On Sept. 8, Christopher Kimball will begin his nationwide “Culinary Mystery Tour” right here in Portland – a live event intended to help launch his new multimedia food venture, Milk Street Kitchen.

The founder and until last year face of America’s Test Kitchen says the show will be heavily oriented toward the audience, meaning lots of taste tests and Q & A’s, along with whipping egg whites, playing with Jell-O and maybe, Kimball coyly suggests, just maybe, one of the silly costumes he was known to wear on his former “America’s Test Kitchen” TV show. (Remember Carmen Miranda? The bright banana? The giant cut of steak?)

Portland is the smallest city on Kimball’s tour, which will mostly go to big urban centers such as New York, Chicago, San Francisco and Seattle. So why Portland? Perhaps it’s because Kimball visits here a lot during the summer – he lives in Boston and his in-laws live just north of Portland. He recently tweeted photos of the fish sandwich at Eventide Oyster Co. and of the apricot scone at Standard Baking Co. He’s also eaten at Hugo’s and Central Provisions.

“There are so many places (in Portland) that are wonderful,” Kimball said. The restaurant scene in the city is “actually almost better than Boston in many ways. It’s more interesting. Boston has some great food, but I’ve just found the food (in Portland) to be really amazing.”

Kimball developed America’s Test Kitchen into a media empire, which today encompasses two TV shows, two magazines, a radio show, podcast, websites, online cooking school and a robust cookbook division. Last year, he surprised home cooks everywhere when after nearly 25 years he abruptly left the business that had made him a household name. He is starting over with Milk Street Kitchen. (His final episodes as host of the “America’s Test Kitchen” and “Cook’s Country” TV shows will air through the end of 2016.)

America’s Test Kitchen is known for its rigorous testing of recipes and techniques. The 65-year-old Kimball jokes that he stood on a TV set for 25 years watching someone chop onions, trying to look interested. Milk Street Kitchen is the result of that bored TV host’s own personal transformation in the kitchen, when he started experimenting outside his comfort zone and stopped being handcuffed by technique.

Milk Street Kitchen, another multimedia empire in the making, is based on the idea that home cooking needs an infusion of bolder flavors, fresh ideas and new ingredients from around the globe; the concept is quite different from his original idea for America’s Test Kitchen, which focused on the most traditional of American food, such as apple pie and pot roast. Such changes are already happening in supermarkets, cookbooks, food TV and restaurants, Kimball (and anyone with a pulse) has observed. Just as fashion and music have been inspired by a variety of cultures, Kimball says, other cultures and cuisines are being opened up to the American cook through what he calls “the new home cooking.” It’s not, he says, just about cooking ethnic foods. Think Thai-style coleslaw or Asian chicken noodle soup.

“This is not really about me cooking Thai food or Cantonese or Moroccan food,” Kimball said. “It’s just about finding techniques and combinations of flavors, or ways of thinking about cooking to expand the repertoire. I’m not trying to cook somebody else’s food. Here’s the difference: Instead of going in the kitchen and taking an oatmeal cookie and making it 45 times, I’m starting somewhere else in the world to learn from somebody and listen to what they have to say and trying to figure out how I can adapt that back here.”

Kimball said his own cooking started to change three or four years ago, when he started reading and cooking from a lot of different books “and I realized I didn’t know as much about cooking as I thought I did.” One of his biggest inspirations was the work of Yotam Ottolenghi, author of “Plenty” and “Jerusalem” (the latter with Sami Tamimi), known for blending ideas and ingredients from different cultures. Kimball also got lots of practical advice from people around the world he had on his radio show. “I started hanging out with some people who cook this way as well,” he said, “and I just found the food cleaner, brighter, bigger flavors, and just a lot more interesting.”

American food, for example, doesn’t “do bitter” well, except for maybe some Southern cooking with greens, “but the rest of the world loves bitter,” Kimball said. Bakers and pastry chefs are experimenting with salty and sour tastes in their desserts, he added. Earlier this summer, Kimball traveled to London to film one of his first Milk Street Kitchen TV shows with Claire Ptak of Violet Bakery.

“She’s thinking about not just sweet, but sweet, salty, bitter,” Kimball said. “She uses rye flour, which has got kind of a bitter note to it. When you think about it that way, her baked goods are much more interesting because they are more complex. They’re not harder to do, they’re just more interesting.”

Maine food writer Nancy Harmon Jenkins says she has a lot of respect for what Kimball did with Cook’s Illustrated. He wasn’t driven by trends, and was rigorous about not accepting any advertising.

“I think the death of the food media in this country has been advertising,” she said, “and he stayed out of that completely.”

She’s more skeptical about Kimball’s desire to bring bolder flavors to American food. While there is “a real resistance” in American kitchens to any cuisine that is not familiar to home cooks, she said, many of those bolder flavors are already here – it all depends on how you define “American cuisine.”

“You can’t say American food is meat and two vegetables on a plate, and one of those vegetables is potatoes,” Jenkins said. “You just can’t do that any longer. German-American cuisine is full of sour flavors. It’s a very reductive way to approach American food, I think.”

Like America’s Test Kitchen, Milk Street Kitchen will have a public television show, magazines, cookbooks and a digital platform. Unlike America’s Test Kitchen, it will also have a hands-on cooking school, in a building at 177 Milk St. in Boston that is undergoing a million-dollar renovation.

If the setups seem similar, Kimball insists they aren’t. There’s “nothing inherently competitive” about having media properties, he said, adding that it’s tough to be in food these days without having a presence on television.

“I wouldn’t be interested in doing this if it were just more of the same,” he said. “I really am excited about this. I think the editorial gestalt or idea behind it is quite different. It’s not a test kitchen. We’re not making a recipe 45 times. We’re not testing cookware. We’re not rating food products. We’re not doing the whole Consumer Reports thing. I think (America’s Test Kitchen) does a great job of that, and I have nothing more to add to that.” While America’s Test Kitchen today has a couple hundred employees, Kimball said, Milk Street won’t ever have more than 50, among them his wife Melissa Baldino, who used to produce the television shows at America’s Test Kitchen.

“We want to keep it focused and very personal so I can get my hands on stuff and get closer to the creative part of the business. People here might argue whether that’s a good thing or a really bad thing,” he said, laughing.

J.M. Hirsch, former food writer for the Associated Press, is one well-known name (to regular readers of American newspaper food coverage in the last 15 years), who is joining the team as editorial director. Kimball said the company will announce another couple of “notables” joining the team in the fall.

Asked to assess what the last year has been like, Kimball noted that in just eight months he’s raised money for Milk Street Kitchen, put together a staff, supervised a $1 million renovation and started work on a new TV show, magazine, radio show and cooking school.

Beats retirement.

“You get to a point in life where you think it’s going to be one thing, and it’s something totally different,” Kimball said. “Then you realize, actually, it’s the best thing that’s ever happened to you.”