triangle K - grape juice in ingredients

Question

minute maid orange passion ingredients: oranges, grape and passionfruit juices from concentrate, guava juice, less than 1% of each: ascorbic acid, tricalcium phosphate and calcium lactate, natural flavors. 1 K? this is the first time i have ever seen a triangle K on any product that contains grape juice. 2 is there a difference if it is grape juice or from concentrate?? 3 what is concentrate anyway?