seconds. Process 30 seconds. Transfer puree to mixing bowl. Repeat, processing remaining pineapple with remaining sugar syrup. Combine all of puree. Stir in lemon juice and vodka. Transfer pineapple mixture to 2 shallow baking pans, dividing evenly. Cover with plastic and freeze until half frozen. Process each batch of partially frozen sorbet mixture in food processor 1 minute, stopping once to scrape down mixture. Return to pans, cover and freeze until 0.75 firm. Process each batch once again 1 minute. Return to freezer until 0.75 firm, then process another 2 minutes. Pack into airtight container and freeze until firm enough to scoop or spoon, 4 to 6 hours.