(USAToday) - Three times a year, James Cluer, one of about 300 masters of wine in the world, flies to Frankfurt from Napa Valley for a blind tasting of as many as 100 wines.

Over three days, he and other wine experts drink and debate and eventually narrow the list down to three wines. "Sometimes it's surprising who wins," he says. "It's not always the big brand name that comes up on top, but it's the quality."

Those wines eventually end up on Qatar Airways flights, where first and business class passengers have a choice of as many as 12 wines and economy class passengers can choose from five.

At a time when airlines are complaining of high jet fuel prices and charging for any service, there's one amenity they won't cut back on: wine. Airlines across the world buy millions of gallons of wine each year and hire sommeliers and masters of wine to craft elaborate menus.

Most airlines would not disclose how much money they spend on wines, though Qantas says it invests more than $19 million in the Australian wine industry each year. But they do say the investment is worth it because it helps them foster loyalty among their most profitable customers: first class and business class travelers. A good wine list can also get them bragging rights. Airlines are constantly vying for accolades such as the Cellar in the Sky awards by Business Traveller magazine, which Qantas has won for two straight years.