Abstract
Mature Satsuma oranges (Citrus unshiu Marc.) were harvested on November 27, 1968 and were stored at various temperatures and 80-90% R. H. Decaying condition and respiration of fruits, changes in sugar, acid and ascorbic acid concent of juices, were studied during and after storage.
1. At 20°C, the decay by stem-end rot increased rapidly after 60 days of storage, and marked shriveling appeared on the peels of fruits. Although the fruits stored at 10°C maintained its keeping qualities for a longer period (120 days), eventually the shriveling and stem-end rot occurred. At lower temperatures, 2°C and 5°C, the decay by penicillum mold increased rapidly after 120 and 160 days of storage, respectively. The shriveling of peel could not observed in the fruits at the both temperatures. The fruit at 2°C, however, showed symptom of chilling injury from the middle of April, and objectionable graying developed on the peel.
At 2°C, a pronounced decrease in respiration occurred soon after the beginning of storage, and the low respiration level remained constant until the increasing time of decay, when a slight increase in respiration took place. The same pattern of respiration was observed in the other cases.
In below 6°C, ascorbic acid and sugar concentration of juice, which extracted from fruit, remained approximately the same as in the fruit before storage, but total acids concentration and sugar concentration decreased remarkably even in undecayed fruit at the end of storage period as compared with those of fruit stored low temperature.
At 2°C, evolution of volatile substances from the fruits increased pronouncedly with the development of chilling injury, and those fruits were always accompanied with the rise of respiration.
2. CO2 production of fruits transferred from 2°, 6° and 10°C increased for the first 8-12 hours after transfer to 20°C and then decreased, and it was evident that there was a cumulative time-temperature influence of chilling exposure upon the degree of stimulation in CO2 evolution.
The low temperature during storage resulted in the notable decrease of chemical compositions in fruit juices after transfer to 20°C.
Naturalization, in which the temperature of fruits rised gradually, prevented the rapid rise of respiration. And also, number of decayed fruits and decrease of chemical compositions of fruits in this treatment were more less than those of fruits transferred directly to 20°C.
