William Entenmann, an immigrant from Stuttgart, Germany, first established the bakery in Brooklyn in 1898, delivering cakes in a horse-drawn wagon. When his son began suffering from rheumatic fever, he moved the store to the healing air of Bay Shore, according to a company website. Morgans and Vanderbilts enjoyed a slice now and then, and Frank Sinatra, in the 1950s, placed weekly orders for crumb coffeecake.

Image Bill Hayduk, 50, has fond memories of his mother’s picking up its pastries for breakfast. Credit... Bryan Thomas for The New York Times

The loss greatly reduces the brand’s ties to its traditional home, a presence so sturdy that much of Bay Shore’s Fifth Avenue is named Entenmann’s Way and events like Entenmann’s Great South Bay Run brandish its label.

“It will not have the economic impact it once had because it will not have the jobs it once had,” said Lawrence Levy, the executive dean of the National Center for Suburban Studies at Hofstra University. A spokesman for Entenmann’s said that the plant once employed 1,500 workers. The challenge for the company now, Mr. Levy said, is “to make Long Islanders feel it’s still a Long Island company.”

A Long Islander for most of his 64 years, Mr. Levy recalled the culinary clout Entenmann’s wielded.

“Entenmann’s products were ubiquitous in part because they were made here and they were considered a step above,” he said. “If you wanted to show off before relatives from Queens and Brooklyn who came out for barbecue or brunch, you bought Entenmann’s.”

The company, which has headquarters in Horsham, Pa., near Philadelphia, has been owned since 2002 by Bimbo Bakeries USA, which bills itself as the nation’s largest baking company and owns such venerable bread and pastry brands as Arnold, Freihofer’s, Sara Lee, Stroehmann and Thomas’. It is a division of Grupo Bimbo, a Mexican company, which operates in 19 countries with more than 124,000 employees.