Abstract
The 'Saijo' persimmon fruit softens in a very short period of time after dry ice treatment for the removal of astringency. In order to lengthen the short shelf life, the effects of several kinds of deastringent and preservation methods were investigated : deastringent methods ; carbon dioxide (CO2), nitrogen (N2), continuous exposure and gradual reduction of CO2 (CO2 gradual reduction), dry ice and powder alcohol, preservation method ; sealed preservation in a plastic container after removal of astringency treatment by dry ice or powder alcohol. Ethylene production was inhibited by both 100% N2 and CO2 gradual reduction deastringency treatments compared to the CO2 treatment. But the degree of fruit softening was not affected by either treatment. This suggests that it is necessary to develop a new method for removing astringency that can decrease ethylene production below a certain threshold in order to delay fruit softening. Both unsealed and sealed fruit in a plastic container softened in 5 days after dry ice treatment. Unsealed fruit following powder alcohol treatment for removal of astringency softened in 7 days and sealed fruit softened in 40 days. Increased shelf life was observed in the sealed preservation after powder alcohol treatment compared with the dry ice treatment. The reason may be due to the preventing water deficit in the container maintaining low ethylene levels. These results indicate that sealed preservation in the plastic container after powder alcohol treatment for removal of astringency is useful for preventing fruit softening caused by the deastringency treatment.
