TOTAL POLYPHENOL, PROANTHOCYANIDIN AND FLAVONOID CONTENT, CARBOHYDRATE COMPOSITION AND ANTIOXIDANT ACTIVITY OF PERSIMMON (DIOSPYROS KAKI L.) FRUIT IN RELATION TO CULTIVAR AND MATURITY STAGE

P. Denev, A. Yordanov

Abstract: The current study investigates the total polyphenol, proanthocyanidin and flavonoid content, the carbohydrate composition, and antioxidant activity of persimmon fruit (Diospyros kaki L) from five cultivars (Hyakume, Moro, Hiratanenashi, Jiro C 24276 and Mandarino). Fruits were analyzed at two maturity stages - commercial harvest stage and physiological ripening stage. The HPLC analysis showed that glucose and fructose were the predominant sugars in the fruit. At commercial harvest stage total sugar content varied in the range 9.6 – 14.4 g/100g FW and increased slightly to 11.5-16.5 g/100g FW after maturation, being the highest in Hiratanenashi cultivar. Generally, the polyphenol content and particularly the proanthocyanidin content were strongly affected by the cultivar and maturity stage. The highest polyphenol and proanthocyanidin content at commercial harvest stage showed Hiratanenashi persimmon (916.8 mg GAE/100g FW and 540.2 CE/100g FW, respectively. The content of both polyphenols and proanthocyanins decreased proportionally during the maturation. At physiological ripening stage, again Hiratanenashi was the richest source of polyphenols and proanthocyanidins - 400.2 mg GAE/100g FW and 90.2 CE/100g FW, respectively. Persimmons showed different antioxidant activity depending on cultivars measured by Oxygen Radical Absorbance Capacity (ORAC) and Hydroxyl Radical Averting Capacity (HORAC) methods. At commercial harvest stage the pollination variant astringent cultivar Hiratanenashi has the highest ORAC and HORAC values - 49.2 μmolTE/g FW and 30.2 μmolGAE/g FW, respectively. After the maturation of the fruit of all cultivars, a more or less decrease in both ORAC and HORAC values was observed, proportionally to the decrease of the total polyphenol content.

Keywords: antioxidant activity; HORAC; ORAC; Persimmon (Diospyros kaki L.); polyphenols; proanthocyanidins

Date published: 2019-01-28