Articles
PHYSIOLOGICAL AND BIOCHEMICAL CHARACTERISTICS AND KEEPING QUALITIES OF TEMPERATE FRUITS DURING CHILLED STORAGE
Information on keeping qualities, respiration, C2H4 and ACC production, chilling injury (CI) and resistance to fungus was obtained.
The kiwifruit fruits stored at -1.0°C were obviously sound for 40 days.
Thereafter the flesh color turned dark green, and the core became soft and wet due to low temperature effects.
The physiological changes of the fruits during chilled storage were as follows; firstly, the respiration increased, thereafter ion leakage occured. prior to the appearence of CI symptoms.
The plum fruits stored at 0°C and 7°C remained of marketable quality for 40 days and 20 days, respectively.
The optimum storage temperature of plum fruits would be 0–1°C, as the fruits stored at -1°C were obviously sound for the duration of 24 days, but thereafter CI developed gradually.
Fruits stored at below 0°C produced hardly any ethylene, due to a reduced ACC content, in spite of having as much ethylene forming enzyme (EFE) activity as fruits stored at 7°C. EFE activity declined with increasing duration of chilled storage.
A break point, in an Arrhenius plot of rate of potassium ion leakage from tissue discs of plum fruits, was found at -0.9°C. The break point corresponded closely with the critical temperature for CI of fruits.
On the flesh of chilled plum fruits white spots appeared after which the flesh became brown.
This browning occurred after a marked increase in the rate of ion leakage from the fruit tissues.
Satsuma mandarin fruits stored at 5°C had continuously little ion leakage from tissues and resistance to Botrytis cinera in storage.
The apple fruits stored under chilled temperatures of 0°C and -1°C – -2°C kept good appearence and quality.
Chilled storage is recognized to be an effective storage system, but low temperatures near freezing should be avoided.
Changes of ion leakage are probably a good indicator of the occurrence of CI during storage.
Positive control of ion leakage from tissues of fruits under long-term storage, must be taken.