Vol. 87 No: 3

Title:
Response of kiwifruit (Actinidia deliciosa cv. Allison) to post-harvest treatment with 1-methylcyclopropene

Authors:
R.R. SHARMA, M.J. JHALEGAR and R.K. PAL

pp: 278-284

Abstract:
Experiments were conducted to observe the effect of different concentrations of 1-methylcyclopropene (1-MCP) on the post-harvest life and quality of ‘Allison’ kiwifruit (Actinidia deliciosa). Fruit were treated with 1-MCP at 0.5 μ l^-1, 1.0 μ l^-1, or 2.0 μ l^-1, un-treated fruit served as controls. Each 1-MCP treatment was applied for 24 h at 20°C. After treatment, fruit were transferred to ambient temperature storage (22º ± 4ºC; 65 – 70% relative humidity) for 18 d, during which time observations on various physical, physiological, and biochemical parameters were recorded at 3 d intervals. Our results indicated that 2.0 μ l^-1 1-MCP was the most effective treatment to delay softening and ripening in ‘Allison’ kiwifruit, as such fruit showed the lowest mean weight loss (9.8 ± 0.2%), the highest mean fruit firmness value (32.7 ± 0.2 N), and began to ripen only after 12 d in storage, whereas untreated fruit started ripening on day-6 of storage.The activities of fruit softening enzymes such as polygalacturonase (PG; 58.5 ± 0.3 μg galacturonic acid g^-1 FW h^-1), and lipoxygenase (LOX; 3.96 ± 1.3 μmoles linoleic acid oxidised min^-1 g^-1 FW h^-1) were lower, and total phenolics (TP) contents (24.3 ± 0.3 mg 100 g^-1) and anti-oxidant (AOX) activities (12.5 ± 0.03 μmol Trolox g^-1 FW h^-1) were higher in 1-MCP-treated fruit than in untreated fruit (PG, 98.3 ± 0.5 μg galacturonic acid g^-1 FW h^-1; LOX, 4.39 ± 1.0 μmoles min^-1 g^-1 FW h^-1; TP, 5.3 ± 0.6 mg 100 g^-1; AOX, 4.7 ± 0.02 μmol Trolox g^-1 FW h^-1, respectively). In addition, 1-MCP-treated fruit exhibited lower rates of respiration (48.3 ± 0.4 ml CO₂ kg^-1 h^-1) and ethylene production (30.2 ± 0.02 μl kg^-1 FW h^-1) than untreated fruit (58.9 ± 0.6 ml CO₂ kg^-1 h^-1; 38.7 ± 0.04 μl kg^-1 FW h^-1, respectively). Similarly, 1-MCP-treated fruit had higher titratable acidity (TA; 1.33 ± 0.3%) and ascorbic acid (AA) contents (115.9 ± 2.6 mg 100 g^-1 pulp) and lower soluble solids contents (SSC; 8.33º ± 0.2º Brix) than untreated kiwifruit (TA, 1.0 ± 0.2 %;AA, 105.3 ± 2.2 mg 100 g^-1 pulp; SSC, 13.7º ± 0.3º Brix, respectively). Thus, 2.0 μ l^-1 1-MCP can be used for the postharvest treatment of ‘Allison’ kiwifruit to enhance its shelf-life and marketability by approx. 6 d.

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