To eat a mangosteen, first use a knife to cut the purple rind around the fruit's center, being careful to not cut the soft fruit inside. Next, twist the top and bottom halves of the cut rind to open the mangosteen. Finally, scoop out the soft, white segments and eat.
The seeds and rind of the mangosteen are quite bitter and should not be eaten. If you are unable to eat a ripe mangosteen right away, place it in the refrigerator. As the fruit ages, the rind dries out and hardens, and the seeds inside the fruit may turn brown.