Moisture-dependent physical properties of melon (Citrullus colocynthis lanatus) seed and kernel relevant in bulk handling

Figures & data

Figure 1. Melon dimensions

Table 1a. Mean value and standard deviation of some geometric properties of melon seed at different moisture content levels

MC (%, d.b.)	L (mm)	W (mm)	T (mm)	D g (mm)	D a (mm)	S a (mm^2)	S p	R a (%)	V (mm^3)
2.8	13.91 (0.70)	8.49 (0.50)	1.71 (0.71)	5.81 (0.50)	8.04 (0.40)	106.87 (23.21)	0.42 (0.04)	61.15 (3.62)	42.40 (3.94)
7	14.27 (0.81)	8.79 (0.56)	1.96 (0.73)	6.21 (0.52)	8.34 (0.42)	121.98 (23.72)	0.43 (0.04)	61.72 (4.34)	44.82 (4.44)
12	14.32 (0.82)	8.82 (0.60)	2.08 (0.42)	6.37 (0.47)	8.41 (0.41)	128.38 (19.66)	0.45 (0.03)	61.70 (4.64)	45.20 (4.61)
17	14.35 (0.85)	8.85 (0.55)	2.13 (0.46)	6.43 (0.49)	8.44 (0.39)	130.74 (19.99)	0.425 (0.03)	61.84 (4.78)	45.38 (4.49)
25	14.37 (0.85)	8.88 (0.56)	2.16 (0.25)	6.44 (0.34)	8.41 (0.72)	132.09 (19.63)	0.45 (2.68)	61.94 (4.68)	45.57 (4.56)

Notes: MC is the moisture content (%, d.b.); L is the length (mm); W is the width (mm); T is the thickness (mm); D _g is the geometric mean diameter (mm); D _a is the arithmetic mean diameter (mm); S _p is the sphericity (%); S _a is the surface area (mm²); R _a is the aspect ratio; and V is the volume (mm³). Standard deviations are in parentheses.

Table 1b. Mean value and standard deviation of some geometric properties of melon kernel at different moisture content levels

MC (%, d.b.)	L (mm)	W (mm)	T (mm)	D g (mm)	D a (mm)	S a (mm^2)	S p	R a (%)	V (mm^3)
1.1	13.24 (0.82)	7.71 (0.67)	1.47 (0.16)	5.30 (0.29)	7.47 (0.41)	88.53 (10.01)	0.40 (0.02)	58.35 (5.25)	37.45 (4.33)
6	13.52 (0.94)	7.95 (0.75)	1.63 (0.65)	5.54 (0.53)	7.70 (0.48)	97.23 (21.70)	0.41 (0.04)	59.02 (6.15)	39.28 (4.90)
11	13.70 (0.95)	8.08 (0.59)	1.75 (0.42)	5.75 (0.52)	7.85 (0.43)	104.80 (10.94)	0.42 (0.03)	59.24 (5.85)	40.39 (4.51)
16	13.92 (0.98)	8.13 (0.61)	1.82 (0.37)	5.88 (0.46)	7.95 (0.38)	109.20 (17.15)	0.42 (0.04)	58.73 (6.46)	41.45 (4.37)
23	14.08 (0.90)	8.21 (0.59)	1.92 (0.65)	6.01 (0.49)	8.07 (0.44)	114.40 (22.60)	0.43 (0.04)	58.56 (5.43)	42.37 (4.44)

Notes: MC is the moisture content (%, d.b.); L is the length (mm); W is the width (mm); T is the thickness (mm); D _g is the geometric mean diameter (mm); D _a is the arithmetic mean diameter (mm); S _p is the sphericity (%); S _a is the surface area (mm²); R _a is the aspect ratio; and V is the volume (mm³). Standard deviations are in parentheses.

Table 2. Equations representing the relation between the axial dimensions (L, W and T) and moisture content for melon seed and its kernel

Melon	MC (%, d.b.)	Equation	R ^2
Seed	2.8–25	L = 13.543 + 0.1613MC − 0.01025MC^2 + 0.0002050MC^3	0.9478
		W = 8.187 + 0.1341MC − 0.00865MC^2 + 0.0001759MC^3	0.9510
		T = 1.4638 + 0.10301MC − 0.005393MC^2 + 0.0000955MC^3	0.9888
Kernel	1.1–23	L = 13.1801 + 0.05902MC − 0.000860MC^2	0.9756
		W = 7.63226 + 0.07427MC − 0.003950MC^2 + 0.00007878MC^3	0.9990
		T = 1.42238 + 0.04428MC − 0.001701MC^2 + 0.0000311MC^3	0.9980

Notes: L is the length (mm), W is the width (mm), T is the thickness (mm) and MC is the moisture content (%, d.b.).

Table 3. Equations representing the relation between the mean diameters, surface area, sphericity, aspect ratio and volume of melon seed and kernel as a function of moisture level

Melon	Moisture content (%, d.b.)	Equation	R ^2
Seed	2.8–25	D g = 5.4119 + 0.1684MC − 0.00925MC^2 + 0.0001662MC^3	0.9733
		D a = 7.7424 + 0.1287MC − 0.00760MC^2 + 0.0001410MC^3	0.9635
		S a = 91.70 + 6.406MC − 0.3518MC^2 + 0.00641MC^3	0.9930
		S p = 0.4219 + 0.001024MC	0.3943
		R a = 60.633 + 0.234MC − 0.0151MC^2 + 0.000315MC^3	0.8520
		V = 39.907 + 1.095MC − 0.0696MC^2 + 0.001397MC^3	0.9676
Kernel	1.1–23	D g = 5.2346 + 0.05942MC − 0.001298MC^2 + 0.0000078MC^3	0.9883
		D a = 7.403887 + 0.0629MC − 0.00253MC^2 + 0.0000460MC^3	0.9997
		S a = 86.055 + 2.248MC − 0.0605MC^2 + 0.000710MC^3	0.9970
		S p = 0.39564 + 0.00381MC − 0.000222MC^2 + 0.00000524MC^3	0.9230
		R a = 58.012 + 0.3157MC − 0.02572MC^2 + 0.000566MC^3	0.8430
		V = 36.992 + 0.4476MC − 0.01418MC^2 + 0.000213MC^3	0.9960

Notes: D _g is the geometric mean diameter (mm), D _a is the arithmetic mean diameter (mm), S _a is the surface area (mm²), S _p is the sphericity, R _a is the aspect ratio, V is the volume (mm³) and MC is the moisture content (%, d.b.).

Table 4a. Mean value and standard deviation of some gravimetric properties of melon seed at different moisture content levels

Moisture content, (d.b. %)	Bulk density (kg/m^3)	True density (kg/m^3)	1000 seed weight (g)	Porosity (%)
2.8	408.04 (2.89)	820.00 (278.75)	43.60 (3.37)	45.27 (2.16)
7	439.20 (2.79)	872.00 (46.74)	107.60 (3.67)	49.26 (2.83)
12	474.10 (1.49)	915.00 (16.86)	118.70 (2.19)	48.17 (0.90)
17	480.00 (4.68)	1125.00 (22.50)	132.30 (1.92)	57.99 (1.70)
25	500.50 (15.68)	1189.00 (129.41)	168.43 (12.95)	57.52 (5.44)

Note: Standard deviation values are in parentheses.

Table 4b. Mean value and standard deviation of some gravimetric properties of melon kernel at different moisture content levels

Moisture content (%, d.b.)	Bulk density (kg/m^3)	True density (kg/m^3)	1,000 seed weight (g)	Porosity (%)
1.1	474.80 (35.02)	1039.40 (31.54)	87.33 (2.65)	54.33 (2.69)
6	490.40 (0.65)	1130.40 (22.46)	91.44 (1.71)	56.61 (0.80)
11	514.80 (0.68)	1172.34 (5.06)	98.11 (0.39)	56.09 (0.14)
16	520.80 (1.55)	1194.70 (29.58)	103.22 (1.84)	56.39 (1.11)
23	539.00 (9.41)	1229.50 (49.50)	105.33 (3.33)	56.12 (1.91)

Note: Standard deviation values are in parentheses.

Table 5. Equations representing the relationship between the gravimetric properties and moisture content of melon seed and its kernel

Melon	MC (%, d.b.)	Equation	R ^2
Seed	2.8–25	ρ b = 385.49 + 8.96MC − 0.1771MC^2	0.9323
		ρ t = 753.5 + 18.08MC	0.9267
		S 1,000 = −21.4 + 28.68MC − 1.858MC^2 + 0.0406MC^3	0.9570
		$p=45.66-\frac{0.2936}{(1-0.07766\text{MC})}+0.5329\text{MC}$	0.6570
Kernel	1.1–23	ρ b = 469.46 + 4.324MC − 0.0577MC^2	0.9545
		ρ t = 1010.73 + 27.95MC − 1.556MC^2 + 0.03280MC^3	0.9990
		K 1,000 = 86.775 + 0.357MC + 0.0951MC^2 − 0.003288MC^3	0.9980
		p = 53.690 + 0.721MC − 0.0558MC^2 + 0.00127MC^3	0.5110

Notes: ρ _b is the bulk density (kg/m³); ρ _t is the true density (kg/m³); S _1,000 is the 1,000 seed weight (g); P is the porosity (%); and MC is the moisture content (%, d.b.).

Table 6a. Mean value and standard deviation of some frictional properties of melon seed at different moisture content levels

MC (%, d.b.)	Angle of repose (°)		Static coefficient of friction on structural surfaces
	Filling	Funnelling	Plywood	Rubber	Galvanized sheet	Foil
2.8	20.67 (0.09)	30.73 (1.05)	0.46 (0.00)	0.36 (0.00)	0.37 (0.01)	0.40 (0.00)
7	27.25 (1.18)	50.12 (0.33)	0.54 (0.01)	0.41 (0.01)	0.39 (0.01)	0.44 (0.01)
12	32.34 (0.21)	54.49 (0.72)	0.56 (0.01)	0.41 (0.02)	0.40 (0.01)	0.46 (0.01)
17	38.58 (0.61)	55.85 (0.69)	0.60 (0.01)	0.44 (0.02)	0.41 (0.02)	0.48 (0.00)
25	40.66 (0.89)	57.35 (0.58)	0.67 (0.00)	0.44 (0.00)	0.43 (0.00)	0.49 (0.00)

Notes: MC is the moisture content (%, d.b.); Standard deviations are in parentheses.

Table 6b. Mean value and standard deviation of some frictional properties of melon kernel at different moisture content levels

MC (%, d.b.)	Angle of repose (°)		Static coefficient of friction on structural surfaces
	Filling	Funnelling	Plywood	Rubber	Galvanized sheet	Foil
1.1	30.52 (0.45)	45.62 (1.01)	0.52 (0.01)	0.45 (0.01)	0.51 (0.03)	0.47 (0.01)
6	33.45 (0.05)	63.06 (0.37)	0.64 (0.02)	0.58 (0.03)	0.53 (0.01)	0.53 (0.01)
11	34.07 (1.19)	65.89 (0.34)	0.67 (0.01)	0.63 (0.01)	0.54 (0.01)	0.56 (0.01)
16	36.14 (0.37)	67.03 (0.56)	0.68 (0.01)	0.67 (0.01)	0.57 (0.01)	0.61 (0.01)
23	38.04 (0.23)	67.19 (1.06)	0.70 (0.01)	0.69 (0.00)	0.59 (0.01)	0.65 (0.00)

Notes: MC is the moisture content (d.b., %); Standard deviations are in parentheses.

Table 7. Equations representing the relationship between the frictional properties and moisture content of melon seed and its kernel

Melon	Moisture content (%, d.b.)	Equation	R ^2
Seed	2.8–25	Fia = 15.45 + 1.921MC − 0.03616MC^2	0.9600
		Fua = 10.56 + 8.77MC − 0.545MC^2 + 0.01077MC^3	0.9650
		S pw = 0.3899 + 0.0307MC − 0.00178MC^2 + 0.0000400MC^3	0.9590
		S rub = 0.3415 + 0.00923MC − 0.000212MC^2	0.8210
		S gs = 0.35155 + 0.00779MC − 0.00041MC^2 + 0.0000090MC^3	0.9982
		S fl = 0.37769 + 0.00950MC − 0.0002012MC^2	0.9810
Kernel	1.1–23	Fia = 18.64 + 1.643MC − 0.02918MC^2	0.9840
		Fua = 24.39 + 6.381MC − 0.4225MC^2 + 0.00902MC^3	0.9850
		S pw = 0.4376 + 0.02343MC − 0.001472MC^2 + 0.0000389MC^3	0.9877
		S rub = 0.3555 + 0.00821MC − 0.000197MC^2	0.8470
		S gs = 0.36404 + 0.00588MC − 0.000324MC^2 + 0.0000084MC^3	0.9990
		S fl = 0.39258 + 0.008334MC − 0.0001789MC^2	0.9965

Notes: Fia is the filling angle of repose (°); Fua is the funnelling angle of repose (°); S _pw is the static coefficient of friction on plywood surface; S _rub is the static coefficient of friction on rubber surface; S _gs is the static coefficient of friction on galvanized sheet surface; and S _fl is the static coefficient of friction on foil surface.