Optimization of the extraction of polyphenols from astringent and non-astringent persimmon fruit by aqueous ethanol solution
The high antioxidant activity of persimmon fruit is related to its large content of polyphenols. In order to optimize the polyphenols extraction by aqueous ethanol solution from astringent- and non-astringent persimmon fruit (Diospyros kaki 'Mopan' and 'Youhou', respectively), the orthogonal experiment design was used to evaluate the effect of single factors such as temperature, ethanol concentration, and time. The content of polyphenols was determined by Folin-Ciocalteu's method. The extraction temperature (20, 60 and 100°C) had a great effect on the extraction of polyphenols. The amount of polyphenols extracted from astringent persimmon fruit increased gradually as the temperature increased; however, the amount of polyphenols extracted from non-astringent fruit was slightly higher at 20°C than at 60°C or 100°C. Ethanol concentration (50, 75, 100%) affected slightly the extraction of polyphenols from astringent persimmon fruit, while the amount of polyphenols extracted from non-astringent fruit decreased significantly as the ethanol concentration increased. Among the extraction times that were studied (0.5, 1, and 2 h) the higher yield from astringent fruit was obtained at 1 h, however, from non-astringent type the yield decreased gradually with the increase of extraction time. In a verification experiment using the optimal ethanol solution and extraction duration, the efficiency of the extraction depended on the temperature. The extract from non-astringent fruit with the highest concentration of polyphenols was obtained at 20°C, and the efficiency decreased as the temperature increased. The polyphenols extraction yield from astringent fruit increased when the temperature was raised. In conclusion, when ethanol solution is used to extract persimmon fruit polyphenols, the efficiency of the extraction depends on the temperature and type of persimmon (astringent and non-astringent).
He, Shuixian, Li, Ran and Li, Bao (2018). Optimization of the extraction of polyphenols from astringent and non-astringent persimmon fruit by aqueous ethanol solution. Acta Hortic. 1195, 183-188
Diospyros kaki, polyphenols, ethanol, temperature