Assessment of the mechanical properties of Tarocco orange fruit under parallel plate compression Original Research Article

In this work the mechanical compressive properties of orange fruits of the Tarocco variety were assessed using a Universal Testing Machine, equipped with upper and lower plates made of transparent graduated Plexiglas® and three cameras positioned along the axis lines x, y and z. By submitting each fruit to different engineering strains (εz) along the z-axis in the range of 3–21% of the initial fruit height, the momentary contact area of each fruit under testing was precisely determined by approximating its outline to a polygon and reconstructing it via the Elliptic Fourier Analysis, or an ellipse inscribed in a bounding box. Both estimates yielded no statistically significant difference and varied linearly with εz. Their prediction using the , or assuming no variation in the volume of the fruit undergoing compression, resulted be under- or over-estimated by 45% or 19%, respectively. Use of image analysis allowed the apparent Poisson’s ratio and modulus of deformability (EO) of the whole orange fruit to be estimated as equal to 0.16 ± 0.09 and 353 ± 3 kPa, respectively.