Cracking characteristics and kernel extraction quality of hazelnuts: Effects of compression speed and positions

Figures & data

Figure 1. Representation of the three axial forces (F_x, F_y, and F_z) and three major perpendicular dimensions of hazelnut.

Figure 2. Typical compressive force deformation relationship of hazelnuts cv. Tombul.

Table 1. Evaluation of kernel extraction quality.

Classification	Definition	Grade
Very good	No damage	5
Good	Little damage	4
Mean	A small fracture occurred at the edge of the fruit	3
Bad	Divided into 2–3 parts	2
Very bad	Crushed	1

Table 2. Some physical properties of the Tombul hazelnut variety (at 11% w.b. moisture content of shell).

	1. Group				2. Group
	Mean	Minimum	Maximum	Standard deviation	Mean	Minimum	Maximum	Standard deviation
Length (mm)	17.77	14.98	20.20	0.98	16.63	14.00	18.89	0.93
Width (mm)	16.49	14.87	18.47	0.72	15.30	12.75	17.51	0.94
Thickness (mm)	15.87	13.97	18.41	0.68	14.66	11.91	15.96	0.75
Weight (g)	1.76	0.92	2.44	0.24	1.44	0.66	1.80	0.22
Geometric mean diameter (mm)	16.68	16.08	17.69	0.41	15.49	13.55	16.08	0.51
Volume (cm^3)	2.03	1.60	2.70	0.20	1.63	1.10	2.10	0.21
Shell thickness (mm)	0.89	0.66	1.21	0.12	0.84	0.59	1.11	0.10

Table 3. Effects of compression positions on force, energy, specific deformation, and kernel extraction quality of hazelnuts.

	Force (N)		Energy (J)		Deformation (%)		Kernel extraction quality (grade)
Direction	FG	SG	FG	SG	FG	SG	FG	SG
Fx (length)	211	179	0.100	0.082	6.26	6.79	5.00	4.89
Fy (width)	178	145	0.103	0.084	6.60	6.67	5.00	4.78
Fz (thickness)	189^ns	180^ns	0.087^ns	0.086^ns	5.70^ns	7.34^ns	4.61^ns	4.83^ns

ns: Not significant.

FG: first group; SG: second group.

Table 4. Effects of compression speed on force, energy, specific deformation, and kernel extraction quality of hazelnuts.

	Force (N)		Energy (J)		Deformation (%)		Kernel extraction quality (grade)
Velocity (mm/s)	FG	SG	FG	SG	FG	SG	FG	SG
0.5	177b*	145b	0.103^ns	0.084^ns	6.60^ns	6.67b	5.00a	4.78ab
1.0	165b	162ab	0.102	0.095	7.20	7.51b	4.83a	5.00a
1.5	189ab	187a	0.137	0.132	9.43	9.23ab	4.21b	4.14b
2.0	214a	160ab	0.126	0.125	7.85	11.5a	3.96b	3.13c

*Means in columns followed by the same letters are not significantly different.

ns: Not significant.

FG: first group; SG: second group.

Figure 3. Mean values of force, compressed at three positions (length, width, and thickness), as a function of shell thickness.

Figure 4. Mean values of energy, compressed at three positions (length, width, and thickness), as a function of shell thickness.

Figure 5. Mean values of specific deformation, compressed at three positions (length, width, and thickness) as a function of shell thickness.

Figure 6. Mean values of rupture force, compressed at three positions (length, width, and thickness) as a function of geometric mean diameter.

Figure 7. Mean values of energy, compressed at three positions (length, width, and thickness) as a function of geometric mean diameter.

Figure 8. Mean values of specific deformation, compressed at three positions (length, width, and thickness) as a function of geometric mean diameter.