Until recently, Diet Pepsi contained only one artificial sweetener, aspartame. The problem is, heat can cause aspartame to break down, changing the taste. The addition of a new chemical, acesulfame potassium, aims to stop this problem — the second sweetener stabilizes the overall formula.
Acesulfame potassium is apparently a common ingredient in many sweetened products, typically added quietly with customers never noticing a difference in taste.
You shouldn’t necessarily expect to see the new ingredient listed on cans of Diet Pepsi right away. The first drinks with the new formula began shipping in early December, but the newer version will only appear when old product needs to be restocked. Andrea Canabal, spokeswoman for PepsiCo, told USA Today, “It’s not like a light switch. It’ll start appearing as shelf space clears.”
Diet Pepsi hopes to gain sales at the expense of Diet Coke, the drink’s main rival. Currently, Diet Coke uses only a single sweetener.