Both sweet and tart, pineapple's distinctive flavor lends a tropical touch to any dish. According to the University of California at Davis, pineapples stop ripening immediately upon removal from the tree, but you can decrease the amount of green visible on a pineapple's exterior by using ethylene gas. Fruits such as apples, nectarines and pears naturally release ethylene gas. When trapped in a paper bag with a pineapple, this gas can change the pineapple's color from green to a yellow on the exterior, making the fruit appear to ripen, but the inside of the fruit will not change in texture or quality, according to the University of California at Davis.
Look for pineapples with bright green leaves, a yellow coloring to the rind and a sweet odor indicating ripeness. Avoid fruit with brown leaves.
Place a whole pineapple into a paper bag with a whole apple.
Fold the top of the bag over and leave at room temperature for one day.
Remove the pineapple, cut and use immediately or refrigerate for up to one week.