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Author(s) First Name
Middle Name
Mohammad
Surname
Role
Email
Loghavi
ASABE Member
[email protected]
Affiliation Organization
Address
Country
Agricultural Engineering Dept.
Shiraz University, Shiraz
Iran
Author(s) – repeat Author and Affiliation boxes as needed-First Name
Middle Name
Surname
Saman
Souri
Dariush
Zare
Farzaneh
Khorsandi
Role
Email
Affiliation Organization
Address
Country
Agricultural Engineering Dept.
Shiraz University, Shiraz
Iran
Agricultural Engineering Dept.
Shiraz University, Shiraz
Iran
Agricultural Engineering Dept.
Shiraz University, Shiraz
Iran
Publication Information Pub ID
Pub Date
10
2010 ASABE Annual Meeting Paper
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2010. Title of Presentation. ASABE Paper No. 10----. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
[email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
An ASABE Meeting Presentation Paper Number: 10
Some Physical and Mechanical Properties of Estahban Edible Fig (Ficus Carica cv. Sabz) M. Loghavi Professor, Ag. Engineering Dept., Shiraz University, Shiraz, Iran,
[email protected]
S. Souri Graduate student, Ag. Engineering Dept., Shiraz University, Shiraz, Iran
D. Zare Assistant professor, Ag. Engineering Dept., Shiraz University, Shiraz, Iran,
[email protected]
F. Khorsandi Graduate student, Ag. Engineering Dept., Shiraz University, Shiraz, Iran
Written for presentation at the 2010 ASABE Annual International Meeting Sponsored by ASABE David L. Lawrence Convention Center Pittsburgh, Pennsylvania June 20 – June 23, 2010 Mention any other presentations of this paper here, or delete this line.
Abstract. Knowledge of the physical properties of edible fig fruit is necessary for design of shake harvesting and postharvesting processes such as drying, sorting, grading, and packing. In this study, some moisture and ripeness dependent physical and mechanical properties of Estahban edible fig (Ficus carica cv. Sabz) were determined. The properties measured included, geometric, gravitational and frictional attributes at two levels of naturally dried fruits (left on the tree and dropped on the ground), four levels of ripeness based on moisture content and two levels of unripe fruits at two moisture content. The geometric properties included, dimensions in three perpendicular directions, geometric and arithmetic mean diameters and sphericity. The gravitational properties included, mass, volume, bulk density, true density and porosity. The frictional properties included angles of static friction and rolling resistance on wood, galvanized steel and rubber belt. Average moisture contents of the ripe fruits classified into six ripeness categories were 20.6, 23.6, 39.4, 41.8, 54 and 70 percent and those of unripe fruits in two categories were 69.5 and 76 percent on wet basis, The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2010. Title of Presentation. ASABE Paper No. 10----. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
[email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
respectively. Geometric dimensions, sphericity, mass, volume, bulk density and porosity of all ripe categories increased, while those of unripe fruits decreased with increasing moisture content. Angle of static friction was lowest on galvanized steel and highest on rubber belt, while angle of rolling resistance was highest on galvanized steel and lowest on rubber belt. Keywords. Figs, Physical properties, Moisture content, Friction angle.
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural and Biological Engineers (ASABE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASABE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASABE meeting paper. EXAMPLE: Author's Last Name, Initials. 2010. Title of Presentation. ASABE Paper No. 10----. St. Joseph, Mich.: ASABE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASABE at
[email protected] or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA).
Introduction Dried figs are the fruit of the tree “Ficus Carica” from which the greater portion of moisture has been removed. Figs comprise a large genus, Ficus, of deciduous and evergreen tropical and subtropical trees, shrubs, and vines belonging to the mulberry family Moraceae. It has been cultivated as a fruit tree in eastern Mediterranean Sea, Europe, Africa and south West Asia since long ago. Nowadays, figs are cultivated in many parts of the world like tropical and semi tropical areas. Iran with annual production of 8800 tones is the third largest fig producer in the world after Egypt (304000 tones) and Turkey (205000 tones) (FAO, 2008). Modern agriculture has brought about the handling and processing of plant and animal materials by various means such as mechanical, thermal, electrical, optional and even sonic techniques and devices. Despite these ever increasing applications, little is known about the basic physical characteristics and properties of these materials (Mohsenin, 1986). In order to perform postharvest processes like grading, sorting, drying, and packing, some physical properties of figs are necessary to be known. The most important physical properties are size, shape, roundness, volume, color, appearance, sphericity, density, porosity and static and dynamic coefficients of friction. Fig size and shape characteristics are necessary for removing debris and other undesirable materials mixed with the dried fruits and also in sorting and grading machinery. Bulk density and porosity which affect the resistance to air flow of stored mass (Bern and Charity, 1975) are major factors in designing driers and aeration systems. Bulk density and coefficient of friction are considered as basic parameters for prediction of the structural loads in storage bins (Lvin, 1970) and they affect the lateral and vertical wall pressures in bin storages (Shamlou, 1988). Many researchers have investigated the effect of moisture content on some physical properties of different agricultural products. The materials studied include raw cashew nut (Balasubramanian, 2001), Areca nut kernels (Kaleemullah and Gunasekar, 2002), Hacihaliloglu apricot pit and kernel (Gezer et al., 2002), hazel nut (Aydin, 2002), pistachio nut and its kernel (Razavi, 2007). Scientists have investigated some physical properties of different agricultural products. Cumin seed (Singh and Goswami, 1996), Terebinth fruits (Aydin and Ozcan, 2002), Locust bean seed (Ogunjimi et.al. , 2002), Pigeon pea ( Baryeh and Mangope, 2002), millet (Baryeh,2002), ground nut kernels (Olagide and Igbeka, 2003), almond nut and kernel ( Aydin, 2003), Category B cocoa beans (Bart-Plange and Baryeh, 2003), edible squash seeds (Paksoy and Aydin, 2004), cherry laurel ( Calisir and Aydin, 2004), Egyptian onion cultivars (Bahnasawy et.al., 2004), fresh okra fruit ( Owolarafe and Shotonde, 2004), Amaranth seeds ( Abalone, 2004), gumbo fruit varieties ( Akbar and Aydin , 2004), edible micronised lentils ( Scanlon et al., 2005), African star apple (Oyelade et al., 2005), wild plum ( Calisir et al., 2005) are some of the products which has been investigated.
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Yeshajahu and Mclon (1987) used the toluene distillation method to determine the initial moisture content of raw cashew nut. Ismail and Alyahya (2003) introduced a quick method for measuring dates moisture content using a simple and inexpensive electronic circuit. Razavi et al., 2008 investigated the physical, frictional and aero dynamical properties of two types of dried figs (opened husk and closed husk) at 34.95 % w.b. moisture content. It seems there is no published work relating to moisture dependent properties of Estahban dried figs. Therefore, this study was conducted to investigate some physical properties of Estahban Edible Fig (Ficus Carica L. cv. Sabz) during final stages of ripening and natural drying on the tree before harvesting.
Materials and Methods The figs used in this research were harvested either by hand or by a limb shaker from Estahban valley in Fars province of Iran. The harvested figs were divided into 8 groups based on their moisture content and were kept in separated polythene bags in refrigerator at about 4˚C before testing. The amount of figs which was used for testing in a day was removed from refrigerator about four hours before each test to achieve room temperature (Owolarafe and Shotonde, 2004). Moisture content Moisture content is an important property in harvesting, sorting, marketing and processing of figs. The initial moisture content of each group was determined using the oven method (AOAC, 1995) and was found to vary from 20.5% to 76%. The moisture contents were expressed in wet basis (w.b.). Geometric properties From each group, samples of 100 figs were randomly selected to measure their three principle dimensions named as; major diameter (a), medium diameter (b) and minor diameter (c). Dimensions were precisely measured with a vernier caliper reading to 0.005 mm accuracy. By knowing these dimensions, geometric mean diameter, arithmetic mean diameter, sphericity, surface area and shape index were calculated using the following formulas (Mohsenin, 1986; Bahnasawy, 2004 and Dursun and Dursun, 2005). Geometric mean diameter (Dg)
D g (a.b.c)
1
3
[1]
Arithmetic mean diameter (Da) Da (
abc ) 3
[2]
Sphericity (Φ)
3
(a.b.c) a
1
3
[3]
Surface area (S)
S D g
2
[4]
Shape index Shape index is the quantity used to represent the shape of figs and it is calculated according to the following equation (Abd Alla, 1993 and Bahnasawy, 2004). Shape index
a b.c
[5]
The shape of a fig is assumed oval if the shape index > 1.5 and it is spherical if the shape index < 1.5 (Abd Alla, 1993 and Bahnasawy, 2004). Mass The mass of 100 figs, randomly selected from each group were measured with an electrical balance having accuracy of 0.01 (Balasubramanian, 2001). Density To determine the true density (ρt) of figs as a function of moisture content, each fig was weighed and dropped separately in toluene. By liquid displacement method the real density was calculated. Toluene (C7H8) was used rather than water because it is absorbed to a lesser extent, its dissolution power is low and also, its surface tension is low, so that it fills even shallow dips in a fig (Mohsenin, 1986; Singh & Goswami, 1996 and Gezer et al., 2002). Bulk density (ρb) was determined by use of a container having a definite volume and filling it by figs. The figs were poured into container from a height of 15 cm and excess figs were removed without applying any compaction. The bulk density is the ratio of the mass of sample to its total volume (Aydin, 2002). After filling the container it was weighed to gain the mass of figs. These steps were repeated 10 times for each moisture group. Porosity The porosity was determined by the following equation:
(1
b ) * 100 t
[6]
4
Where, ρb and ρt are the bulk and true density, respectively (Mohsenin, 1986; Gezer, et al., 2002 and Owolarafe and Shotonde, 2004). Static coefficient of friction The static coefficient of friction of figs with different moisture content was determined with a friction device, on wood, rubber and galvanized steel sheet. For this measurement one end of the friction surface is attached to an endless screw. The figs were placed on the surface in a bottomless box to prevent rolling of figs and also the box didn’t touch the surface. The surface was gradually raised by the screw (Baryeh, 2001; Gezer et al., 2002 and Owolarafe and Shotonde, 2004). The angle of the surface was reported as angle of static friction. The tangent value of this angle was reported as static coefficient of friction. Rolling angle Determining rolling angle was similar to determining static coefficient of friction with this exception that each fig was separately placed on the surface from its most stable position (Bahnasawy et al., 2004). The angle of the surface in which fig started to roll was considered as the rolling angle.
Results and Discussions Dimensions The results of measuring three principle dimensions are given in table 1. As the moisture content increased from 20.5% to 76%, the average dimensions increased except for groups 7 and 8 which are unripe and behave differently. Kaleemullah and Gunasekar (2002) have reached the same results for Areca nut kernels. The geometric and arithmetic mean diameters of the ripped figs (groups 1 to 6) represented as polynomial and linear functions of moisture content are shown in figures 1 and 2, respectively. These two figures show that geometric and arithmetic diameters both follow almost the same trend with regard to moisture content. This due to the fact that fully ripped figs shrink progressively as they lose their moisture content and dry up naturally on the fruit bearing branches. The opposite trend of changing fruit dimensions with moisture content in the case of unripe figs (groups 7 and 8) could be attributed to continued growth of fruit size as fruits approach to the final stage of ripening at about the moisture content of group 7.
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Table 1. Mean values of fig’s principal dimensions (standard deviation in parentheses). Moisture content
Axial dimensions, cm
%w.b.
1
20.56
2
23.58
3
39.43
4
41.83
5
54.03
6
70.23
7
69.52
Geometric diameter, cm
8
75.98
Medium diameter
Minor diameter
Arithmetic
Geometric
(a)
(b)
(c)
( Da )
( Dg )
2.440
2.238
2.176
2.285
2.279
(0.210)
(0194)
(0218)
2.454
2.257
2.171
2.294
2.287
(0179)
(0.219)
(0.221)
2.536
2.293
2.145
2.306
2.295
(0.207)
(0.180)
(0.182)
2.514
2.247
2.239
2.333
2.326
(0.204)
(0.245)
(0.217)
2.551
2.421
2.124
2.365
2.354
(0.176)
(0.188)
(0.275)
2.864
2.605
2.351
2.607
2.592
(0.283)
(0.210)
(0.252)
2.934
2.748
2.405
2.696
2.684
(0.256)
(0.227)
(0.247)
2.321
2.078
2.061
2.153
2.149
(0.211)
(0.210)
(0.180)
y = 0.0002x2 - 0.0118x + 2.4493 R2 = 0.9709
2.70 2.60 2.50 2.40 2.30 2.20 0
10
20
30
Mean diameter, cm
Major diameter
40
50
60
Moisture content (w.b.)
70
80
Geometricdiameter, cm
Group number
y = 0.0056x + 2.1234 R2 = 0.7517
2.70 2.60 2.50 2.40 2.30 2.20 0
10
20
30
40
50
60
70
80
Moisture content (w.b.)
6
y = 0.0002x2 - 0.0116x + 2.4522
2.70
2
R = 0.9735
2.60 2.50 2.40 2.30 2.20 0
10
20
30
40
50
60
70
80
Moisture content (w.b.)
Arithmetic diameter, cm
Arithmetic Diameter,cm
Figure 1. Geometric mean diameter as a function of moisture content.
y = 0.0058x + 2.1259 R2 = 0.7631
2.70 2.60 2.50 2.40 2.30 2.20 0
10
20
30
40
50
60
70
80
Moisture content (w.b.)
Figure 2. Arithmetic mean diameter as a function of moisture content. Surface area, Sphericity and Shape index The mean values of surface area, sphericity and shape index calculated for each moisture content group are given in table 2. The mean values of surface are, sphericity and shape index of the ripped figs (groups 1 to 6) represented as polynomial and linear functions of moisture content are shown in figures 3, 4 and 5, respectively. Progressive reduction of surface area at lower moisture content as shown in figure 3 is due to fruit shrinkage and reduction of their overall dimensions as fruits dry up naturally on the fruit bearing branches. Here again, the trend is reverse in case of the unripe fruits (groups 7 and 8) due to the same reasons mentioned in the preceding section. The high sphericity (mean values close to unity) and the shape index for all groups well below 1.5 indicates that we can assume the shape of fig fruits closer to spherical than oval. Figures 4 and 5 both show that fruit shapes become more spherical as ripe fruits dry up and lose their moisture content.
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Table 2 .Surface area, sphericity and shape index (standard deviation in parentheses)
Group number
Moisture Content (%w.b.)
Surface Area
20.56
1
2
23.58
3
39.43
4
41.83
5
54.03
6
69.52
7
70.23
75.98
23
y = 0.0855x + 14.011
21
R2 = 0.7426
19 17 15 0
20
40
Shape Index
16.413
0.936
1.110
(0.516)
(0.048)
(0.095)
16.514
0.933
1.114
(2.347)
(0.042)
(0.082)
16.627
0.907
1.146
(2.076)
(0.045)
(0.089)
17.100
0.926
1.126
(2.732)
(0.041)
(0.079)
17.492
0.923
1.131
(2.505)
(0.039)
(0.074)
21.207
0.909
1.162
(2.912)
(0.053)
(0.114)
22.757
0.916
1.144
(3.610)
(0.031)
(0.062)
14.611
0.927
1.123
(2.485)
(0.027)
(0.051)
Surface area, cm2
Surface area, cm2
8
Sphericity
2
(cm )
60
Moisture content (w.b.)
80
y = 0.0031x2 - 0.1857x + 19.103 R2 = 0.9692
23 21 19 17 15 0
20
40
60
80
Moisture content (w.b.)
Figure 3. Mean values of fig’s surface area as a function of moisture content.
8
y = 8E-06x2 - 0.0012x + 0.9551 R2 = 0.564 0.94
0.93
Sphericity
Sphericity
0.94
y = -0.0005x + 0.9423 R2 = 0.5311
0.92 0.91 0.9
0.93 0.92 0.91 0.9
0
10
20 30
40
50
60 70
80
0
Moisture Content (w.b.)
10
20
30
40 50
60
70
80
Moisture Content (w.b.)
1.17 1.16 1.15 1.14 1.13 1.12 1.11 1.10
y = 1E-06x2 + 0.0008x + 1.0946 R2 = 0.7532
0
10
20
30
40
50
60
Moisture Content (w.b.)
Shape Index
Shape Index
Figure 4. Mean values of fig’s sphericity as a function of moisture content.
70
80
y = 0.0009x + 1.093
1.17 1.16 1.15 1.14 1.13 1.12 1.11 1.10
R2 = 0.753
0
10
20
30
40
50
60
70
80
Moisture Content (w.b.)
Figure 5. Mean values of fig’s shape index as a function of moisture content.
Statistical analysis Analysis of variance and mean comparison on geometric property data show that all geometric data measure in this study including, length, width, thickness and other calculated dimensional properties significantly change with changing fruit moisture content. The results of mean comparison using Duncan’s multiple range test (p
