TORONTO -- Canadian McDonald's outlets are now serving up new salads featuring an unexpected ingredient from the struggling fast-food giant: Kale.

The world's biggest burger chain, in a battle to reinvent itself, introduced three salads in Canada on Thursday with trendy kale as an ingredient.

The nutrient-rich green has seen a surge in popularity in recent years as health-conscious consumers have eaten leafy kale in salads, smoothies and even baked as chips.

Chris Foong, an analyst with research firm Datassential, said in an email that the number of dining establishments in Canada with kale on the menu increased more than six-fold between 2010 and 2014, to nine per cent of all restaurants across the country.

The vegetable is even referenced in Beyonce's music video for last year's "7/11" single, in which the singer wears a sweater emblazoned with the word "Kale" while dancing on a hotel balcony.

McDonald's is introducing kale at precisely the right time as its moment of pop-culture relevance seems to be at its peak, said Armida Ascano of Toronto-based research firm Trend Hunter.

If the company had released kale options when the vegetable was only popular on food blogs and social media, she said, they would have run the risk of intimidating their existing customers for the sake of impressing those who already choose not to eat at McDonald's.

"This isn't a move to get somebody who's 27 and buys their meat from the local artisan butcher on board with kale," she said. "That person's already on board with kale. This is a move to get the mom who is 44 and loves Beyonce on board with feeding her kids kale."

McDonald's is shifting strategies under new CEO Steve Easterbrook, who took over the top job March 1 and has said he wants to turn the chain into a "modern, progressive burger company."

The company is working to shake its junk-food image as sales at established U.S. locations have declined for six straight quarters. McDonald's American division is running a pilot project of the salads in California.

Embracing kale may seem an odd choice given McDonald's recently mocked the green -- along with soy, quinoa and Greek yogurt -- in an ad that celebrated the Big Mac.

Kathleen Kevany, a social scientist in Dalhousie University's faculty of agriculture who was involved in organizing the first national kale day in 2013, said in an email that McDonald's is known for bringing products that are already popular to a mass market, not innovating new products themselves.

"We can see, with the decline of McDonald's sales in recent years, that other successful products are attracting the attention of consumers," she said. "Kale is one of these successful foods."

Anne Parks, the director of menu management for McDonald's Canada, said the new Greek, Caesar, and harvest garden salads were developed over more than a year of research and focus-group testing.

"We're always trying to meet our customers' needs so the menu is going to change and evolve," she said. "What we're seeing is that people want a balance of choices."

But do they? Not according to one Toronto customer.

"People don't go to McDonald's to eat healthy, they go to McDonald's to eat greasy food," said Hannah Stewart, 24, an occasional patron who still has a fondness for the Happy Meals of her youth.

"I can't see how this will be successful for them; I don't know anyone who's ever even had a McDonald's salad. And no one wants fast-food kale."