(Bloomberg News) When British Prime Minister David Cameron visited President Barack Obama in March, one detail remained bottled up: the labels on the wines the White House poured at the state dinner.

For Obama's first three state dinners, honoring the leaders of India, Mexico and China, the White House released the name, year and appellation of wines-all-American-paired with each course.

Part of a tradition observed by previous presidents, including George W. Bush, that disclosure stopped after Obama's dinner last year for Chinese President Hu Jintao. One of the wines served on January 19, 2011, was a top-rated 2005 Cabernet Sauvignon from Washington state that originally sold for $115 a bottle and went for as much as $399 by the time of the dinner. The price the White House paid per bottle was not made public.

At the next state dinner, on June 7, 2011, for German Chancellor Angela Merkel, the menu made public by the White House didn't include details on the wines.

"An American wine will be paired with each course," stated a note at the bottom of the menu released by the White House. So went as well the menu released for the Korean state dinner honoring President Lee Myung-Bak on October 13.

Tyler Colman, who writes the Dr. Vino wine blog and teaches at New York University, says that the shift in menu protocol may reflect political considerations given the sluggish U.S. economy.

"They're probably sensitive to displays of wealth at a time when the economy is not firing on all cylinders," says Colman, whose blog had noted the absence of wines on the German state dinner menu the White House released.

No 'Picnic'
Still, keeping the wine list under wraps undercuts promotion of U.S. winemakers at a time when markets in developing nations such as China have potential to be "really hot" for U.S. labels because of the rising middle- and upper-income classes, he says.

A state dinner "isn't a picnic or casual get-together," and it's justifiable from diplomatic and trade standpoints for the White House to spend money to showcase fine American wines, Colman says.

Dorothy Gaiter, wine and food editor for the quarterly France Magazine and a former wine columnist for The Wall Street Journal, says Obama was private about his wine preferences before his election.