Estimation of the Flesh Texture of Watermelon Fruits Using Elastic Surface Waves

We developed a technique for measuring the texture of watermelon (Citrullus lanatus) flesh using elastic surface waves.  The surface waves were created by the vibration of an oscillator attached to the fruit’s flesh, which transmitted the vibration along the surface of the flesh until it could be detected by an oscilloscope attached to a PZT bimorpfh actuator.  Wave velocity increases with increasingly crisp texture.  The velocity of the elastic surface waves along the flesh of the Japanese watermelon “Matsuribayashi 777” variety was faster than that of the Japanese “Wase-nissho” variety. In a sensory evaluation, panel members reported that “Matsuribayashi 777” had firmer texture than “Wase-nissho”, confirming the results obtained using elastic surface waves.  Our results suggest that it is possible to estimate the texture of watermelon flesh using elastic surface waves.