Delay of avocado (Persea americana) fruit ripening by 1-methylcyclopropene and wax treatments

Abstract

Abstract 1-Methylcyclopropene (1-MCP), an inhibitor of ethylene action, has been shown to extend the postharvest storage period of avocado fruit. Waxing is also known to extend the storage life of avocado by reducing water loss and modifying the fruit internal atmosphere. In this study, 1-MCP and waxing were used to investigate their combined effects on ripening characteristics of avocado fruit. Preclimacteric avocado ( Persea americana Mill. cv. ‘Tower II’) fruit were treated with 1-MCP (0.9 μl l −1 ) for 12 h at 20 °C. Half of the fruit were waxed (Sta-Fresh 819F ® , FMC FoodTech) after 1-MCP treatment and subsequently stored at 20 °C in ethylene-free air at 85% relative humidity. In a separate experiment, ‘Booth 7’ avocados were treated as above and stored at 13 °C. As evaluated by fruit firmness, ethylene evolution, and respiration rate, 1-MCP and wax significantly delayed the ripening of ‘Tower II’ avocado stored at 20 °C. Fruit treated with both 1-MCP and wax had better retention of green peel color and fruit firmness, and delayed climacteric ethylene evolution and respiration rates compared with other treatments. Waxing alone reduced weight loss and delayed softening, but did not delay climacteric ethylene evolution and respiration rates. Whereas firmness of control fruit decreased from >100 to 20 N over a 7-d period at 20 °C, fruit treated with both 1-MCP and wax required more than 11 d at 20 °C to soften to 20 N. The firmness of waxed ‘Booth 7’ avocados declined from >170 to 15 N during 19 d storage at 13 °C whereas fruit treated with both 1-MCP and wax required nearly 5 weeks to reach firmness values of 25 N. 1-MCP treatment, which completely suppressed polygalacturonase activity in ‘Tower II’ and ‘Booth 7’ fruit through 9 d at 20 °C and 36 d at 13 °C, respectively, significantly affected the rate but had little influence on the extent of fruit softening.