In the United States, the FDA allows 46 different chemicals under the umbrella of "gum base".
A bubble gum base is formulated with the ability to blow bubbles; it contains higher levels of elastomers or higher molecular weight polymers for this purpose.
Gum bases for antacid use calcium carbonate as a filler, while gum bases for acid flavored gum use talc as a filler, since acids can react with calcium carbonate to produce carbon dioxide gas, which is undesirable.
Wrigley Jr. Company are studying the possibility of making gum base with biodegradable zein (corn protein).
Formulation and Production of Chewing and Bubble Gum, edited by Doug Fritz, pp 93–118, Olivias's Publications Ltd, London, UK, 2006