Japanese Persimmon

''Diospyros kaki'', the Oriental persimmon, Chinese persimmon, Japanese persimmon or kaki persimmon, is the most widely cultivated species of the genus '' Diospyros''. Although its first botanical description was not published until 1780,Published in ''Nova Acta Soc. Sc. Upsal.'' iii. 208, author Carl Peter Thunberg, hunb.(1780); later in ''Fl. Jap.'' 157, author Thunb. (1784). ''D. kaki'' is among the oldest cultivated plants, having been in use in China for more than 2000 years.

Names

Whether the species was first described by Carl Peter Thunberg or Carl Linnaeus the Younger is disputed. The scientific name ''Diospyros kaki'' L. f. may be used erroneously for this plant. However, ''Diospyros kaki'' L. f., published in 1781, is a later homonym of ''Diospyros kaki'' Thunb., published in 1780. So the name ''Diospyros kaki'' L. f. is taxonomically illegitimate and not accepted.

It is called ''shi'' (柿) in Chinese, ''kaki'' (柿) in Japanese, ''gam'' (감) in Korean, kesemek in Indonesia and haluwabed (हलुवाबेद) in Nepali.

Tree

Similar in shape to an apple tree, the ''kaki'' tree reaches a size of up to . Its deciduous leaves are medium to dark green, broadly lanceolate, stiff and equally wide as long. Blooming from May to June, the trees are typically either male or female, but some produce both types of flowers. Furthermore, the sexual expression of a tree may vary from year to year. Unusually, the ''kaki'' fruits ripen when the leaves have mostly fallen off the tree, typically in October and November. (Northern Hemisphere)

Flower

''Kaki'' trees typically do not bear until they are 3 to 6 years old. The flowers are wide and appear in late spring or early summer, depending on variety and growing area. The tubular flowers have a creamy white color. Female flowers grow singly, while male flowers sometimes may have a pink tint and tend to appear in clusters of three. Diospyros kaki is typically a dioecious species, which means that trees are either male or female, but some cultivated varieties are monoecious. In that case both male and female, and even perfect (male+female), flowers can be found on the same tree. The flowers have four crown-shaped sepals and four petals that form a large calyx.

All varieties (parthenocarpic) will produce seedless fruit in the absence of pollination, but their pollinated flowers will produce more fruit riddled with seeds. Kaki typically suffers very important fruit drop. The first flush of fruit drop happens shortly after flowering, when +/- 50% of the fruit will drop. The second flush happens in August when again many fruits will drop. After this, the rest of the fruit will usually stay on the tree and mature. Fruit drop depends on climatic conditions and water availability. Pollination is not necessary for fruit set, but it may help reduce fruit drop after averse climatic conditions or drought periods.

Fruit

The persimmon is an edible sweet, slightly tangy fruit with a soft to occasionally fibrous texture. This species, native to China, is deciduous, with broad, stiff leaves. It was first cultivated in China more than 2000 years ago, and introduced to Japan in the 7th century and to Korea in the 14th century. It was later introduced to California and southern Europe in the 19th century, to Brazil in the 1890s. Numerous cultivars have been selected, and one variety is ''Diospyros kaki'' var. ''sylvestris'' Makino.

When ripe, the fruit comprises thick pulpy jelly encased in a waxy thin-skinned shell.
The spherical to oval fruit, bearing the indented stem and four sepals, can weigh up to . The smooth, shiny, thin shell ranges in shade from yellow to red-orange. The slightly lighter fleshed fruits can contain up to eight seeds and may have an astringent taste. With increasing maturity, the fruit softens, similar to a kiwifruit.

The high content of tannin in the still-immature kaki provides a bitter component reminiscent of a raw unpeeled chestnut, which weakens with progressive maturation. The furry taste, caused by the tannins, is reduced and finally completely disappears during the ripening process.

The astringent flavour can be removed by treatment with carbon dioxide.

Varieties

Kaki varieties are classified into four basic types, depending on the solubility of their tannin and the presence of seeds. Soluble tannin means that the fruit will have an acrid taste. Insoluble tannin means that there is no acrid taste. In some cases, the presence of seeds will turn the tannin insoluble in the whole of the fruit and in other cases only just around the seeds. this results in the following classification:
*PCA type: Pollination constant astringent. These kakis have a bitter taste until they become completely soft. The ripening process turns the tannin insoluble, after which all bitterness disappears and the sweet fruit can be enjoyed.
*PCNA type: Pollination constant non astringent, which is a relatively recent mutation in kaki fruit (a few centuries). In this type of kaki the tannin is always insoluble even when the fruit is still hard. This fruit will always taste sweet without any bitterness in the hard or soft stage.
*PVNA type: Pollination variant non astringent. This type of fruit has to become soft before it is edible except if it is seeded. A substance in the seed makes the tannin insoluble and thus the seeded fruit will be sweet even when it is still hard. Even one seed is usually sufficient to make the fruit edible. Fruit from the same tree that does not contain seed will taste bitter and needs to soften before it becomes edible.
*PVA type: Pollination variant astringent. This type of kaki is similar to the previous type but in this case only the flesh around the seeds will have no bitter taste. The rest of the fruit will taste bitter. This is due to a different process in tannin neutralization by the seeds. The result is that sometimes only half of the fruit (the part containing seeds) may be edible and the other half will be bitter if it contains no seeds.
Practically and commercially, only the first two kaki types are important. The other two types are considered astringent kakis for practical reasons and are handled just like the PCA type fruit.

Chemistry

Apart from tannins, triterpenoid compounds such as α- amyrin, uvaol, ursolic acid, 19α-hydroxy ursolic acid and 19 α,24-dihydroxy ursolic acid can be isolated from the leaves of ''D. kaki''.

The high content of the carotenoids beta-cryptoxanthin, beta-carotene, and zeaxanthin, along with some lutein