We had hachiyas on the weekend, and while I actually prefer the flavor of hachiyas slightly, they're astringent varieties, and so are a bit riskier. They have to be totally ripe before you eat them, or the inside of your mouth will turn to nasty, nasty fuzz. Not for the faint of heart. But if you are bold, daring, and willing to wait until they are ripe, they are delicious.
"The heart-shaped Hachiya is the most common variety of astringent persimmon. Astringent persimmons contain very high levels of soluble tannins and are unpalatably astringent (or "furry" tasting) if eaten before completely softened. However, the sweet, delicate flavor of fully ripened persimmons of varieties that are astringent when unripe, is particularly relished. The astringency of tannins is removed in various ways. Examples include ripening by exposure to light for several days, and wrapping the fruit in paper (probably because this increases the ethylene concentration of the surrounding air). Ethylene ripening can be increased in reliability and evenness, and the process can be greatly accelerated, by adding ethylene gas to the atmosphere in which the fruit are stored. For domestic purposes the most convenient and effective process is to store the ripening persimmons in a clean, dry container together with other varieties of fruit that give off particularly large quantities of ethylene while they are ripening; apples and related fruits such as pears are effective, and so are bananas and several others. Other chemicals are used commercially in artificially ripening persimmons or delaying their ripening. Examples include alcohol and carbon dioxide which change tannin into the insoluble form. Such bletting processes sometimes are jumpstarted by exposing the fruit to cold or frost. The resultant cell damage stimulates the release of ethylene, which promotes cellular wall breakdown.
One traditional misconception is that persimmons are to be ripened till rotten. This is a confusion of the processes of controlled ripening with the processes of decay, possibly arising from problems of translation from Asiatic languages onto English. Rotting is the action of microorganisms such as fungi, and rotting persimmons are no better than any other rotting fruit. Sound persimmons should be ripened till they are fully soft, except that the carpels still might be softly chewy. At that stage the skin might be splitting and the calyx can easily be plucked out of the fruit before serving, which often is a good sign that the soft fruit is ready to eat."