Relationship of IAD index to internal quality attributes of apples treated with 1-methylcyclopropene and stored in air or controlled atmospheres.

Toivonen, P.M.A. and Hampson, C.R. (2014). "Relationship of IAD index to internal quality attributes of apples treated with 1-methylcyclopropene and stored in air or controlled atmospheres.", Postharvest Biology and Technology, 91, pp. 90-95. doi : 10.1016/j.postharvbio.2013.12.024  Access to full text

Abstract

The research was conducted to evaluate the relationship between I{SUB}A{/SUB}{SUB}D{/SUB} index (index of absorption difference between 670 and 720 nm) values and internal quality attributes of apples treated with 1-methylcyclopropene (1-MCP) and stored in air and controlled atmospheres (CA). Apples of ‘8S6923’ (Aurora Golden Gala™), ‘Fuji’ and ‘Royal Gala’ were tested. The results with Aurora Golden Gala™ show that I{SUB}A{/SUB}{SUB}D{/SUB} index values were maintained at higher levels if the fruit were stored in CA and that 1-MCP had no significant effect on retaining at-harvest values. The I{SUB}A{/SUB}{SUB}D{/SUB} values correlated with chlorophyll a content in the peel (R2 = 0.95, P < 0.0001), but not with chlorophyll b content, internal ethylene levels, firmness or titratable acidity. ‘Royal Gala’ apples showed a similar response to Aurora Golden Gala™ apples, showing no correlation between I{SUB}A{/SUB}{SUB}D{/SUB} index values and internal quality attributes of those apples when treated with 1-MCP and/or CA. In contrast, ‘Fuji’ apples showed a relationship between I{SUB}A{/SUB}{SUB}D{/SUB} index value changes and internal ethylene concentrations (R2 = 0.67, P < 0.05) and titratable acidity changes (R2 = 0.89, P < 0.01), but not firmness. These results suggest that when 1-MCP and/or CA are applied to apples after harvest, that I{SUB}A{/SUB}{SUB}D{/SUB} index values do not consistently correlate to any internal quality attributes other than peel chlorophyll a content.

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