I was able to get my hands on mangosteen, a dark purple fruit that is grown in Southeast Asia that is hard to find in the United States. It's got a hard shell on the outside that feels like a very unripe avocado with a very flat and sturdy stem. It's been sitting in my fruit bowl for about a week and the firmness has not changed and I don't smell any fragrance. How do I know if it's ripe enough to eat?
How do I know if a mangosteen is ripe enough to eat?
It is ripe when the rind is dark purple.
The color and feel of the mangosteen will help you know when it's ripe. You’ll know that a mangosteen is ripe when it feels a bit heavy in your hand, the outer peel is smooth, purplish red in color, and yields slightly with gentle pressure from your thumb.
Unripened or over ripened mangosteen will be hard (like, knock-knock hard) on the outside and darker colored peel.
Source: Mangosteen FAQs – FruitStand.com
You can tell if it is ripe when it feels heavy for its size, is smooth and the skin is purple. Also, it will yield slightly to pressure when pressing the side.
You might want to know how to tell if mangosteen is ripe. When it comes to this, you should note that the best way to tell this is by observing the rind of this fruit.
The color for it should start to become purplish and it will eventually become dark purple. Once this happens, the fruit is ripe enough to harvest it and you can then start eating it.
It's difficult to judge mangosteen ripeness from the outside, but as a rule, they don't ripen off the tree, they just rot. (Which is also why mangosteen travel so badly: you can't just pick them raw and ripen them up at the destination.) So it's best to eat them ASAP.
The best method to check ripeness is a practical test: twist off the "crown" of the fruit, place it between your palms with the top facing up, and squeeze gently but firmly, and it will cleanly pop in half if it's ripe. If it goes "squish", it's overripe and likely gone bad. If it's rock hard, it's either unripe or gone bad. And it's commonly for a single batch bought at the same time to have fruit in all three stages.