The Study of Long-term Storage of Japanese Persimmon (Diospyros kaki Thunb.) 'Saijo'Fruits.

Abstract

The cause of rapid softening occurred in Japanese persimmon 'Saijo' fruits after removal of astringency by dryice (CO₂ gas from dryice) and also the possibility of long-term storage of the fruits by the combination of low temperature, polyethylene (PE) bag and ethylene absorbent were investigated.
The peak value of ethylene production which occurred after the dryice treatment was 2.2μl/kg· hr in 'Saijo', which was 10 times higher than that in 'Hiratanenashi'. These tests were conducted at 20°C.
The peak value of ethylene production in 'Saijo' fruits either treated with CO₂ gas or treated with dryice and packed with ethylene absorbent was about 1/10 of that in those treated with dryice and packed without ethylene absorbent. The fruits treated with CO₂ gas softened 2 days later and those treated with dryice and packed with ethylene absorbent did 10-15 days later than those treated with dryice and packed without ethylene absorbent. These tests were also conducted at 20°C.
The long-term storage tests were conducted in 2 years. In the first year, the fruits were harvested about 10 days later than a proper time and stored at lt in 0.05mm PE bag with ethylene absorbent after the treatment of dryice or CO₂ gas. The storage life with proper hardness of the fruits treated with dryice was 37 days, whereas that of those treated with CO₂ gas was 46 days. The apical parts of the fruits treated with dryice softened 10 days earlier than those treated with CO₂ gas. In the second year, the fruits were harvested at the proper time and stored at 2°C in 0.06 or 0.08mm PE bag with or without ethylene absorbent after the treatment of dryice or CO₂ gas. The storage life with proper hardness of the fruits packed with ethylene absorbent was 85 days, which was 13 days longer than that without ethylene absorbent. Ethanol contents in fruits increased linearly during the full period of storage, and acetaldehyde contents in fruits increased rapidly from 48 days after the start of storage. In both years, internal browning appeared in the flesh adjacent to calyx limitedly in the fruits treated with dryice.