Evaluation Of Shelf Life And Ripening Of Imported Avocado 'Hass' Fruit Following Treatment With E+® Ethylene Remover Or 1-Methylcyclopropene (1-Mcp) During Medium-Term Cold Storage

Minimizing the effects of ethylene in storage facilities is fundamental to maintain postharvest quality of harvested crops. The ethylene action inhibitor 1-methylcyclopropene (1-MCP) has been used successfully on various climacteric commodities. On avocado (Persea americana Mill.) fruit, 1-MCP has been shown to delay the respiration climacteric, ethylene peak, softening and colour change. However, under certain conditions, 1-MCP-treated avocado fruit may ripen sub-optimally or unevenly. A recent study by Terry et al. (2007) demonstrated the ability of a newly developed palladium (Pd)-promoted material, now registered as e+ Ethylene Remover, to remove ethylene at cool temperatures to sub-physiologically active levels, hence to delay the ethylene-induced ripening of pre-climacteric avocado. Subsequent work showed that e+ Ethylene Remover effectively delayed late season avocado 'Hass' ripening during 26 days storage at 5°C and in conditions of high relative humidity. The present study compared the effects of e+ Ethylene Remover and 1-MCP on 1) manipulating ripening of early season avocado 'Hass' during 21 days storage at 5°C and 2) fruit capability to subsequently ripen when held 6 days under shelf life condition (20°C). Fruit firmness, colour, fatty acids and sugars content were assessed at defined intervals. e+ Ethylene Remover reduced ethylene levels to below 0.1 microliter L-1 within experimental boxes and maintained better firmness and greenness of fruit vs. controls. Likewise, 1-MCP strongly delayed fruit ripening during 21 days at 5°C. Upon transfer to shelf life conditions, fruit previously held with e+ Ethylene Remover ripened similarly to controls and were at eat-ripe stage (firmness <10 N) within 3 days at 20°C. However, fruit pre-treated with 1-MCP remained firm and green during 6 days shelf life and exhibited greater heterogeneity in ripening. Whilst delaying ripening of climacteric commodities is often desirable, it is equally important that the product ripen when required for consumption. In this context, e+ Ethylene Remover proved not only effective at delaying avocado 'Hass' fruit ripening during cold storage but also allowed normal ripening to resume when removed.