts about pressure. Generally, I prefer a lower pressure as I find it leads to a creamier mouthfeel and less bloating. I thought my preferred pressure was in the low 30s. But with my most recent keg I’m running a PSI near 39. I’m not sure why but I can think of three possibilities:
First, my preferred pressure could vary by keg. With how big Guinness is, I would expect that the carbonation is very consistent for each keg that leaves the brewery. But maybe how the keg is treated has an impact. I know that temperature impacts pressure. Though I didn’t think that the temperatures a keg is exposed to would have that big of an impact on the ideal serving pressure. Maybe it does?
The second thing I can think of is that it is caused by switching gas tanks. I had to change the gas tank not long after tapping this keg. I was already adjusting the PSI higher before I changed the tanks. But perhaps the end of the tank caused that. Then, the new tank may have a slightly different concentration which causes me to want to adjust the pressure higher still.
The third possibility, and probably the most likely one, is that it’s all in my head. In pursuit of the perfect pint I need to be adjusting something and right now I’m focused on the PSI.
I’m not sure what the real reason is. I’m reminded of good coffee shops that start their morning by brewing an espresso with the recipe from the day before, tasting it, and making slight adjustments. For now, it’s something I want to try and track as go through more kegs. I’m plan start each keg at a PSI around 30. Then adjust it to my liking and see where I end up.