Textural Properties of Almonds

Textural properties of almonds were determined using standard penetration tests. Almond were placed on their longest side, and penetrated with a 2 mm diameter cylindrical probe mounted on a texture analyzer. The almonds were penetrated about 4 mm in depth with a test speed of 1.0 mm/s. The figure below shows the force-distance curve of a typical penetration test. Four mechanical properties were obtained. They are:

• Fracture force (N) — The force was recorded at the first peak and considered as an empirical measure of strength, corresponding to the force at the first major failure event;
• Stiffness (N/mm) — The relative stiffness was determined from the gradient of the force-deformation curve under the occurrence of first breaking event;
• Toughness (N⋅mm) — The area under the force-deformation curve up to 3 mm deformation was used as index of the toughness;
• Firmness (N) — The maximum force under the force-deformation within 4 mm deformation was considered as the firmness.