And am I supposed to wait for it all to settle before that first sip?
In: 8
Bubbles. You’re seeing bubbles of nitrogen. Most of the air you breathe is nitrogen, so if you want to drink nitrogen take a sip and feel the gentle frothy smoothness of bubbles on your lips and cascading down your mouth hole. It adds feeling and it can add to the way you taste something because it is essentially aerated so your pallette will pick up different things than if it was just plain liquid.
It’s the same process as forced carbonation except carbonation produces a much larger bubble and fizz feeling, which is weird in things like coffee or smooth rich stout.
Liquids will absorb gasses from the atmosphere, and the amount they absorb is based on the pressure on the liquid. So in the case of sparkling drinks we are intentionally exposing them to a high pressure atmosphere during packaging to force in tons of dissolved gas, and then when you pour the drink it’s suddenly exposed to a much lower pressure (normal room atmosphere) so the gases suddenly want to escape out. The ability for a gas to escape is based on how much of *that gas* is already in the room atmosphere. Phew, ok so that’s the science.
In the case of carbonation we are dissolving tons of carbon dioxide gas into the liquid and there is very little carbon dioxide in our normal room atmospheres, it’s about 0.04% of the air you breathe. So drinks that are carbonated are very, very fizzy because all the CO2 both wanting to *and capable of* leaving the liquid and entering the air quickly.
In the case of a nitrogenated drink we are adding nitrogen gas, N2, not carbon dioxide gas, CO2. The same basic event happens, the nitrogen wants to leave the liquid, but the air around is has tons of nitrogen already in it, air is about 78% N2. So the nitrogen *wants* to leave but it *can’t*.
So the nitrogen bubbles in your drink all rise up, just like a carbonated drink, but when they reach they surface of the liquid they can’t escape. So the new gas bubbles rising up will push the already-on-the-top-bubbles away and to the sides of the glass and then back down the sides of the glass to the bottom simply because there is no where else to go. They then try and rise up again, pushing against the bubbles on top, etc, etc etc. So you get that cascade effect.
It’s perfectly fine to drink while the cascade is still happening but it’s usually too pretty to drink and you sit and watch it for a moment.
What you are seeing is called a “cascade”. While it looks like there is some sort of “settling” downward, it is actually just bubbles (of nitrogen, a harmless gas that makes up most of the air we breath) rising. The apparent downflow is an affect cause by density waves; areas with more bubbles are lighter, and the bands of darker color just have fewer bubbles. So while the bubbles all rise, the density waves appear to be going down.
You don’t have to wait for the cascade to end, but you are expected to. First, it is the way the brewer intended the drink to be enjoyed, and second it shows you aren’t an addict who can’t just wait to get your fix. 😉
Here is some info, specifically about Guinness: https://www.youtube.com/watch?v=qNBTygWcy0s
Edit: There was some researching into what was actually going on.
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