POSTHARVEST RESPIRATION IN GOLDEN DELICIOUS APPLES AS A FUNCTION OF ENVIRONMENTAL PO₂ AND PCO₂

The objective of this research was to determine simultaneously the amounts of O₂ consumed and of CO₂ produced by Golden Delicious apples at room temperature (21C) in a controlled atmosphere (P_tot=PO₂+PCO₂+PN₂; 0<PCO₂<75 kPa) [1,2]. The fruit were harvested 23 weeks after flowering and stored at 4C, 85% RH. To ensure a constant gas composition inside the storage cell, the quantity value of CO₂ produced by the fruits was continuously and automatically monitored by a gas-chromatograph (Fig. 1). Excess CO₂ was removed by an aqueous Ba(OH)₂ solution and replenished with pure oxygen.

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Fig. 1. A=Reactor containing the apples; B=Circulating pump; I=One way valve; L=Trap to collect C₂H₄ produced (aqueous KMnO₄); M=Graduated O₂ tank; N=Tank containing saturated aqueous soluton (NaCl).

The automatic monitoring of the experimental runs was carried out as follows: 1) every 45 minutes the gas-chromatograph (D), prompted by the computed (F) performed an analysis of the gas composition inside the storage cell; 2) the automatic sampler (C) collected the amount of gas necessary for the analyses; 3) the electrical signals from the detector of the gas-chromatograph (D) were sent to the interogrator/recorder (E); 4) the analytical reports produced by the integrator/ recorder (E) were collected, elaborated and then stored by the computer (F); 5) if the amount of CO₂ present inside the storage cell at a random time was greater than the sum of the initial value and the tolerance interval, the computer (F) inverts the electro-valve (G); 6) the gas was bubled through the CO₂ trap (H) for a period of time calculated by the computer (F) as a function of the amount of the gas to be absorbed and of the PCO₂ utilized; 7) when the amount of CO₂ produced by respiration was completely absorbed, the associated loss of pressure was automatically compensated for by the addition of a calculated volume

Physiological Basis of Postharvest Technologies

G. Andrich, A. Zinnai, S. Balzini, S. Silvestri, R. Fiorentini

https://doi.org/10.17660/ActaHortic.1993.343.35