(AP) — Delta Air Line's master sommelier Andrea Robinson opened up bottle after bottle of white and red wine from France, Italy, Australia, the U.S. and other parts of the world. As she tasted them Monday, a blue bucket sat on the table next to her. It was there so she could spit out each sip, ensuring she didn't get tipsy and could distinguish between the different wines. By the time she's done in the next few days, Robinson will have tasted and smelled roughly 2,000 bottles. The delicate work of a sommelier has become more important as U.S. airlines fight for premium passengers willing to shell out up to thousands of dollars to fly business class on international and transcontinental flights. The idea isn't to make money on the wine — the passengers in those seats drink for free — but rather to keep those customers coming back and encourage their well-heeled friends and co-workers to join them.