Firmness evaluation of watermelon and melon using velocity dispersion of surface-acoustic-wave

Abstract The surface-acoustic-wave (SAW) velocity was measured in the frequency range of 400–7000 Hz watermelon and melon to evaluate firmness nondestructively. We showed that positive dispersion (velocity increases with increasing frequency) observed caused by fruit structure, which consists a hard pericarp underlying soft flesh. In watermelon, low-frequency limit curve for predicted SAW flesh, be independent frequency. melon, dispersions as well flesh suggested distribution elasticity depth direction. Ripening fourteen days decrease 34%–57% depending on present results demonstrate is good measure ripening fruits.