Photo: Contributed

Diet Pepsi is quietly changing its sweetener ahead of a major rebranding of the soft drink set for next month.

The change comes as PepsiCo Inc. looks to reinvigorate its namesake brands after losing market share to Coca-Cola Co. in recent years.

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 that 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. PepsiCo executives likely don't want to call any attention to the use of artificial sweeteners in the drink either.

When reached for comment Sunday, PepsiCo spokeswoman Andrea Canabal said that Diet Pepsi using the new sweetener mix started hitting shelves in early December. She said the new mix will be more widely available in the coming weeks.

"It's not like a light switch. It'll start appearing as shelf space clears," she said. In January, Canabal said the company is planning a major ad campaign that will include a new logo with a heart and the theme "Love Every Sip."

The sweetener change will not be explicitly communicated in the ads.