Persimmon (Diospyros kaki Thunb.) is a good source of primary and secondary metabolites, which contents change during fruit ripening. It is necessary to specifically mention phenols among secondary metabolites, among which we also place tannins. At technological maturity, persimmon contains a lot of tannins, which can exist in soluble or insoluble form. Cultivars, which during technological maturity contain more soluble tannins, are astringent and inedible. For this reason it is necessary to remove astringency from the fruit. In a decade of finding optimal ways of removing astringency from the fruit there have been tested and used multiple techniques, among which we place: treating with high concentration of CO2, ethanol, high concentration of N2, treating with warm water, freezing the fruit, and treating with ethylene. These techniques count as the most useful for removing astringency. Treating with high concentration of CO2 has proven to be the most effective of all mentioned techniques. Effectiveness of the technique is guaranteed with activation of anaerobic respiration and consequent rises of acetaldehyde production, which reacts with soluble tannins. These polymerize into insoluble tannins during this process, which are no longer organoleptically active. In comparison with other mentioned techniques, treating with high concentration of CO2 in the shortest period of time, lessens the content of soluble tannins below lower limit of sensory perception (0.1 g/100 g of fresh weight) and at the same time preserves the highest quality of the fruit.
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