Simultaneous measurement of apple flesh and apple skin firmness by puncture testing

Simultaneous assessment of apple flesh and apple skin firmness was studied by comparison of force-deformation curves from puncture tests at constant velocity (20 cm.min(-1)) with a 4 mm punch on intact and peeled fruit. Results from tests with and without skin may be compared together and allow "EFFEGI" firmness values to be inferred, although they are underestimated by 1.5%. Puncture tests through the skin enable simultaneous measurements of fruit flesh and skin. One single measurement of the force-displacement curve obtained with the skin present gives the flesh breaking-down point through extrapolation and yields the elasticity coefficient. The difference between total puncture force and the flesh rupture breakdown force yields data related to the physical status (turgidity or drying) of the skin and the underlying cells.