Mechanical behaviour of hazelnuts used for table consumption under compression loading

Nuts of four hazelnut varieties and five new selections used for table consumption were compressed at the moisture content of 6% w.b. to measure shell resistance to breakage. Rupture force, rupture energy and nut specific deformation were measured under three compression loading positions. Physical parameters of nuts were also evaluated to relate them the data obtained by compression test measurements. Rupture force and nut specific deformation are the most discriminant parameters that can be used to describe the behaviour under compression while rupture energy values show fewer differences among the considered varieties. The values of force required to break nut shell ranged from 322 to 769 N. The lowest values of force were generally obtained along Y-axis. Nut specific deformation ranged from 3.35% and 11.76%. Correlation among physical and texture parameters showed that values of force, energy and deformation are dependent on different parameters that varies in the three considered axis. The nuts of Ennis and Barcelona varieties show high mean values of force rupture to break shell and low deformability. Among the new selections, L35 and B6 are easy-to-break nut, with 428 N of mean value of force rupture and 8% of nut specific deformation, are desirable for table consumption.