The effect of relative humidity and ethylene scrubbing on 'Fuerte' and 'Hass' avocado fruit quality

Throughout the industry the handling technologies for avocados are constantly being evaluated and adapted so as to meet the changing demands of the export market for high quality fruit. In laboratory-scale trials, ‘Fuerte’ and ‘Hass’ avocados were stored at non-chilling temperatures (5.5°C and 7°C, respectively) and chilling temperatures (3°C and 5°C, respectively), both in combination with a high (100%) and a low (75%) relative humidity for 28 days. Thereafter, the fruit were ripened in air at 20°C before evaluation. Once eating ripe no more than 44% of the fruit within a treatment for either of the cultivars was sound. The fruit were mostly affected by the internal disorders, grey pulp and vascular browning, while the ‘Hass’ avocados also had prominent levels of decay. Although previous research has shown that high RH can restrict chilling injury and extend shelf life of avocados, this was not apparent in our work. In a second, semi-commercial trial, ‘Fuerte’ and ‘Hass’ avocados were exported from South Africa to France in 20 m controlled atmosphere (CA) integral reefer containers. Potassium permanganate scrubbers used commercially by the industry, were removed from one container to test the effect of ethylene scrubbing on fruit ripening and quality. During the voyage, ethylene levels in both control and scrubberless containers remained very low. Fruit quality on arrival and after ripening showed no differences between the scrubbed and non-scrubbed containers. It was concluded that scrubbers may be unnecessary when shipping fruit under the CA conditions used in this trial. tive humidity (RH) levels (95%+) during storage have been proven to restrict chilling injury (Chien et al., 1998) and ripening of different fruit (Adato and Gazit, 1974; Pesis et