NEW YORK — Diet Pepsi is quietly changing its sweetener, with the goal of helping the soda maintain its taste longer.

Cans of Diet Pepsi around the country now list a mix of two artificial sweeteners, a pairing that is commonly found in newer diet sodas. Previously, Diet Pepsi used only aspartame, which is sensitive to heat and breaks down more easily.

This summer, PepsiCo had declined to say whether it would go ahead with such a change after reports surfaced it was testing the new sweeteners. Although the switch is only intended to help prevent the taste from degrading over time, companies are often sensitive to public perceptions that they might be tinkering with major brands.