Postharvest Ripening and Quality of Guatemalan-West Indian Avocado Hybrids under Simulated Commercial Shipping Temperatures Following Treatment with Aqueous 1-Methylcyclopropene.

TWO Guatemalan-West Indian avocado (Persea americana) hybrids ('Monroe' and 'Booth 8') were treated with an aqueous formulation of 1-methylcyclopropene (1-MCP) to determine effects on ripening and quality during storage simulating commercial shipping temperatures. Fruit harvested at preclimacteric stage were immersed in aqueous 1-MCP at 75 µ g⋅L^-1 (1.39mmol ⋅ m^-3) or in deionized water for 1 minute, stored at 10 °C for 14 days, and then transferred to 20 °C until ripe. Respiration rate, ethylene production, softening, and change in epidermal hue* angle were delayed and/or suppressed in both cultivars exposed to 1-MCP, although effects were less pronounced with Booth 8. Hue* angles for 1-MCP-treated 'Monroe' fruit had the highest values (darkest green peel color) of all treatments at full-ripe stage (hue* angle = 117). For control and treated 'Monroe' fruit respiration peaked on days 15 and 21, while ethylene production from both treatments peaked on day 16. Respiration and ethylene production peaked on day 16 for both control and 1-MCP-treated 'Booth 8' fruit. Fruit treated with 1-MCP consistently showed diminished respiration and ethylene peaks. Days to full-ripe stage were unaffected by treatment. 'Booth 8' fruit from both treatments were considered ripe (15 N whole fruit firmness) after 17 days; however, only 8% of control fruit were marketable, whereas 58% of 1-MCP-treated fruit were marketable, based on subjective appearance ratings using the Jenkins-Wehner score. The development of peel blemishes during storage was the primary cause of unmarketable fruit. 'Monroe' control and 1 -MCP-treated fruit were soft after about 22 days and were significantly more marketable (control 70% and 1-MCP 85%). Avocados treated with 1-MCP ripened over a longer period than control fruit but maintained a higher percentage of marketable fruit. [ABSTRACT FROM AUTHOR]