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Acta Agroph., 2017, 24(2), 217-223
DETERMINATION OF SOME PHYSICAL PROPERTIES
OF DATE PALM FRUITS (CV. KHADRAWY AND MEDJOOL)
Manoj Kumar Mahawar1, Kirti Jalgaonkar1, Mukesh Kumar2, Vijay Singh Meena1,
Bharat Bhushan1
1Horticultural Processing Division, ICAR – Central Institute of Post-Harvest Engineering & Technology
Abohar, Punjab-152116, India
2College of Agricultural Engineering and Technology, HAU Hisar, Haryana, India
e-mail: manojmahawar362@gmail.com
A b s t r a c t. The present investigation was carried out to evaluate some physical properties of date
palm fruits cv. Khadrawy and Medjool. Pulp moisture content, seed moisture content, fruit dimen-
sions (Major and minor intercept), arithmetic mean diameter, geometric mean diameter, sphericity,
colour values (L, a, b), bulk density, true density, porosity and coefcient of static friction were
determined for both the varieties. The determined properties had signicant difference in their values
which may be due to the distinctive features of both the varieties.
K e y w o r d s: date palm, physical properties, Khadrawy, Medjool
INTRODUCTION
Date palm (Phoenix dactylifera L.) is one of the oldest fruit crops of the arid regions of
Arabian Peninsula, North Africa and the Middle East. They are considered to be a major
source of income as well as staple food for the local population in the countries where
they are cultivated (Chao and Krueger, 2007). Dates contain dietary bre, pectin, tannins,
some vitamins, minerals, low quantities of organic acids, with very little or no starch, and
a number of antioxidant anti-mutagenic compounds (Biglari et al. 2008). Because of its
nutritional properties, date fruit as such can have an extensive range of applications, but
at present the processing applications are very limited (Kamal-Eldin et al. 2012).
The knowledge of some important physical properties such as spatial dimensions,
bulk density, true density, and porosity of different fruits/vegetables/grains is essential for
the design of storage structures, processing equipments, and processes (Vishwakarma et
al. 2012). Linear dimensions and colour values are required especially for the design
of equipments related to sorting and grading. Estimation of bulk density is required to
M.K. MAHAWAR et al.
218
determine the capacity of storage and transport, while the true density is useful to design
proper separation equipment. Porosity of the fruit mass determines the resistance to air-
ow during aeration and drying operations. Information about the frictional properties is
essential to understand the behaviour of the fruits during handling operations and for the
design of handling equipments (Jahromi et al. 2008). Varietal difference of fruits is also
one of the prominent reasons for having deviations in physical properties.
There are plentiful studies which include the determination of physical properties of
different fruits with varietal differences. Few among them include ve date cultivars, viz.
Gash Gaafar, Gash Habash, Shahla, Bushibal and Lulu (Al- Hooti et al. 1997), mango cv.
Dashehari (Jha et al. 2006), three sweet cherry varieties (Prunus avium L.) (Vursavus et
al. 2006), guna fruits (Aviara et al. 2007), date fruit cv. Lasht (Jahromi et al. 2007), date
fruit cv. Dairi (Jahromi et al. 2008) and wild mango cv. Irvingia gabonensis and wombo-
lu (Ehiem and Simonyan, 2012). However, information involving the determination of
physical properties of date palm fruits cv. Khadrawy and Medjool has not been reported.
Therefore, the objective was framed accordingly to investigate some physical properties
of date palm fruits cv. Khadrawy and Medjool. The properties, viz., pulp moisture con-
tent, seed moisture content, fruit linear dimensions (length, width, thickness), arithmetic
mean diameter, geometric mean diameter, sphericity, colour values (L, a, b), bulk density,
true density, porosity and coefcient of static friction were determined.
MATERIAL AND METHODS
Fruits of date palm cv. Khadrawy were procured from Regional Research
Station, PAU Ludhiana, Abohar, and fruits of cv. Medjool were procured from the
farm orchard of ICAR-CIPHET, Abohar (Fig 1). The fruits were cleaned before
using for further experimentation.
Fig. 1. Pictorial view of date fruits (Khadrawy and Medjool) – date fruit: (a) cv. Khadrawy; (b) cv. Medjool
DETERMINATION OF SOME PHYSICAL PROPERTIES ... 219
Average size of the randomly selected fruits was determined by measuring three
linear dimensions specied as length (L), width (W) and thickness (T) by digital
vernier callipers (Mitutoyo Corporation, Japan) (least count 0.01mm). Some other
associated parameters like geometric mean diameter (Dp), arithmetic mean diam-
eter (Da) and sphericity (Φs) of the seeds were also calculated using the relationship
given by (Mohsenin 1970).
Dp=(L×W×T)1/
3
(1)
Da=L+W+T
3(2)
Φs=(LW T )1/3
L(3)
Surface area (S) was found by analogy with a sphere of the same geometric
mean diameter, using the following relationship as reported by Altuntases et al.
(2005). It is calculated and represented in mm2.
S=πD2
p
(4)
Bulk density was measured using a wooden box with inside dimensions of
100×100×100 mm. Fruits were poured into the box of known volume, removing
excess fruits by rolling a measuring scale on the rim of the box without compaction.
The weight of the poured box was taken and the procedure was repeated ten times
and average bulk density was calculated by dividing the weight of the poured box
by the volume of the box (Dutta et al. 1988). True density was determined using
the toluene displacement method in which the volume of toluene displaced was
estimated by immersing the weighed quantity of fruits in toluene. Porosity (ε) was
calculated using the relationship given by Vursavus et al. (2006):
ε= 100(1 −ρb/ρt)(5)
where, ε is porosity (%), ρb is bulk density (g cm–3) and ρt is true density (g cm–3).
To evaluate the test weight (100 fruits), 100 fruits were selected randomly and
weighed by means of an electronic balance (Goldtech, India) (least count of 0.01 g).
Coefcient of static friction on four different surfaces, namely plywood, mild steel,
stainless steel and cast iron, was measured by the inclined plane method (Singh
and Goswami, 1996). A single fruit was kept on an adjustable tilting plate and the
M.K. MAHAWAR et al.
220
slope was increased gradually. The angle at which the material just started to move
downward was recorded (α). Coefcient of friction was calculated from the follow-
ing relationship given by Dutta et al. (1988):
µ= tan α(6)
Table 1. Some physical properties of date palm fruits (Khadrawy and Medjool)
Parameters Variety
Khadrawy Medjool
Pulp moisture content (% d. b) 78.12 ± 2.37 69.46±1.21
Seed moisture content (% d. b) 42.47 ± 0.66 39.08±0.31
Length (L) mm 41.75 ± 2.41 48.26 ± 2.49
Width(W) mm 19.46 ± 1.08 29.05 ± 1.75
Thickness (T) mm 19.54 ± 1.09 28.80 ±1.56
AMD 26.92 ±1.19 35.37 ±1.41
GMD 1.09 ± 0.063 2.20 ± 0.062
Sphericity 0.60 ± 0.03 0.71 ± 0.024
100 fruits weight (g) 860.45 ± 4.64 2199.6± 13.30
100 fruit pulp weight (g) 685.40 ± 5.25 1717 ± 8.39
100 fruit seed weight (g) 136.60 ± 7.86 213 ± 6.97
Bulk density (g cc–1) 0.56 ± 0.017 0.59 ± 0.014
True density (g cc–1) 0.93 ± 0.02 0.85 ± 0.015
Porosity 0.40 ± 0.01 0.34 ± 0.007
Pulp: fruit 0.890 0.833
Seed: fruit 0.166 0.111
Seed : pulp 0.199 0.124
L 61.3 ± 4.08 61.56 ± 2.81
a 35.57 ± 5.95 34.79 ± 5.74
b 38.87 ± 6.90 30.22 ± 1.68
Coefcient of static friction (Plywood) 0.19 ± 0.04 0.24 ± 0.055
Coefcient of static friction (GI) 0.17 ± 0.02 0.21 ± 0.038
Coefcient of static friction (MS) 0.15 ± 0.05 0.22 ± 0.030
Coefcient of static friction (SS) 0.13 ± 0.06 0.20 ± 0.037
All values are average with 10 replications, with representation (Average value ± S.D)
RESULTS AND DISCUSSION
The moisture content of both pulp and seed of cv. Khadrawy was found to be
higher than that of cv. Medjool. In the case of Khadrawy variety, moisture content (%
d b) of pulp and seed was 78.12±2.37 and 42.47±0.66, respectively, while for Medjool
variety the values for pulp and seed were 69.46±1.21 and 39.08±0.31, respectively.
Three principal dimensions i.e. length, width and thickness of date palm fruits of both
cv. Khadrawy and cv. Medjool were determined. For Medjool variety, average values of L,
W and T were 48.26±2.49 mm, 29.05±1.75 mm and 28.80±1.56, while for cv. Khadrawy
the values were 41.75±2.41mm, 19.46±1.08 mm and 19.54±1.09 mm, respectively.
Arithmetic and geometric mean diameter was found to be 26.92±1.19 mm and 1.09±0.063
for Khadrawy; 35.37±1.41 mm and 2.20 ± 0.062 for Medjool variety, respectively.
DETERMINATION OF SOME PHYSICAL PROPERTIES ... 221
Sphericity of cv. Khadrawy and Medjool was 0.60±0.03 and 0.71±0.024,
respectively. Fruits of date palm cv. Medjool, being larger in size, attained more
roundness, which resulted in higher values of sphericity. 100 fruits weight was
860.45±4.64 g for cv. Khadrawy and 2199.6±13.30 g for Medjool variety. There
was an increase of around 155% in the 100 fruit weight of Medjool variety as
compared to Khadrawy variety. Hundred fruit pulp mass was 685.40±5.25 g and
1717±8.39 g for cv. Khadrawy and Medjool, respectively. This was due to the pro-
portional increase in the size of Medjool fruit as compared to Khadrawy. Hundred
fruit seed mass was 136.60 ± 7.86 g and 213± 6.97 g for cv. Khadrawy and Medjool,
respectively. This increase of about 56% corresponds to the seed mass of Medjool
variety as compared to Khadrawy variety.
Bulk density of fruits of date palm cv. Medjool (0.59±0.014) g cm–3 was slight-
ly higher than of that of cv. Khadrawy (0.56±0.017) g cm–3. True density of cv.
Khadrawy (0.93±0.002) g cm–3 was higher than of cv. Medjool (0.85±0.015) g m–3.
Porosity of date palm fruits decreased from 0.40±0.01 to 0.34±0.007 with Khadrawy
and Medjool date palm, respectively.
Overall values of the coefcient of static friction were the highest for plywood
surface, followed by galvanised iron, mild steel and stainless steel. This is because
of the resistance of that surface for particle to ow due to the roughness of the sur-
face. Values obtained were on the higher side for Medjool variety as compared to
Khadrawy variety.
CONCLUSIONS
This study dealt with measurement of physical properties of two date palm
varieties (Khadrawy and Medjool), contributing knowledge about the changing
behaviour of the determined properties with inherited varietal differences. The val-
ues for axial dimensions with respect to major and minor intercepts of Medjool
variety were substantially higher as compared to Khadrawy variety. Also, the
weight related parameters, i.e. 100 fruit weight, were observed to be higher for cv.
Medjool. Pulp and seed moisture content was higher for cv. Khadrawy as well, as it
has a higher pulp percentage and pulp: fruit ratio. Coefcient of static friction was
found to follow a decreasing trend with the plywood, galvanised iron, mild steel
and stainless steel surfaces, respectively, for both the varieties. The engineering
properties were observed to be signicantly affected by the varietal differences.
Such information may nd applicability in adequate design and development of
equipments pertaining to post harvest technology and processing of these fruits.
M.K. MAHAWAR et al.
222
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OKREŚLENIE NIEKTÓRYCH WŁAŚCIWOŚCI FIZYCZNYCH OWOCÓW
PALMY DAKTYLOWEJ (ODM. KHADRAWY AND MEDJOOL)
Manoj Kumar Mahawar1, Kirti Jalgaonkar1, Mukesh Kumar2, Vijay Singh Meena1,
Bharat Bhushan1
1Wydział Przetwórstwa Produktów Ogrodniczych, ICAR – Centralny Instytut Inżynierii Pożniwnej
i Technologii, Abohar, Punjab-152116, India
2Szkoła Inżynierii Rolniczej i Technologii, HAU Hisar, Haryana, India
e-mail: manojmahawar362@gmail.com
Streszczenie. Przedstawione badania zostały przeprowadzone w celu oceny niektórych właś-
ciwości zycznych owoców palmy daktylowej odmian Khadrawy and Medjool. Dla obydwu odmian
oceniano wilgotność miąższu, wilgotność nasion, wymiary owoców (wielka i mała oś), średnią
DETERMINATION OF SOME PHYSICAL PROPERTIES ... 223
arytmetyczną średnicę, średnią geometryczną średnicę, kołowość, wartości barwy (L, a, b), gęstość
usypową, gęstość rzeczywistą, porowatość i współczynnik tarcia statycznego. Wartości badanych
właściwości wykazywały znaczące różnice międzyodmianowe, które mogły wynikać z cech charak-
terystycznych obydwu odmian.
Słowa kluczowe: palma daktylowa, właściwości zyczne, Khadrawy, Medjool