To start, let’s look at a curious little molecule called CO2 – you know, the thing that trees breathe.
And you know, CO2 isn’t always a popular molecule, right? We constantly hear ecological reports saying that we need to drastically decrease our global CO2 emissions in order to curb global warming, so there’s that. But when it comes to beverages, CO2 is the molecule most often responsible for activating your trigeminal nerve with its fizzy, tickly little bubbles.
The trigeminal nerve, of course, is the nerve responsible for sensation in the mouth and head. It communicates feelings like spiciness, cooling, and tingling to the brain. And the bubbles in your drink are there because at some point before it got to you, someone dissolved carbon dioxide in your water, producing a compound called H2 – CO3 – AKA, carbonic acid. So if you’ve ever noticed that carbonated water tastes a bit more acidic than normal water – you’re right, and that’s why. Acid.
Now, there’s a reason why carbonated beverages go flat when you leave them open, and that’s because, in order for CO2 to dissolve optimally (and stay dissolved) in water, the liquid has to be really cold (but not frozen), and everything has to be done in a closed system under a great deal of pressure. When you first open your carbonated beverage, the CO2 starts to escape, and as long as your beverage stays reasonably cold and you consume it in a reasonable amount of time, you get the benefit of those nice tingly bubbles to spice things up.
Joesph Priestly and the History of Carbonation
One great story about the history of carbonated water is that in 1767, a British dude named Joseph Priestly decided he was going to suspend a bowl of water above a fermenting batch of beer. And if you know how fermentation works, you know that yeast produce two substances when they eat sugar: alcohol and CO2. So when Joseph Priestly came back to his water and tasted it, he found that it was lightly bubbly, and this, of course, was pleasant to him.
Then he went about optimizing this process using bellows and various air bladders, and he would eventually go on to publish the rapiest sounding scientific paper ever, entitled: Impregnating Water with Fixed Air.
Flavor in Water
Of course, we all like to think about water as essentially flavorless, but that just ain’t the case. The primary culprits that affect water flavor tend to be minerals that are dissolved in that water either due to the mineral composition of the aquifer from which the water is drawn, or due to human intervention – for better or worse.
Lots of people like to fiddle with the chemical makeup of their water for a desired outcome. Starbucks does it with their coffee, brewers and distillers do it with their booze, and there’s even this odd cultural notion that the water in New York city is responsible for the quality of their bagels. I’m still skeptical of that last one (since the water in New York today is radically different than it was when the first bagels were boiled), but I think it’s safe to say that when you drink a glass of water, most of the time you’re consuming more than just pure H2O.
So, knowing that we like to dissolve stuff in our water to make it taste a certain way, let’s talk about the differences between sparkling water, seltzer, and club soda.