Dehydration and Astringency Removal from Persimmon Flesh by Osmotic Pressure, and Study of Fruit Quality

Abstract

　The astringency of peeled persimmon fruit (Diospyros kaki Thunb.) after harvest can be removed during drying. Dehydration and astringency removal may also be induced via osmotic pressure by dipping the flesh in a concentrated sucrose solution. We examined the influence of dipping conditions and fruit maturity on the degree of dehydration and loss of astringency in persimmon flesh. Peeled fruits were individually dipped in a sucrose solution in a small plastic container that was sealed with a lid and kept under a constant temperature for several days. Dehydration of the flesh in 50°Brix sucrose solution progressed faster as the temperature increased from 35℃ to 50℃. However, the degree of dehydration was similar for all conditions after 7days of dipping. Dehydration progressed faster and the magnitude was greater as fruit maturity advanced. Although a loss of astringency did not occur in flesh dipped at 5℃, astringency disappeared rapidly in the flesh as the dipping temperature increased to between 20℃ to 50℃. The loss of astringency occurred more easily in mature than immature flesh. The ease of astringency loss varied among years. The total scores for product quality with respect to taste were higher for more mature fruits, except when they were overripe. These results suggest that the flesh from fruit at 80—100% maturity was suitable for processing. The fruit quality was different from traditional dry or semi-dry persimmon in the texture and was influenced by cutting and by the cultivar used.