You probably haven't heard his name, but you likely have devoured his creation: two all-beef patties, special sauce, lettuce, cheese, pickles, onions, on a sesame seed bun.

Michael James "Jim" Delligatti, the McDonald's franchisee who created the Big Mac nearly 50 years ago, died Monday at home in Pittsburgh surrounded by his family, family spokeswoman Kerry Ford said Wednesday. Delligatti was 98.

Big Mac creator Michael "Jim" Delligatti attends his 90th birthday party in Canonsburg, Pa., on Aug. 21, 2008. Gene J. Puskar / AP

Until his health trailed off the last couple of years, Delligatti ate at least one 540-calorie Big Mac a week, his son Michael said.

Delligatti's franchise was based in Uniontown, not far from Pittsburgh, when he invented the chain's signature burger in 1967 after deciding customers wanted a bigger sandwich.

Michael Delligatti said McDonald's executives told his father he could experiment with a bigger burger but only using products the restaurant already stocked.

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"He was often asked why he named it the Big Mac, and he said because Big Mc sounded too funny," Delligatti said.

Gene J. Puskar / AP

Jim Delligatti told The Associated Press in 2006 that McDonald's resisted the idea at first because its simple lineup of hamburgers, cheeseburgers, fries and shakes was selling well.

"They figured, why go to something else if (the original menu) was working so well?" Delligatti said then. "But it went over so well in Uniontown that we were allowed to bring it to two stores in Pittsburgh for a couple of weeks."

Demand exploded as Delligatti's sandwich spread to the rest of his 47 stores in Pennsylvania and was added to the chain's national menu in 1968.

McDonald's has sold billions of Big Macs since then, in more than 100 countries. When the burger turned 40, McDonald's estimated it was selling 550 million Big Macs a year, or roughly 17 every second.

"Delligatti was a legendary franchisee within McDonald's system who made a lasting impression on our brand," the Oak Brook, Illinois-based company said Wednesday in a statement. The Big Mac "has become an iconic sandwich enjoyed by many around the world."

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Ann Dugan, a former assistant dean of the University of Pittsburgh's Katz School of Business and an expert on business franchises, said Jim Delligatti's genius was simple: He listened to customers who wanted a bigger burger.

"In franchising, there's always this set playbook and you have to follow it. Jim saw an opportunity to go outside the playbook because he knew the customer," Dugan said. "He persevered and (McDonald's) listened, and the rest is history."