Selected primary and secondary metabolites in fresh persimmon (Diospyros kaki Thunb.): A review of analytical methods and current knowledge of fruit composition and health benefits

Diospyros kaki Thunb. (Ebenaceae) is a widely cultivated tree species in some countries of Asia, while in other continents persimmons are mostly considered “exotic” fruits. Peculiar characteristics of this species are a complex sex expression, parthenocarpy and fruit astringency at harvest time, associated with a different composition in polymerized flavan-3-ols. Analytical methods for determining sugars, vitamin C, carotenoids and polyphenols in persimmons were critically reviewed in order to evaluate the overall significance of literature results; the nutritional and nutraceutical properties, together with the health benefits of both astringent and non astringent cultivars, were also overviewed. To these aims, the available literature from the last twenty years and the most important formerly published papers were investigated using SciFinder®, Elsevier SciVerse, AGRIS, and PubMed search engines. Persimmons resulted rich in sugars (about 12.5 g/100 g FW), being fructose, glucose and sucrose the major components, and in total vitamin C, for which 100-150 g of fresh persimmon supplies the recommended daily amount. Astringent varieties supply higher amounts of sugars than nonastringent ones; conversely, higher concentrations of total vitamin C were found in nonastringent cultivars. The main carotenoid components are β-cryptoxantin (193 μg/100 g FW), β,β-carotene (113 μg/100 g FW) and β,ε-carotene (30 μg/100 g FW). Persimmons are also a good source of polyphenolic compounds such as p-coumaric acid, catechin, epicatechin, epigallo catechin, and condensed proanthocyanidins. This chemical composition, together with in vivo and in vitro studies, suggests a relevant role of persimmon in the protection against free radicals and in the prevention of some human diseases.