I finally got a new keg. My last keg kicked on the 28th of May. I had been holding off on getting a new keg as a) I had some local brews in the fridge and b) I wanted to make sure I didn’t kick it just before the 4th of July weekend. Now that I have a new keg, I can continue my experiments with dialing in my perfect Guinness. Originally, I had planned to start testing different faucets. But I decided to play around with PSI instead.
I generally prefer my beer served at a lower PSI. Especially a beer like Guinness. I find that it increases the perceived creaminess and causes less bloating. I’ve tried adjusting the PSI on previous kegs and I’ve found that a lower PSI is better for the first few sips- especially if you prioritize creaminess – but it can taste a little flat near the end of the pint. Conversely, a higher PSI tastes less flat but the mouth feel is more prickly carbonation than smooth creaminess. A higher PSI also results in a larger amount of head. I care less about head size with the home kegerator as I’m not paying by the pint. But if you’re looking for a certain aesthetic then you may want to avoid adjusting the PSI too high and pouring a pint with two inches of head.
For reference, here are all of the variables in my home setup that might have an impact on carbonation (or perception of carbonation):
- I keep my kegerator at 42 F. In testing, I have noticed that this means that the actual temperature ranges from 40 F to 44 F (~ 4.5 to 6.5 C)
- I am using a blend of 75% Nitro and 25% CO2.
- I am using an aerator disc with three 0.7mm holes
- My beer line is around 3.5 meters or 12 feet long.
- My altitude is ~35m.
When I first tapped this keg, I set the PSI around 25-26. I was not a fan of this. It tasted okay but it just did not pour smoothly. At least not audibly. It sounded like it was sputtering. I thought it might have been because it was the first beer of the keg but I poured four or five and none sounded good. As for taste, it was fine. Maybe a little flat at the end as expected.
The next day I poured my first pint at the same 25-26 PSI to remind myself how it tasted. For the second pour, I adjusted the PSI to around 28 or 29. I thought this was a fantastic pour. Very creamy. Fantastic lacing. Still a little flat at the end but that’s the trade off for the creaminess.
The next day, I again kept the PSI unchanged for the first pour. Then adjusted it up to around 30 for the second pour. I was floored by the difference in the first sip. There was still some creaminess. But it was starting to taste more like the pints you get a lot in the US: vibrant carbonation, but lacking in mouthfeel and depth of flavor.
I don’t like to try and do critical tasting after adjusting PSI downwards. I trust my regulator to add pressure to the system; but when adjusting downwards I worry that I’m going to get some pours at the higher PSI until some of the CO2 comes out and the regulator can start adding it back. I have no idea if this is how it actually works. Regardless, I don’t try to turn down the pressure when doing comparisons.
When I get my next keg, I plan to set the PSI around 29. Then, maybe three fourths of the way through the keg I’ll kick it up a few PSI and see if see the same very noticeable difference. If there is, then I’ll stick with ~29 PSI for all my future kegs.