Effects of 1-methylcyclopropene and diphenylamine on changes in sensory properties of 'Granny Smith' apples during postharvest storage

Abstract

The objective of this study was to investigate and compare the effects of 1-methylcyclopropene (1-MCP) and diphenylamine (DPA) postharvest pre-storage treatments on changes in sensory properties of 'Granny Smith' apples during cold storage along with subsequent keeping of fruit at room temperature. Apples were stored in normal atmosphere (NA) at 0-1 degrees C/90-95 RH and evaluated after 3, 6 and 9 months (after removal from cold storage plus 1,.8 and 15 d at room temperature) by descriptive sensory analysis. Fourteen of the 17 evaluated attributes, in the form of an unfolded data matrix, were subjected to principal component analysis (Tucker-1). The combination of 11 sensory attributes, which loaded heavily on PC-1, was referred to as 'Freshness' axis. Three-way analysis of variance was applied on PC-1 scores for samples (PC-ANOVA). 1-MCP samples showed relatively low rates of juiciness, cohesiveness, hardness, crunchiness, greenness and sourness reduction during the observed period of storage as compared to Control and DPA samples. All of the evaluated 1-MCP samples practically appeared on the positive side of 'Freshness' axis in principal component space. The highest level of freshness loss during the storage period was observed in Control samples, which suffered changes in quality after the 9 months of storage at such a level that the fruit ware decayed and not suitable for consumption. The most resistant to scald forming were 1-MCP treated apples. No scald was found after 9 months of cold storage. The treatment of 'Granny Smith' apples with 1-MCP can extend the storage time in standard NA storage for at least 3 months without significantly losing freshness even two weeks after removal from cold storage, and is more effective in preserving sensory attributes related to apple freshness when compared with the DPA treatment.