Determination of optimum ripeness for edibility of postharvest melons using nondestructive vibration

We investigated time-course changes in the elasticity index (EI) of two melon (Cucumis melo   L.) cultivars (“Andes” and “Quincy”) during their postharvest period. The EI was determined using the formula EI=f22·m2/3, where f2 and m were the second resonance frequency and the mass of the sample, respectively. A nondestructive vibrational method with laser Doppler vibrometer (LDV) was used for measuring the second resonance frequency (f2) of the melon samples. The changes in the EI of both cultivars showed quasi-exponential and biphasic decays. Along with sensory tests, we determined the optimum ripeness for edibility of the melons in terms of their EI to be 4.2–6.3 × 104 kg2/3 Hz2 (“Andes”) and 4.5–5.6 × 104 kg2/3 Hz2 (“Quincy”). Therefore, predetermined EI of two melon cultivars enables consumers to predict the time range of optimum ripeness.