McDonald's (MCD) has filed a trademark registration related to selling ground and whole-bean coffee. The company isn't commenting on the issue, but the intent is obvious: McDonald's may soon intensify its competition with Starbucks (SBUX) and Dunkin' Brands (DNKN).

It's unclear how this will play out. McDonald's might sell bagged coffee at its restaurants like Starbucks does. Or it might sell coffee on supermarket shelves. Perhaps McDonald's is looking at producing coffee pods for single-cup machines like the Keurig brewers from Green Mountain Coffee Roasters (GMCR). There are so many possibilities.

Dunkin' Donuts has seen strong sales of bagged coffees, The Wall Street Journal reports.

The move makes sense. Coffee has been a bright spot for McDonald's since the burger chain started the McCafé concept five years ago. And Starbucks has estimated that packaged coffee is a $5.6 billion business in the U.S., the Journal reported, with 58% of American adults drinking coffee.

McDonald's said in 2010 that coffee drinks had grown to more than 6% of its U.S. sales, up from 2% in 2004. Assuming the percentage has increased since then, McCafé is becoming a key part of the business.

"We do see coffee as a point of leverage and growth for us," McDonald's CEO Don Thompson said in 2010 when he was the company's president and chief operating officer.

McDonald's downplayed the trademark filing when contacted by BurgerBusiness, saying it registers a lot of trademarks.

McDonald's enjoys some very loyal coffee drinkers. A survey last year reported by The Journal found that only 29% of McDonald's coffee drinkers also visit Dunkin' Donuts and Starbucks. But 53% of Dunkin' Donuts and Starbucks customers will "roam" to other chains.

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