Part of the show Stars, Cosmology and the Beginning of the Universe
Ricardo in Brazil asked:
Why is it that we like drinks with gas, like beer or coke? If we drink these beverages without it, they taste bad, but gas is tasteless. What effect do bubbles have? Is it just down to the sensation?
I think it's the texture. The bubbles in the drink actually make very little contribution to the acidity. Acids generally taste a little bit lemony. However, if you look at drinks like Coca Cola for example, they're so acidic, they'll rot your teeth away. In fact, Coca Cola is on the same level as stomach acid, so the carbonic acid effect from the dissolved carbon dioxide makes very little difference. What the carbon dioxide does do is make a very interesting sensation in your mouth. Firstly, if you think of a glass, you often see a stream of bubbles all coming from one place. This is an imperfection in the glass that makes it very easy for bubbles to form, and is called a nucleation point. Your tongue has hundreds of tiny imperfections, and therefore nucleation points. This makes hundreds of tiny bubbles start pinging off all over your tongue. This is like having your tongue massaged by bubbles. I think this added dimension is what makes fizzy drinks taste good.