What is chewing gum made of?

Food writer and researcher Swetha Sivakumar is demystifying one ingredient every week at HT Wknd. This week: Chewing gum. What goes into chewing gum? What makes it so sticky, what makes it so stretchy? Will we ever know all that goes into a stick of gum? And why are biodegradable chewing gums so rare? Find out.