Sensory and Objective Evaluation of Postharvest Fruit Softening and Its Relationship with Pectin Solubility in Eight Commercial Cultivars of Muskmelon (Cucumis melo L. var. reticulatus Naud.)

Abstract

Postharvest modification of flesh firmness and its relationship to pectin solubility were investigated in eight commercial cultivars of muskmelon (Cucumis melo L. var. reticulatus Naud.). A considerable difference in the softening rate was found between cultivars. Relatively rapid softening to desirable texture was found in the flesh of 'Sapporo King ER', 'Melorin', and 'King Melty' within three or four days after harvest. The flesh of 'Ichihime', 'Red 113', and 'G 08' showed slower softening, taking approximately a week to obtain acceptable texture. Especially in 'Ichihime' and 'Red 113', the flesh remained relatively firm even after 14 days. 'Rupia Red' and 'Earl's Knight Shunjukei' showed an intermediate softening rate. These characteristics corresponded to the objective measurement, and a logarithmic relationship was found between sensory scores of flesh firmness and hardness measured by texture analyzer. Furthermore, significant differences between cultivars in the rate of pectin solubilization were observed, which corresponded to the rates of flesh softening. A significant negative correlation was observed between texture analyzer-measured hardness and water-soluble pectin content, which seemed to fit an exponential curve. The hardness for acceptable eating quality varied from cultivar to cultivar. The contribution of this objective method of measuring flesh firmness to the evaluation of eating quality, and its difficulty due to differences in postharvest behavior of cultivars, are discussed.