Christopher Kimball, the bow-tied cooking guru who started the popular Cook’s Illustrated magazine and created a foodie media empire, is leaving the Brookline company amid a management shake-up, raising questions about the future of a venture so closely tied to its star founder.
Kimball will remain a minority owner and will continue to host his TV shows, “America’s Test Kitchen” and “Cook’s Country,’’ through the 2016 season. But his departure marks the end of a chapter for a local company with a national audience, as it looks to expand its offerings and hang on to a loyal following of cooking aficionados without its central personality.
“I think it will be extremely difficult initially, because Chris is the face of that company. His personality is what defines the spirit of the show,’’ said Gordon Hamersley, the longtime Boston chef whose former South End restaurant was a frequent dining destination for Kimball.
Hamersley called Kimball “the iconic leader of that cult over there. It’s his persnickety . . . wonderful personality that defines that show.” He predicted the company, which employs 180 people, will “survive, but it will go through an abrupt transition.”
News that changes were afoot at the company first became public in September, when the board named a new chief executive, David Nussbaum, a one-time reporter turned online media and e-commerce executive. The board has been negotiating with Kimball since then on a future role for him at the company, but talks fell apart in recent weeks, according to people briefed on the conversations.
While Kimball “will remain a minority owner of the company, he will no longer play a role” at America’s Test Kitchen, Nussbaum wrote in a letter to employees Monday.
Kimball, 64, may be planning to start a new venture, according to people who know him. He declined to comment. Kimball’s wife, Melissa Baldino, a TV producer at the company, also is expected to leave, according to two people with knowledge of the situation.
In an interview, Nussbaum credited Kimball with being the visionary behind the business but he downplayed concerns that the brand will be diluted without him. Nussbaum said the company — often referred to as simply ATK — would continue the tireless recipe testing that helps draw its 1.2 million magazine subscribers, as well as audiences online, on television, and on radio.
“The owners are very committed to investing in the business and holding it for the long term,’’ he said. “There’s nothing broken here — that’s the beauty of it.”
Kimball is the face of “America’s Test Kitchen,” the most popular cooking TV show on public television nationwide, and an exacting specialist on everything from how to bake the perfect chicken to the right skillet to use in browning butter for cookie batter.
While admired by chefs and cooking colleagues, he is also known to be a demanding boss, a perfectionist who would taste only the most successful concoctions coming out of his test kitchen, after employees weeded out lesser versions.
Cook’s Illustrated has a large paid subscriber base of 900,000; Cook’s Country has 300,000 subscribers. Both magazines come out six times a year. There are also 425,000 Web subscribers, the company said, along with wide followings on TV and radio.
Kimball has built that loyal following in part through avoiding advertising, in print and online. While the company is private and does not release its sales or profits, it has more than $40 million in annual revenue, according to published estimates.
Some close observers of the magazines said introducing advertising or sponsorships could alienate customers. But Nussbaum said there are no plans to start using advertising to raise revenue.
“We’re not changing those policies,’’ he said.
Ming Tsai, chef and owner of Boston-area restaurants Blue Ginger and Blue Dragon, and host and executive producer of “Simply Ming” on PBS, said Kimball’s approach worked.
“He did something that still very few have copied: He said no to advertising. We’re going to talk about food, and techniques, and I don’t want to be influenced by advertisers. He actually could test 10 food processors and since Cuisinart wasn’t advertising, he could have a completely unbiased opinion,’’ Tsai said.
He also suggested that it’s inevitable the company will change without Kimball.
“The company is him. Cook’s Illustrated is him. ‘America’s Test Kitchen’ is him,’’ Tsai said.
Kimball is one of four individual owners who hold stakes in the company, including his cofounder, investor Eliot Wadsworth.
Other partners in ATK’s holding company, Boston Common Press, are George P. Denny III and John D. Halpern, former Bain & Co. consulting executives. Kimball’s ex-wife also is an investor, among other family members.
Kimball first dove into publishing in 1980, launching a magazine called Cook’s from his Connecticut home when he was just 29. He sold that publication and later launched others, ultimately returning to cooking as his subject of choice.
In the letter to employees Monday, Nussbaum wrote, “For some time, the board, senior management and I have been discussing the continued growth and evolution of the company,” while staying focused on research and the home cook.
The company, he said, is “financially strong and well-positioned” for a new era. It plans to add 25 new hires in 2016 and invest in its facilities. Last week, it announced a new position of chief digital officer, and announced the hire of a new chief financial officer and head of human resources.
In the interview, Nussbaum said America’s Test Kitchen would strive to honor Kimball’s vision. But, he said, “Nothing stays the same forever. It can’t.”Sheryl Julian and Devra First of the Globe staff contributed to this report. Beth Healy can be reached at email@example.com. Follow her on Twitter @HealyBeth.