Effect of ripening on the mechanical properties of Portuguese and Spanish varieties of olive (Olea europaea L)

The mechanical properties of the table olive, Hojiblanca and Douro varieties from Spain and Portugal respectively, were determined. The results showed that in a tensile test the skin was stronger and stiffer than the flesh. This was also reflected by the strain at failure of the two tissues, the skin being less deformable than the flesh. During ripening, the strength of both skin and flesh of Hojiblanca decreased, whereas the skin and flesh of Douro increased and decreased in strength respectively. In general, Hojiblanca tissues were stronger than Douro tissues. A softening phenomenon was detected during ripening in the flesh of both varieties. The stiffness of the skin of Hojiblanca decreased significantly during ripening, whereas that of the skin of Douro increased but to a lesser extent. However, in general, the skin and flesh of Hojiblanca were stiffer than those of Douro. A cutting test enabled the determination of skin and flesh toughness. However, it is suggested that the flesh contributed to the measurement of skin toughness in the early stages of ripening, as reported for other commodities. The flesh of Hojiblanca was tougher than that of Douro, with both decreasing in toughness during ripening.