Kyle Ketelsen and Keri Alkema -- who will sing the leads in Minnesota Opera's "Anna Bolena" -- offer an interesting study in contrasts.

During a lunch break from rehearsal last week, he had sweet potato soup, a romaine salad (checking to make sure there were no onions or cucumbers) and a dark beer. She was fine with iced tea.

Ketelsen has a Midwest home with a wife and two kids; Alkema and her husband live out of a suitcase and two storage units. If he couldn't sing opera, he doesn't know what he'd do. She ticks off a half-dozen other paths if calamity struck her singing career.

She knows every detail of the story of King Henry VIII, his place in history and his ruthless relationship with his second wife, Anne Boleyn. He came to Minneapolis with a working knowledge of "I'm Henery the Eighth, I Am" by Herman's Hermits.

What they share is a fresh look at the demanding opera that opens Saturday at the Ordway Center in St. Paul. "Anna Bolena" completes Donizetti's Tudor trilogy for Minnesota Opera. "Roberto Devereux" started the series in 2010 and "Maria Stuarda" was produced last year. "Anna Bolena" actually casts the story back in history. Anne Boleyn bore Queen Elizabeth I, the key role in both of the other operas.

Ketelsen, as Henry, and Alkema as the title character make their debuts in the roles.

"There are fewer preconceptions in a new production," Ketelsen said. "It can be a security blanket if you've done it before, but Kevin [director Newbury] knows what's going on."

Alkema expressed a fearless confidence to tackle a role that Joan Sutherland declared one of the most difficult in the repertory. The current queen of all things opera, Anna Netrebko, sang the role one year ago in the Metropolitan Opera's first production. Her reviews were uneven, demonstrating just how demanding the part is.

"It's not so much the individual pieces as it is the stamina," Alkema said. "I wish I could go back to Maria Callas and ask, 'How did you pace yourself out?' The last aria is 20 minutes long."

Callas' 1957 performance at La Scala is considered a career achievement. Alkema spent hours listening to the legendary soprano, picking up a few tips. Callas left out many of the high notes, for example, to preserve her energy. Netrebko, too, Alkema said, didn't go for the high E-flats.

"You listen for what cuts they took because the opera is so big," Alkema said. "Where did they save themselves; how do lighter voices handle the lower registers?"

Different kind of role

King Henry is not a standard bel canto bass role.

"He's not an old man, or a villain, or Friar Lawrence," Ketelsen said. "He's still youthful, virile and that should show in his voice."

Ketelsen sang Mephistopheles in "Faust" at the Minnesota Opera in 2009 and made his debut here in the title role of "Don Giovanni" in 2006. He made his Met debut last season in "Billy Budd" and as Leporello in "Giovanni."

A native Iowan who lives in Madison, Wis., Ketelsen is among the new breed of male leads: tall, square-jawed, lean and confident. In 2009, he was featured on barihunks.blogspot.com, a website celebrating "the sexiest baritone hunks from opera."

Henry, full of youthful caprice -- like a "spoiled brat" -- is more flattering than other bel canto roles, Ketelsen said.

The third character in the "Anna Bolena" love triangle is Jane Seymour, Boleyn's lady-in-waiting in more ways than one. Henry was eager to dispatch Anne, who failed to produce a male heir, and to marry Jane Seymour. The role is sung by Lauren McNeese in the Minnesota production.

McNeese and Alkema have known each other since they met at Sante Fe Opera in 2004. This is their first time together on stage. "I feel bad for Jane," said Alkema, which is a little odd seeing as Jane wins the king and Anne loses her head. "She's a conflicted character."

As the lunch check arrived, Ketelsen reached for one of four tiny complimentary truffles in a dish. He tried to get Alkema to take hers.

"No chocolate," she said. "I have to sing this afternoon."

Graydon Royce • 612-673-7299