Astringency of ‘Triumph’ persimmon fruits (Diospyros kaki L.) was removed before, during or after storage at −1°C, by treatment with 90% CO2 at 17°C. The duration of treatment required for total removal of astringency depended on the time of treatment, the tannin content at the time of its application, and the length of the storage period and subsequent shelf-life.
Pre-storage treatment of fruits for 24 hours induced an accelerated rate of softening during 2−4 months storage at − 1°C. When CO2 was applied under the same conditions, 2 weeks prior to termination of storage, the rate of softening was reduced, in comparison with pre-storage gassing, but was still greater than that of untreated fruit. Post-storage gassed fruit remained firmer during shelf-life than that gassed earlier. Treatments of shorter durations before, during or after storage, did not, however, reduce the rate of fruit softening but accelerated it. At all times of application, longer durations in CO2 atmosphere slowed down the rate of fruit softening, in spite of the accelerated softening of CO2-treated fruits vis-a-vis untreated fruit. These apparently contradictory effects indicate that CO2 treatment of persimmons affects two different systems involved in fruit softening.