In this experiment American Summer Pairman apple was selected as test fruit in order to study the effect of sub-atmospheric pressure storage in the apple.
Keeping a certain pressure condition, a new sub-atmospheric pressure system was designed and constructed in which fruits were stored at 25℃ under two different atmospheric pressure conditions such as Normal Atmospheric Pressure (NAP) and Sub-Atmospheric Pressure (SAP). Moreover, they were divided into plots of 5% and 0% of CO₂, on the basis of gas composition. Under these conditions, the amount of respiration and ethylene evolution, and the changes of intercellular gas composition and organic components were investigated throughout the storage.
The results obtained are as follows:
(1) The intercellular gas was exhausted so rapidly by the SAP treatment that the gas equilibrium in the tissues reached within 5 minutes.
(2) The amount of respiration was found to be higher in plots of NAP than SAP, and under the conditions, controlling CO₂ content, plots of CO₂ 5% were lower in the amount of respiration than CO₂ 0%.
The climacteric rise was revealed more slowly in plots of the SAP than NAP. These results indicate that the SAP treatment was an efficient method for controlling the respiration of fruits. Furthermore, these results were also realized with the results of the respiratory quotient (R. Q) and intercellular gas composition.
(3) Evolution of ethylene, the ripening hormone in plant, was shown the similar tendency to the climacteric pattern of respiration; at the stage of climacteric maximum, the maximun amount of ethylene was found earlier in plots of NAP than SAP, and post climacteric stage was prolonged in the plots of the SAP compared to those of the NAP.
The ethylene concentraion in tissue appeared lower in plots of the SAP than NAP, which might suggest that the SAP treatment was caused to restriction of ethylene evolution.
(4) Effects of the SAP treatment mentioned hitherto were proved also with the test of the external appearance such as changes of color and freshness, firmness, rotting and weight loss.
(5) In the investigation of organic components, vitamin C and organic acids varied less in plots of SAP than NAP. Specially, it was remarkable that the loss of malic acid was least decreased by the SAP treatment. These effects of the SAP treatment were distinctive in the changes of the ratios of malic and citric acid to total acid, and the ratios of free sugar to free acid.
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