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Thai Journal of Agricultural Science 2010, 43(2): 97-101
Physical Properties of Nectarine Fruit (cv. Sunking) to Characterize Best Post Harvesting Options J. Tarighi1,*, S.S. Mohtasebi1, H. Heydari1 and M. Abasghazvini2 1
Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Karaj, Iran 2 Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering, University of Tabriz, Iran *Corresponding author. Email:
[email protected]
Abstract In this study, several physical and hydrodynamic properties of nectarine fruit cv. Sunking are presented. The measured physical properties included: average fruit length, width, thickness, projected area, face surface area, sphericity index, aspect ratio, fruit mass, moisture content and volume. The terminal velocity of the fruit, dropping time and bouncy and drag forces were 0.11 m s-1, 9.6 s, 0.67 N, 0.70 N, respectively. Packing coefficient was 0.65. The measured data can be used to design equipment for harvesting, transporting, hydraulic sorting, sizing and packing of nectarine fruit. Keywords: sphericity index, bouncy force, drag force, terminal velocity
Introduction Since electrical sizing mechanisms are very expensive and mechanical sizing mechanisms are slow to react (Tabatabaeefar and Rajabipour, 2005), recently researchers have been more interested in hydraulic sorting of fruits and vegetables. Sorting fruits based on density, as dry matter indicator, is a proper method in quality sorting of fruits because of its low cost and simple operation (Richard et al, 1997; Jordan et al, 2000). Terminal velocity is an important characteristics parameter in the pneumatic conveying systems and machinery design such as strippers. It is a constant speed that a material can reach in a fluid. According to Jordan and Clerk (2004) studies, an approach of quality sorting of fruits is to use the terminal velocity of fruit moving in a fluid that has a density above or below the fruit density. Fruits with different densities will reach different depths at fixed time durations and may be separated by suitably placed dividers. In this approach, water can be used as a proper environment for sorting fruits
due to its less damage and easy access. Also the settings required in this approach consist of only mechanical settings, means adjusting just divider’s position. Generally, it seems terminal velocity is a complicated function of difference between water and fruit densities, fruit shape, size and volume. Nectarine fruit is a kind of peach which was created due to a mutation in one of peach genes. As a result of this mutation, peach fuzzy skin became smooth and special color, odor and taste appeared in new fruit. This mutation is reversible and it is possible to reconvert nectarine to peach (khoshkhouy et al., 1985). In this study, several physical and hydrodynamic properties of nectarine fruit which are effective in hydraulic sorting systems are investigated. The Determination of physical and mechanical properties of agricultural products is of great importance in designing sorting, sizing, transporting, processing and packing machines (Tabatabaeefar and Rajabipour, 2005; Tavakoli et al, 2009; Tavakoli et al, 2010). According to previous researches, mass, volume, projected area
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and center of gravity have high importance in defining system dimensions (Peleg and Ramraz, 1975; Khodabandehloo, 1999). The quality difference between fruits can be determined by their densities. Determining fruit projected area and exact volume is necessary in designing dryer systems or hydraulic conveying of fruits (Peschel et al., 2007). It is useful to find the relationship between fruit projected area, dimensions and mass for its sizing or mass sorting (Wright et al., 1986). In hydraulic transporting of fruits, hydrodynamic properties of the fluid are of high importance. According to Mohsenin (1986), fluid velocity in hydraulic transporting of fruits depends on fruit terminal velocity and the dimensions of the channel in which fruit will move:
ve Where: ve = vt = d = Rh =
= vt [
1 4 Rh ] 2 d
(1)
Thai Journal of Agricultural Science
measured using a digital balance with 0.1 g accuracy. The diameters were obtained from the equations (2), (3) and (4) (Mohsenin, 1986): 1
D g = (LDT ) 3 D p = [L Da
=
(W +T ) 2 13 ] 4
( L +W +T ) 3
(2) (3) (4)
Where: Dg = geometric diameter (mm) Dp = equivalent diameter (mm) Da = arithmetical diameter (mm) Sphericity was obtained from equation (5) (Mohsenin, 1986): 1
-1
flow velocity (m s ) terminal velocity of the fruit (m s-1) diameter of the channel hydraulic radius of the channel
In order to design and manufacture fruits sorting and sizing equipments, it is necessary to determine the terminal velocity and density of the fruits (Matthews et al., 1965; Dewey et al., 1966). Jordan and Clark (2004) reported that when fruits get released in water from a specified height, in case they have different densities, they can be sorted based on their terminal velocity differences. Kheiralipour et al. (2008) investigated terminal velocities of two varieties of apple. They used a glass column with specified dimensions and a digital camera to determine terminal velocity of the apples. Materials and Methods From the samples, 30 Nectarine fruits cv. Sunking were selected randomly then to determine the moisture content. The samples were left in an oven at 77°C for 10 days (Masoudi et al., 2004). Rests of the tests were done at room temperature (22°C). The fruit dimensions including length (L), width (W) and thickness (T) were measured using a caliper with 0.1 mm accuracy. The fruit mass was
Sp =
( LDT ) 3 L
(5)
Fruit face Surface area was measured using following equation: S
= π (Dg )2
(6)
Equation (7) was used to obtain aspect ratio (Ra):
Ra =
W L
(7)
To measure fruit volume and density, water displacement method was used (Mohsenin, 1986). The projected area of the fruit was measured using area measurement system; Delta Tengland, shown in Figure 1. Packing coefficient was obtained using equation (8) (Topuz et al., 2004):
λ
=
V Vo
Where: λ = packing coefficient V = true volume of fruit Vo = volume of the box containing fruits
(8)
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Best post harvesting options of nectarine fruit
To determine the terminal velocity of the fruit, a Scaling glass column with 1.40 m height and 400×400 mm cross section was used which was filled with water to a height of 1.20 m. These dimensions were specified according to Vanoni’s researches (1975) that fruit diameter must be 20% of the tank diameter. A digital camera, JVC with 25 frames per second, recorded the movement of fruits from releasing point to the top of the water column, simultaneously (Figure 3). Each fruit was tested three or four times. Video to frame software was used to convert the video film to individual images and, subsequently, to calculate coming up times and terminal velocities of fruits by knowing the fact that each picture takes 0.04 s. The total time of fruit moving inside water was also recorded. Figure 2 illustrates the tank and he process of the test.
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Drag and Bouncy forces, the forces for and against fruit movement in water, were calculated using equations (9) and (12):
F d = C d Ap Where: λ = Fd = Ap = ρf = Cd = V =
ρ fV 2 2
packing coefficient drag force (N) projected area (cm2) fruit density (kg m-3) drag coefficient (N) terminal velocity of the fruit (ms-1)
Cd can be obtained using equations below: Cd =
24 NR
(10)
NR =
V .D v
(11)
F b = ρ f .V . g Where: NR = D = Fb = v = g =
Figure 1 Fruit projected area measurement system.
(9)
(12)
Reynolds’ number fruit diameter (mm) bounce force (N) dynamic viscosity of water acceleration of gravity (ms-2)
Results and Discussion A summary of measured physical and hydrodynamic properties of nectarine is given in Table 1. The moisture content of nectarine cv. Sunking was 0.83. Average fruit length, width and thickness were 92.51, 98.48 and 25.64 mm, respectively. Packing coefficient, volume and density of nectarine fruit were measured as 0.72 cm3, 0.67 cm3 and 1017.52 kg m-3. According to Topuz et al. (2004), packing coefficient decreases with increased fruit volume, due to the vacancy left among the fruits. In this research, packing coefficient seems to be sensible as a result of low volume of nectarine fruit.
Figure 2 Water column and camera setting to the side
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Table 1 Several physical and hydrodynamic properties of nectarine fruit cv. Sunking.
Measured parameter
Standard deviation ± mean
Minimum
Maximum
Length (mm)
51.92 ± 6.98
35.78
64.88
Width (mm)
48.98 ± 2.01
34.6
58.52
Thickness (mm)
46.25 ± 3.91
34.4
54.34
Geometric mean diameter (mm)
48.97 ± 2.67
34.92
57.34
Equivalent diameter (mm)
48.98 ± 4.47
34.9
62.32
Arithmetic diameter (mm)
49.05 ± 6.47
34.92
62.35
0.94 ± 0.02
0.88
0.98
Sphericity (%) 2
Surface area (mm ) 2
Projected area (mm ) Aspect ratio Fruit mass (gr) Density (kg m-3)
7186.19 ± 628.29
3829.24
10291.4
2779.23 ± 725.8
1481.9
4208.6
0.94 ± 0.04
0.84
0.99
64.26 ± 11.02
25.79
122.82
1017.52 ±52.19
987.7
1031.03
Moisture content (%)
0.83 ± 0.04
0.71
0.9
Packing coefficient
0.65 ± 0.02
0.64
0.67
Terminal velocity (m s-1)
0.11 ± 0.041
0.06
0.22
Dropping time (s)
9.6 ± 3.11
6
Drag force (N)
0.07 ± 0.008
0.04
0.16
Bouncy force (N)
0.67 ± 0.26
0.25
1.34
The terminal velocity of nectarine fruit was an important parameter investigated in this research. For that, 30 nectarine fruits were released in water column filled with water to 120 cm height, at room temperature and water zero initial velocity, shown in Figure 2. Due to higher density of samples compared to water, they moved to bottom of the column. The average terminal velocity of nectarine fruit was calculated as 0.11 m s-1. Kheiralipour et al. (2009) investigated the terminal velocity of two apple cultivars named Redspar and Delbarstival. They reported that due to lower density of apples compared to water, both apple cultivars moved up in the water column when placed at the bottom. To place the fruit in bottom of the column, they used a clamp with a long handle. The terminal velocities they calculated were 0.47 and 0.42 m s-1, which are higher than terminal velocity of nectarine cv. Sunking. This can be the result of low density difference between nectarine and water, compared to the density difference between apple and water. Mirzaee et al. (2009) calculated the terminal velocity of apricot. The average terminal velocity
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they reported was 0.17 m s-1. Compared to nectarine, the difference between nectarine and apricot terminal velocity is low which result of their close density is.
Figure 3 The positions of nectarine fruit in water column; while being released (a), 5.02 seconds after being released (b), and 7.42 seconds after being released (c).
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Best post harvesting options of nectarine fruit
Conclusions Some engineering properties of nectarine fruit (cv. Sunking) witch may be useful in designing much of the equipment used for harvest and postharvest processing were studied in this paper. Authors concluded that the terminal velocity of fruits is a good property of fruits for sorting. Authors also suggest that it is better for fruits that are sensitive to mechanical sorting, is better to use the hydraulic sorting. Acknowledgments The authors would like to thank the University of Tehran for providing the laboratory facilities and financial support for this project. The authors are also grateful to Mahdi Ghasemi and Kamran kheiralipor for their helps. References Khoshkhouy, M. B. Sheibani, A. Roohani and A. Tafzili. 1985. Horticulture Principals, 2nd ed. Shiraz University Publications. Masoudi, H. A. Tabatabaeefar and A. Borghei. 2004. Investigation of Mechanical Properties Variation of Three Export Varieties of Apples Alluring the Storage. M.S. Thesis, University of Tehran, Karaj, Iran. Khodabandehloo, H. 1999. Physical Properties of Iranian Export Apples. M.S. Thesis, University of Tehran, Karaj, Iran. Dewey, D.H., B.A. Stout, R.W. Matthews and F.W. Bekker-Arkema. 1966. Developing of hydrohandling system for sorting and sizing apples for storage in pallet boxes. USDA, Marketing Research Report. 743 SDT, UDFS. Jordan, R.B., E.F. Walton, K.U. Klagesand R.J. Seelye. 2000. Postharvest fruit density as an indicator of dry matter and ripened soluble solids of kiwifruit. Postharvest Biological Technology 20: 163-173.
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Jordan, R.B. and C.J. Clark. 2004. Sorting of kiwifruit for quality using drop velocity in water. ASAE. 47: 1991-1998. Kheiralipour, K., A. Tabatabaeefar, H. Mobli, S. Rafiee, M. Sharifi, A. Jafari and A. Rajabipour. 2008. Some physical and hydrodynamic properties of two varieties of apple (Malus domestica Borkh L.) Int. Agrophysics 22: 225-229. Matthews, R.W., B.A. Stout, D.D. Dewey and F.W. Bekker-Arkema. 1965. Hydrohandling of apple fruits. ASAE. Mirzaee, E., S. Rafiee, E. Keyhani and Z. Djomeh. 2009. Physical properties of apricot to characterize best post harvesting options. Aust. J. Crop Sci. 2: 95-100. Mohsenin, N.N. 1986. Physical Properties of Plant and Animal Materials. Gordon and Breach Press, New York. Peleg, K. and Y. Ramraz. 1975. Optimal sizing of citrus fruit. ASAE. 18: 1035-103 Peschel, S., R. Franke, L. Schreiber and M. Knoche. 2007. Composition of cuticle of developing sweet cherry fruit. Phytochemistry 68: 1017-1025 Richard, A.C., K.J. McAneney and T.E. Dawson. 1997. Carbohydrate dynamics in kiwifruit. J. Hort. Sci. 72: 907-917. Tabatabaeefar, A. and A. Rajabipour. 2005. Modeling the mass of apples by geometrical attributes. J. Hort. Sci. 105: 373-382. Tavakoli, H., S.S. Mohtasebi, V.M. Ghasemi and M. Tavakoli. 2010. Some physical, mechanical and thermal properties of barley (Hordeum vulgare L.) grains. Food Sci. Tech. Int. (in press). Tavakoli, H., S.S. Mohtasebi, A. Rajabipour and M. Tavakoli. 2009. Effects of moisture content, loading rate, and grain orientation on fracture resistance of barley grain. Res. Agric. Eng. 55: 85-93. Topuz, A., M. Topakci, M. Canakci, I. Akinci and F. Ozdemir. 2004. Physical and nutritional properties of four orange varieties. J. Food Eng. 66: 519-523. Vanoni, V.A. 1975. Sedimentation Engineering. ASCE Manual, ASCE Press, New York. Wright Malcolm, E., J.H. Toppan and F.E. Sister. 1986. The size and shape of typical sweet potatoes. ASAE. 29: 678-682. Manuscript received 11 February 2010, accepted 1 October 2010
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