Is there something special about this gas in particular that makes it especially suited? Why not use other gasses such as Nitrogen given it’s far more common and already used a lot in the food industry?
In: Chemistry
Gases dissolve in water, but water has a limited capacity to hold any given gas. But carbon dioxide is different, because it doesn’t just dissolve, it *reacts* with water to create carbonic acid. That frees up more room for the water to take up more carbon dioxide, which then reacts to form more acid … and so as a result, **water can hold 100 times more carbon dioxide than it can hold nitrogen or oxygen.**
This is why beer with carbon dioxide in it creates a big fluffy foamy head, while beer with nitrogen gas in it (Guinness for instance) has a small, dense head.
The carbonic acid, just like any other acid, makes the water taste tart, which adds to the flavor of carbonated drinks.
So carbon dioxide is perfect if you want a lot of bubbles and a nice tart flavor. There are a few other gases that react with water instead of just dissolving in it, such as ammonia and hydrogen sulfide, but these are highly poisonous and taste terrible.
It was done a long time naturally because it is a byproduct of yeast fermentation. They produce carbon dioxide as they are anaerobically breaking down sugar.
To continues to be used hardly because it doesn’t really dissolved in water so much as it chemically interacts with water to produce carbonic acid. This makes it very stable under pressure and when the pressure is released it suddenly fizzes up. So it is a good solution for a beverage that might have to be on a shelf for months before opening.
As others have mentioned, CO2 is the traditional means of carbonation as a byproduct of alcoholic yeast fermentation but also lacto fermentation, which is bacterial. Almost all traditional fermented drinks are either one, including the traditional root beers, ginger ales, sarsaparilla etc that inspired modern soda pops.
As a byproduct CO2 is incredibly cheap. Conversely, while nitrogen is plentiful in the atmosphere, it’s more inert and must be harvested by cryogenic fractional distillation, which takes energy, relatively a lot.
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