Relationship Between Changes in Electrical Conductivity and Ethylene Production in Avocado Fruits

Abstract

Electrical conductivity measurements were carried out in 'Hass' avocado fruit during storage under various conditions and during ripening when the fruit were transferred to 20°C. Refrigerated storage trials were carried out under normal atmosphere and modified atmosphere at 4°C, just below the critical temperature of 5°C for this cultivar. In parallel with the electrical parameter, pulp firmness, respiration rate and ethylene production were obtained to estimate the time course of ripening in avocado. Electrical conductivity of non-refrigerated fruits increased slightly during the first 5 d after harvest. Afterwards, it grew rapidly and reached a maximum on the 7th day. A drop in electrical conductivity was observed when the fruits became overripe by about Day 10. The onset of a steep rise in conductivity was followed by softening and reflected the beginning of the ripening process. Moreover the electrical conductivity peak rose at the same time as the ethylene peak. These results have allowed us to set the electrical conductivity as a maturity index that is simple and rapid to measure. In refrigerated fruits transferred to 20°C, the same electrical conductivity pattern was also found. This curve together with the ethylene and respiratory curves were slightly modified by both storage conditions and storage period. These alterations were strong when chilling injury occurred.