2.3. Determination of mechanical properties
Each sample was put in a moist sand container under the 4 mm diameter spherical plunger of the Universal Testing Machine (UTM) Instron 5569 in such a way that its stem axis was parallel to the horizontal plane. The UTM slowly pressed the plunger into the young coconut surface at its equator at a loading rate of 25 mm min−1 (ASAE Standard, 1994) until rupture of the husk. The point of application of the slow compression was at the middle of the ridge and face of the fruit. Six application points were used for each sample. Husk rupture force, deformation at rupture and the slope of the force-deformation curve were analyzed. The same process was repeated with 20 samples every four days until the 206th day afte