Crispness properties in apples rely on the sudden fracturing of the
intact flesh structure. The objective quantification of apples crispy feature
was difficult mainly due to the cellular tissue structure complexity.
When biting causes breaks, the released contents spread out rapidly and
a sound pressure wave is produced. The breaking of the flash structure
occurs during the first bite of the masticatory activities and tends to
decline with the mastication progress (Duizer, 2001). The structural
products properties with an auditory component are well described
for both dry crisp and wet crisp products, where cells contain air or
fluid, respectively.