2014 ASHS Annual Conference

Our research with ‘Kent’ and ‘Keitt’ mango has shown that aqueous 1-MCP provides a moderate delay of ripening but had a negative interaction with quarantine hot water treatment (46.1 °C, 90 min). Fruit treated with aqueous 1-MCP before or after heating developed fair to poor external appearance. By contrast, fruit treated with aqueous 1-MCP without heating showed delayed ripening without adverse effect. The objective of this study was to determine the physiological processes involved in the response of unheated and heated mango and papaya fruit to 1-MCP. 1-MCP sorption in whole or fresh-cut fruit was determined by enclosing mango or papaya fruit or tissue in plastic containers of 6.7 L that were sealed and injected with 20 µL L^-1 gaseous 1-MCP. 1-MCP depletion was monitored over 6 h using gas chromatography. For 1-MCP ingress in intact papaya, single fruit were placed in similar containers and gaseous 1-MCP injected at 20 µL L^-1. At selected intervals jars were opened and fruit immediately immersed in plastic bins containing 10 L diH₂O. Samples of internal atmosphere were taken by syringe from the apical, middle and basal tissues, and from the cavity of the immersed fruit. 1-MCP concentration was measured using gas chromatography. Internal gaseous 1-MCP in quarantine hot water treated (48.0 °C for 75 min) or untreated intact papaya fruit treated with aqueous 1-MCP was monitored in a similar manner. ‘Kent’ and ‘Keitt’ mangos showed different patterns of 1-MCP sorption, but 1-MCP sorption trends were similar for heated and unheated mangos. Moreover, the 1-MCP sorption rate of fresh-cut ‘Keitt’ fruit was 2-fold higher than that of whole fruit. With respect to papaya, no significant differences in gaseous 1-MCP sorption were noted between heated and unheated whole fruit, but significant differences were found for fresh-cut tissue from heated and unheated fruit. Heated fresh-cut tissue adsorbed more 1-MCP than unheated fresh cut tissue. Significant differences were also found in papaya for gaseous 1-MCP exposure time: the longer the exposure time, the higher the ingress of gaseous 1-MCP. Finally, with relation to experiments measuring the ingress of aqueous 1-MCP in papaya fruit, no significant differences were found between heated and unheated fruit, 1 or 5 min dipping time, or sampling regions (apical, middle, basal, or cavity). However, significant differences were detected between 1 mg L^-1 and 3 mg L^-1 1-MCP in the experiment conducted in January, but not in the experiment conducted in December.