Who doesn’t love a little outdoor mess from time to time? Pour mint Mentos into a 2 liter bottle of diet cola, then stand back! The formation of the foam is caused by the potassium benzoate, aspartame and CO2 gas contained in the diet cola mixed with the gelatin and gum arabic ingredients of the Mentos. Mint Mentos work best as the surface is covered with small holes, which increases the area of reaction.