Why do twizzlers make Soda fizzle?

Question

Me and my friends like to use twizzlers as straws, but everytime we do our soda fizzles up and its strange. We'd like to know why :)

Answer 1

Soda is made up of basically four things; sweetener, flavoring, water and preservatives.  Once the soda is mixed, it is pressurized heavily with CO2 gas.

Gasses want to expand naturally, but when pressurized into the soda mixture, the water severely restricts this.  Water molecules are strongly attractive to each other, so it takes a great deal of force for the gas to be able to expand.  This is why you only see small bubbles release from a glass of soda.  There are 2 factors that are causing the foaming/bubbling of the soda when you put your "straw" in.

Twizzlers candies contain glycerin and gum arabic, both of which are minor surfactants; that is they chemically reduce the "surface tension" of water by weakening the bonds between water molecules. So, by introducing these chemicals into the soda, you've made it easier for the CO2 to expand.

Now that it is easier for the CO2 to expand, the bubbles need a place to form, called a nucleation site.  Despite their smooth appearance, the licorice has many small pits and bumps that act as nucleation sites for the now freer to expand CO2.

The combination of the surfactants and the nucleation sites provided by the candy is what cause the foamy reaction of the soda.  This is the same type of principle which causes the "explosion" when Mentos candies are put into soda, with some physical distinctions being the difference between a small fizz (the Twizzler) or a big explosion (the Mentos).