From the Davis Enterprise, December 27, 2007
We get questions....
I've heard there is a way to pick persimmons and ripen them so they aren't astringent.
Of the dozens of Oriental persimmon varieties, two are commonly grown in California. Fuyu persimmons are flattened on the bottom and are non-astringent. They can be eaten as soon as they turn orange (November), having a mild, sweet flavor and a texture firm enough to munch like an apple or add to fruit salad. They also dry nicely, sliced thin and layered in a fruit dehydrator for a few hours. Dip the slices in melted chocolate for an elegant touch.
Hachiya persimmons are elongated and have a point on the bottom of the fruit. They turn color in November but aren't edible until December. Hachiya and other astringent persimmon varieties, including the native American species, are famous for their astringency when under-ripe, and for their gelatinous texture when ripe. Many people are put off by the gooshy ripe fruit, but Hachiya has a richer flavor and is more prized for cooking.
Astringency in persimmons is caused by tannins, the same chemicals that make tea, red wine, and unripe bananas and peaches cause your mouth to pucker. Tannins cause the surface of your tongue and mouth to constrict and stop salivating: 'it will drawe a mans mouth awrie with much torment,' said Captain John Smith upon tasting the American 'putchamin' in Virginia. Mmmm. Yet fully ripe, with the flesh nearly liquid, they are described as luscious and honey-like.
The USDA tried over a number of years to introduce persimmons to growers and consumers, and sought to overcome the astringency and mushiness of the fruit in order to broaden its appeal. Observing the process of ripening employed in Japan and China, they saw the hard, unripe fruit:
--immersed in a mix of water and lime for several days.
--sealed in a covered earthenware jar with a burning stick of incense for a day or two.
--buried in mud for several days.
--packed in sake casks just after the sake was drawn off, immediately sealed air tight.
Each of these techniques left the fruit firm, ripe, and non-astringent.