A coffee producer weighs beans at a Costa Rican plantation. (Photo: Reuters via WSJ) By Leslie Josephs Wall Street Journal December 16, 2010 NEW YORK—The exchange that oversees the world's most actively traded coffee futures has answered a wake-up call. Responding to a growing buzz that its stockpiles of arabica coffee include beans far past their prime, IntercontinentalExchange Inc. last week said it will for the first time prohibit beans too old to make good coffee from being delivered against the contract. Coffee stockpiles have dwindled as bad weather has slashed consecutive harvests in some countries in Central America, as well as in Colombia, the world's largest producer of the prized, mild-washed arabica beans. ICE's stockpile of certified coffee has plunged 44% since the start of the year The ICE announced last week that it will include arabica beans from Brazil, the world's top coffee producer, on the list of coffees that can be delivered against the...