Bruising appearance of apples:: involved parameters

After harvest, apples are submitted to various mechanical strains causing deformation and resulting in damage and quality loss. Bruise appearance and bruise volume are not only related to impact parameters (impact energy and absorbed energy), but also to the physiological status of the fruit. Bruising belongs to one of four typical appearances (A to D) according to the applied energy. Each appearance is related to one distinctive force-time and stress-strain impact curve. Percent of each bruising type changes with bruising extent (bruise volume/fruit volume), and with contribution of the flesh and of the skin to the overall physical properties (puncture firmness and toughness) of the fruit. For impact energies with the same magnitude, percent of type A appearance decreases during storage. Contrarily, percent of type B increases. Types C and D appear only for low impact energy and for overripe apple. Percent of type A is strongly correlated to mechanical properties of the flesh and that of type B depends on the skin properties.