The physiological effect of fruit maturity and 1-methylcyclopropene on ‘Hass’ avocado fruit exocarp colour and chilling injury during ripening

Purpose: This study was undertaken to investigate the influence of harvest maturity and 1-methylcyclopropene (1-MCP) treatment on exocarp colour development and chilling injury of ‘Hass’ avocado fruit during ripening. Research method: ‘Hass’ avocado fruit harvested at three different maturity stages, early (21% DM), mid- (28% DM) and late (35% DM) were treated with 300 g mol-1 of 1- MCP for 16 hours and stored at 5.5 °C for 28 days, subsequently, ripened at 21 °C. The physico-chemicals quality parameters evaluated every 2 days includes exocarp subjective (visual colour), objective (lightness-L*, chroma-C* and hue angle-ho), chlorophyll-a and -b, total anthocyanin, cyanidin 3-O-glucoside and chilling injury. Findings: 1-MCP delayed ripening for early and mid-matured fruit and extended ripening by 2-4 days when compared with untreated fruit. In this study, exocarp colour development of ‘Hass’ avocado fruit was improved by 1-MCP treatment as measured visual and objectively. The accumulation of total anthocyanins and cyanidin 3- O-glucosides in 1-MCP-treated fruit was slower than that in untreated fruit, however, 1-MCP treatment was associated with higher concentrations after fruit had reached ‘eat-ripe’ firmness, irrespective of maturity. The study found that 1-MCP reduced the development of chilling injury symptoms for early harvested and mid-harvested ‘Hass’ avocado fruit. Research limitations: The main limitation of the present study is the lack of evaluation of ethylene production. Originality/Value: The study found that different maturity stages of ‘Hass’ avocado fruit responded differently to 1- MCP treatment. Thus, 1-MCP had a positive effect on early and midharvest fruit exocarp colour and CI development during ripening.