Preparation Working in 3 batches, purée pineapples, banana, and juices in a blender until very smooth. Transfer as puréed to a large pitcher. (If pineapple is particularly fibrous, pour through a medium-mesh sieve, pressing hard on and then discarding solids.) Stir in rum. Chill, covered, until cold, about 1 hour. Stir again (or blend for a frothier texture) just before serving. Cooks' note:Batido can be made 1 day ahead and chilled, covered.
Preparation Working in 3 batches, purée pineapples, banana, and juices in a blender until very smooth. Transfer as puréed to a large pitcher. (If pineapple is particularly fibrous, pour through a medium-mesh sieve, pressing hard on and then discarding solids.) Stir in rum. Chill, covered, until cold, about 1 hour. Stir again (or blend for a frothier texture) just before serving. Cooks' note:Batido can be made 1 day ahead and chilled, covered.