Not only the immature fruits of the bitter melon taste bitter, even the ripe fruits have a subtle bitterness – at least in the ripening skin. This has a soft, brittle consistency and tastes quite a bit watery in addition to the slight bitterness. The red tissue, which encloses the poisonous seeds, tastes very sweet.
There is much dispute about the edibility of ripe fruits. The immature bitter melons, which are very frequently consumed in Asia, can cause problems in too large quantities because of the bitter substances contained. Ripe fruits taste not so good, especially not boiled (too watery), and they disintegrate easily (badly tradable). To me, the red aril is a candy, which however must be enjoyed with caution because of the poisonous seeds. (More information: “Picking Edible and Medicinal Plants: Exotic” Apples “and” Pears “, Wilderness & Environmental Medicine, Volume 27, Issue 1, March 2016, Pages 168-170)
There are 2 varieties with different-looking fruits: the Indian variety has fruits with tooth-like outgrowths, which is the most common. The Chinese variety is wavily wrinkled and almost even.
The bitter melon is spread pantropical, their home are however the tropics of Asia. The plant is an invasive neophyte in many regions, but is also cultivated worldwide as a food and medicinal plant.