Introduction
This is the sixth post in a series where I will try to find what (to me) results in the best pint of Guinness. First up I plan to test different aerator discs. Eventually, I will test different faucets, pouring methods, and glassware.
Part of the process of pouring a nitrogen beer is pouring it through an aerator or creamer. This is a disc with holes punched through it that the beer is forced through. In theory, the size and number of the holes could have an impact on what ends up in your glass. To test this out I purchased a set of aerator discs. This test is comparing a disc with three 0.7mm holes to a disc with five 0.3 mm holes. The 5×0.3mm disc is the only disc I haven’t tried so far. I would be surprised if it dethrones the 3×0.7mm disc as my favorite, but like any good scientist, I’m doing my best not to bias myself towards a specific result.
Testing Method
- Each disc is installed on a different stout spout. This is just to make switching between pours easier. Other than the disc, the spouts should be the same.
- Before pouring a pint I will run off some beer. This should ensure that there are no variations in the temperature of the faucet between the first and second pour.
- I poured each Guinness by holding the beer close to the faucet at a about a 45 degree angle, aiming to hit the center of the harp. Beer was poured until it reached near the top of the glass (while being held at a 45 degree angle) then I set a timer for two minutes. When the timer went off I poured the beer straight down while pushing the tap handle forwards until beer reached near the top of the harp then pushed the handle backwards to top off.
- Once each beer was finished I let them rest for to let the temperature stabilize.
- I did my initial tasting without knowing which pour was which.
Comparison
Up first is the disc with five 0.3mm holes. Compared to the other 0.3mm discs, the extra holes really made a difference. The flow rate was around 7-8 grams per second. And it took about 20 seconds to reach the bottom of the harp and 30 seconds to reach the top of the glass while the glass was held at an angle. So roughly half the speed of the disc with three 0.7mm holes.
The pour with the three 0.7mm holes was the same as it has been in past tests. About a 15 grams per second flow rate, 10 seconds to the bottom of the harp and 15 seconds to the top of the glass.
Side by side they look similar. The Guinness poured through the 0.3 mm disc seems to have more bubbles. It’s on the left in this image:
But from the top down it’s the opposite. With the beer poured through the 0.7mm disc having more bubbles and the one poured through the 0.3mm disc looking smoother:
Conclusions
When I tasted blind, I was able to correctly guess which pour was the 0.7mm disc. The Guinness poured with the 0.3mm disc did not have as dense of a head. A sample size of 1 is not statistically relevant, and I have no idea if I would be able to reliably pass a triangle test. But in this tasting, I once again preferred the disc with three 0.7mm holes.
I feel like a crazy person. I’ve been looking for the tiniest of differences in the way Guinness foam settles or in the pints mouthfeel. At the end of the day, I don’t think the architecture of your aerator disc is going to have much of a difference beyond how long it takes to pour the beer. Especially if you’re comparing discs with similar amounts of total area for allowing beer to pass through like the 5×0.5mm and the 3×0.7mm discs. The other variables like temperature, pressure, and clean lines are going to make a much larger difference on how you perceive your pint. But I did these experiments with the goal of finding out my preferred aerator discs. And after testing all seven, I’m ready to crown the disc with three 0.7mm holes the winner. At least for someone with my taste buds. And that’s the disc that I will use going forward.
Next up, I want to do some testing with different faucets. I’m not sure if I will do A-B testing like I did with the discs. I’m not sure that the faucet will change much in terms of how the pint tastes. But if something really wows me then I’d consider a blind comparison. More likely, I’ll just use each one for a bit and see if there are any differences in behavior.