Our first development was a destructive method based on acoustic emission to evaluate tissue cracking and the prediction of sound-related sensory texture. Typical macroscopic measurements of mechanical properties to test puncture, compression, tension or three-point bending have been completed while monitoring the acoustic emission signal. The acoustic emission signal is recorded by a contact sensor (no air-conducted sound) which substantially improves the signal-to-noise ratio. Moreover, from the perspective of a consumer, an acoustic signal transferred through the bones is the primary source of crispness evaluation. We have used these results to develop a stand-alone device for the instrumental evaluation of apple texture called a CAED (contact acoustic emission detector. In general, we use acoustic emission for the detection of the onset of cracking and to follow the destruction process of fruit. With this method we could successfully predict the sensory crispness, juiciness and hardness of apples.
