Ask almost any orchestra's marketing department: New music, they'll tell you, is a tough sell. And a program of unknown composers, with no soloist? Box-office poison.

So how is it that Future Classics -- an uncompromising, all-21st-century concert showcasing scores by the young composers taking part in the Minnesota Orchestra's annual Composer Institute -- has become one of this elite ensemble's signature events?

Aaron Jay Kernis has an answer. For Kernis, a Pulitzer Prize-winner who co-directs the institute with the orchestra's indefatigable Beth Cowart, the composers' compelling life stories, together with their presence onstage, restore a dimension missing from the conventional concert experience, making the musical encounter more immediate.

"It always thrills me to see real connections being made between composers and listeners," said Kernis, the orchestra's new-music adviser. "There's a crackle in the hall. Audiences really start to understand what musical creativity is about; they're actually excited by not knowing what they'll hear next. And that's like an injection of energy for everyone."

Don't trust a composer over 35

This season's hypodermic comes this evening, in a program of recent pieces (including four world premieres) by seven composers ranging in age from 23 to 35, all led by Minnesota Orchestra music director Osmo Vänskä. It was Vänskä who, in 2006, raised the profile of the weeklong institute, which lacked a public component, by adding a culminating concert and conducting it himself. (He also meets privately with each composer.)

"The greater the music director's investment in the new, the greater the audience's enthusiasm," Kernis said. And Vänskä's interest isn't confined to a few days each season: The orchestra reprised one institute piece on a subscription concert and has commissioned an alumnus, Dan Visconti, whose "Overdrive" receives its premiere at Young People's Concerts this week.

The orchestra players, too, have embraced the challenge of learning and playing so much unfamiliar music. "It's hair-raising, like a trip around a racetrack at warp speed," said concertmaster Jorja Fleezanis, one of five senior musicians who lead seminars during the institute (co-presented by the American Composers Forum, with the cooperation of the American Music Center).

"Playing a whole evening with no handlebars is humbling," Fleezanis continued. "All that new stuff puts your marksmanship to the test and calls for a primal interpretive spontaneity. You have to develop a vocabulary for each of the composers -- especially for the revolutionaries, whose struggles have to be felt."

Ted Hearne, one of the composers in this year's cohort (selected by a four-member panel from a nationwide pool of 162 applicants), is a multitasking Yale graduate student who would surely class himself among the revolutionaries. Reached in Houston, where he was preparing a new opera by Michael Gordon (of Bang on a Can fame), he spoke animatedly of taking the orchestra on a journey of exploration: "Some people believe that composers should write so as to minimize the musicians' resistance. I feel that the resistance is where the music really happens. By pushing the players against their training and tapping into their individual sounds, you can produce really powerful results."

Hearne's Future Classics piece, "Patriot," is overtly political, an indictment of "an unconscionable war waged in our name," with a "distorted military vibe" lurking just beneath the musical surface. Justin Merritt's "River of Blood," based on a 1980 massacre of about 600 Salvadoran peasants by U.S.-backed forces, is similarly unflinching. "I often write music that's melodic, friendly and open," says the Texas-born, Indiana-trained composer, who's in his fifth year of teaching at St. Olaf College in Northfield. "But not with this piece. I'm giving it all the emotional weight that the subject demands, and it's absolutely intense. Fasten your seat belts!"

Not all the new scores promise such a strenuous ride. "I don't think my piece [called "Yun"] is hard to listen to," said Taiwanese-born Ming-Hsiu Yen, a University of Michigan graduate student who's both pianist and composer. "I went to Taiwan last summer and played the recording of the premiere for my parents and sister, who aren't musicians. And I think they understood it, though they had different interpretations."

Having your own interpretations -- and discussing them with the composers after the concert -- is not the least of the pleasures offered by Future Classics. The orchestra tunes at 8 p.m.

Larry Fuchsberg writes frequently about music.