Effect of Prestorage High Temperature Conditioning on Fruit Quality, respiration and Ethylene Production of 'Hass' Avocado Fruit

Abstract

Late-harvested ‘Hass’ avocado ( Persea americana Mill.) fruits were stored at 5°C for 0, 2, 4 or 6 weeks after being conditioned at 38°C for 0, 12, 24 or 36 hr. High temperature conditioning advanced the carbon dioxide peak in fruit exposed for 12 hr to high temperature and slightly lowered the magnitude of the climacteric in fruit heated for 36 hr. Ethylene evolution rate decreased as the time in storage and the exposure to high temperature increased. Heat treatment was detrimental in fruits exposed for 36 hr. These failed to ripen and showed severe heat injury, decay incidence and internal browning. In 24-hour heat-treated fruit, a significant delay in reaching the soft-ripe stage was obtained following removal to shelf-life ‘exposure’. Results of this study indicate that ‘Hass’ avocado fruit do not tolerate exposure at 38°C for longer than 24 hr, and that even shorter times of exposure may cause heat injury.