1-Methylcyclopropene application and modified atmosphere packaging affect ethylene biosynthesis, fruit softening, and quality of 'Tegan blue' Japanese plum during cold storage

This research was carried out to extend the postharvest storage of japanese plum (Prunus salicina Lindl. cv. Tegan Blue), which has a short shelf life limiting its export potential. The effects of 1.0 mu L center dot L-1 I-methylcyclopropene (1 -MCP) and modified atmosphere packaging (MAP), alone or in combination, on quality of mature japanese plum fruit during storage (0 +/- 1 degrees C and 90% +/- 5% relative humidity) were investigated. The activities of enzymes of ethylene biosynthesis [1-aminocyclopropane-1-carboxylic acid synthase (ACS), 1-aminocyclopropane-1-carboxylic acid oxidase (ACO), and 1-aminocy clopropane-1-carboxylic acid (ACC) content] and those of cell wall-associated enzymes [exo-polygalacturonase (exo-PG), endo-polygalacturonase (endo-PG), pectin esterase (PE), and endo-1,4-beta-D-glucanase (EGase)] were also measured. 1-MCP-treated fruit stored in normal atmosphere or in MAP had lower ACC content and inhibited ethylene production with reduced ACS and ACO activities compared with fruit stored in MAP and in normal atmosphere. Similarly, 1-MCP-treated fruit, stored either in normal atmosphere or in MAP, were firmer with reduced exo-PG, endo-PG, PE, and EGase activities compared with fruit stored in MAP and in normal atmosphere. During storage as well as during ripening, fruit stored in MAP exhibited a higher rate of respiration compared with other treatments. MAP exacerbated the effect of 1-MCP in reduction of ethylene production and fruit softening. 1-MCP application in combination with MAP after 5 and 7 weeks of storage delayed the fruit ripening by 10 and 8 days in contrast with control fruit, respectively. During storage, and as well as in ripe fruit, weight loss was reduced in fruit stored in MAP either with or without 1-MCP application. Control fruit and 1-MCP-treated fruit, stored in a normal atmosphere or in MAP, had the same values for the following parameters: chromaticity value L*, C*, and hue angle, titratable acidity, and concentrations of soluble solids, ascorbic acid, and total antioxidants. In conclusion, 1-MCP application in combination with MAP can be used effectively to reduce the ethylene biosynthesis and fruit softening during cold storage and to extend the storage life up to 7 weeks followed by 8 d of ripening without any adverse effects on the quality of ripe fruit.