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International Journal of Science and Technology Volume 2 No. 1, January, 2013
IJST © 2012 – IJST Publications UK. All rights reserved.
99
Comparative Vitamins Content of Pulp, Seed and Rind of Fresh and
Dried Watermelon (Citrullus Lanatus)
1Johnson, J. T., 2Lennox, J.A., 3Ujong, U.P., 4Odey, M.O., 5Fila, W.O.5Edem, P.N., 3Dasofunjo, K
1Department of Chemical Sciences, College of Natural Sciences University of
Mkar, Mkar, P.M.B. 017. Benue State Nigeria.
2Department of Microbiology, faculty of Sciences University of Calabar,
P.M.B 1115 Calabar, Cross River State Nigeria.
3Department of medical Biochemistry, Cross River University of Technology, P.M.B.
1123, Calabar, Cross River State.
4 National Research Institute for Chemical Technology P.M.B. 1052 Zaria,Kaduna State Nigeria.
5Department of Biochemistry, College of Medical Sciences University of Calabar,
P.M.B 1115 Calabar, Cross River State Nigeria.
ABSTRACT
The nutritional quality of pulp, seeds and rind of Citrullus lanatus, was evaluated. The study was carried out on both fresh
and dried samples. Results of the investigation reveal that Citrullus lanatus rind was superior to Citrullus lanatus Pulp, seed.
Citrullus lanatus pulp,seed and rind were low in their pro-vitamin A (carotenoid) though that of the rind was higher
compared with other parts of the fruit. More so, vitamin C (ascorbic acid) content of the rind and seed were significantly (p<
0.05) lower compared with the pulp. Beside, the fruits generally were low in B vitamins. Although there was a significant
difference at (p< 0.05) in the nutrient contents in the different parts of the fruits, the nutrients in the seeds and rind which are
the parts always discarded, can contribute immensely to recommended daily allowance and maintenance of good nutritional
status and hence good health for both man and animals.
Keywords: Comparative, Vitamins-Content, Pulp, Seed, Rind Watermelon (Citrullus Lanatus).
1. INTRODUCTION
The optimal diet for everyone as recommended by the
world health and food and agriculture organization is a
low-fat, and fibre diet rich in complex carbohydrate
characterized by a frequent consumption of fruits and
vegetables at least 400g daily as well as whole-grains,
cereals and legumes at least 30g daily (WHO/FAO,2003).
A variety of fruits and vegetables are however consumed
in Nigeria on a daily basis, and they form an integral part
of our diet but most times only the fleshy pulp of these
fruits are consumed leaving the seed and the rind. Fruits
contain a high percentage of water averaging 85%, fats
and protein in very small varying amounts, a fair
proportion of carbohydrate present as cellulose, starch in
small quantity and sugar. Beside their low energy value,
they are known for their high micronutrients
concentrations including carotene or provitamin A,
vitamin k, ascorbic acid, riboflavin, iron, iodine and other
mineral elements (Shiundu, 2004). The main contribution
of fruits in nutrition is vitamins and the main source from
which humans and animals derive their vitamin is from
fruits and vegetables. Vitamin A in fruits is present as the
precursor carotenes (Alpha, Beta and Gamma) which can
be converted to the vitamin in the body. Fruits such as
pawpaw, oil palm, carrots and pumpkins provide large
quantities of carotene. Ngoddy & Ihekeronye (1985)
reported a value of 200 IU each for avocado pear and
passion fruit. Fruits and vegetables provide vitamin and
minerals in quantities high enough to provide the body
with its needs (Fraser & Cooper, 2006). They have been
linked to the management of anaemia because of their
vitamin C content. When consumed with meals, they
enhance iron status of the individual their high content of
vitamin C improves absorption of iron (Wardlaw &
Hamphl, 2007). Seeds and peels of grapes and
pomegranates are also rich sources of natural antioxidant
(Jayaprakash et.al. 2001). Research studies have recently
shown that a diet rich in the vitamin antioxidants (Vitamin
C and E) and the carotenoids is associated with improved
health and a lower risk of coronary heart disease and
cancer (Pamplona-roger,2008). Food of vegetable origin
rich in fibre, minerals and vitamins, also bring substances
to the diet that although,not well understood nor classified
as nutrients, display potent anticarcinogenic and curative
effects on a variety of diseases and illnesses, these
substances are known as phytochemcials (Pamplona-
roger,2008).The fibre content of fruits and vegetables has
been reported to have beneficial effects on blood
International Journal of Science and Technology (IJST) – Volume 2 No. 1, January, 2013
IJST © 2012 – IJST Publications UK. All rights reserved.
100
cholesterol and they aid in the prevention of large bowel
diseases (IFT,1990 & Jenkins,1978). It has also been
reported that populations that consume diet rich in fruits
and vegetables have significantly lower rates of many
types of cancers (Voorrips et.al. 2000). Fruits have high
vitamin, mineral, fibre, phytochemcial and antioxidant in
their pulps, seeds and rinds but they have not been given
much importance in the diets of many Nigerians
especially the seed and rind which most times are
discarded. Due to ignorance of the nutritive value and
their curative advantages, lack of proper storage
facilities, poor distribution, rising cost of fruits, poor
accessibility and affordability (Tindall & Florence,1983),
most low income groups have not given fruit
consumption much impotance in their daily diet. Fruits
botanically are seed containing organs found in the
ripened ovary of a flower. They are the parts of plants that
produce seeds. Fruits mostly are fleshy and juicy some
may be dried such as cereal, grains, nuts and legume pods.
Fruits as reported by Kilgour (1987) form about 4% of the
world’s food supply. Ctrullus lanatus has its origin
according to (Pamplona-roger, 2008) in the hot, dry
regions around the Mediterranean. Its cultivation has
extended to tropical and subtropical regions on the
American continent. The Citrullius lanatus plant is a
herbaceous creeping plant of the botanical family
cucurbitaceous, which produces from 3 to 5 fruits
weighing from 3 to 10 kilogram; the ‘florida giant’ may
weigh up to 20 kilogram (Pamplona-roger, 2008).
Citrullus lanatus fruit is round, oval or oblong, with a
light green to very dark green skin, variously patterned or
stripped and red, yellow or orange flesh. The seeds are
flat and smooth, varying in size and may be white tan,
brown, black red, green or motted (FAO, 1994). The
Citrullus lanatus fruit has a smooth exterior rind (green,
yellow and sometimes white and a juicy, sweet interior
flesh). The rind is used in preserves, jellies and conserves
and to make pickles (Dane et.al. 2004 and Dane & Liu,
2007). Citrullus lanatus can be used for smoothes, sorbets
or granite depending on the texture whether smooth or
coarse. The rind is also edible and is sometimes used as
vegetable (Wada, 1930). In China, they are stir fried,
stewed or more often pickled. The deskinned and de-
fruited rind is cooked with olive oil, garlic, chilipepper,
scallions, sugar and rum. Pickled Citrullus lanatus rind is
also commonly consumed in the Southern United States
(Mandel et.al. 2005).The inner rind which is usually light
green or white contains many hidden nutrients and is
edible, but most times is avoided due to its unappealing
flavor. It contains mainly citrulline which is a known
stimulator of nitric oxide (Science daily, 2008). Citrullus
lanatus juice can be made into wine the seeds are
consumed as snacks in china, Israel and elsewhere. The
pulp is cooked and seeds eaten in Sudan Nigeria and
Egypt (Goda, 2007). Citrullus lanatus contains a
significant amount of citrulline and after consumption of
several kilograms an elevated concentration is measured
in blood plasma (Mendel et.al. 2005). In Africa, seed may
be ground into coarse flour or oil may be extracted from
them, mature fruit may be prepared and used as summer
squash (USDA, 2003). Studies have shown that fruits and
vegetables contain among other vital nutrients, an
appreciable quantity of vitamin, fibre, antioxidants,
phytochemicals and a daily consumption of at least 5 to
10 servings of a wide variety of fruits and vegetable is an
appropriate strategy for significantly reducing the risk of
chronic diseases and to meet nutrient requirement for
optimum health (Liu, 2004). These fruits are consumed,
fresh, canned or processed and its consumption results in
the production of vast amount of agricultural waste from
their seeds and rind. Despite the numerous nutritional
benefits from fruits only a small portion of plant material
is utilized directly for human consumption (El-Adaway
et.al.1999), the remainder part may be converted into
nutrient for either food or feed or into fertilizer. Although
several research work have been done on the nutritional
evaluation of some locally available fruits, Obizoba et.al.
(2004), Akubor & Onimawo (2005), Animawo (2005),
Adepoju & Adeniji (2008), Ene-obong (2001), Itam
(1983), Essien (1994) and Edet (2004), not much has been
done on the nutritional and anti-nutrient contents of many
locally available fruits and their pulp, seeds and rind
which is most times discarded. The knowledge of the
nutritive and the anti-nutrient content of various parts of
these fruits will encourage their consumption in diverse
ways and re-utilization of the vast amount of seeds and
rind discarded as waste for human food, animal feed,
fertilizer and possibly in other value added applications.
2. MATERIALS AND METHODS
2.1 Sources of Materials
8kgs of Citrullus lanatus was bought from the local
markets in Calabar, Obudu and Obubra Local
Government Area in Cross River State. The samples were
bought when available in their fresh state and in sufficient
quantity for the analysis.
3. COLLECTION AND TREATMENT OF
SAMPLES
Four Citrullus lanatus weighing 2kgs each were used for
the vitamins content evaluation.
The fruit were bought at different times for the vitamins
analysis. 4kgs of Citrullus lanatus prepared and dried
using a hot air circulating oven (Gallenkamp hot box size
one) at 50oc and stored in a labeled air tight containers in
a refrigerator. The same quantity was bought and used as
fresh samples for the vitamins evaluation. The samples for
drying were washed and cut open with a knife into small
piece. Citrullus lanatus seeds were removed from the pulp
before separating the red pulp from the rind. The seeds
were washed, allowed to drain and placed on a foil. The
pulp was chopped into shreds, allowed to drain and placed
in another tray lined with foil, the rind was chopped into
International Journal of Science and Technology (IJST) – Volume 2 No. 1, January, 2013
IJST © 2012 – IJST Publications UK. All rights reserved.
101
tiny cubes and placed in a separate tray line with foil,
there were transferred into the oven.
4. DETERMINATION OF VITAMINS
CONTENT
The vitamins in the fresh and dried samples were
determined using the methods of association of vitamin
chemists (A O V C 1966) vitamin A and B were
determined using the spectrophotometer method described
by Kirk and Sawyer, (1991) at 325nm. Vitamin B (Niacin,
thiamin and Riboflavin) was determined using a flame
photometer while viyamin C was estimated by the 24
dinitrophenol hydrazine methods as described in (A O A
C 1966).
5. ANALYSIS OF DATA
The results of the proximate analysis and anti-nutrient
screening were analysed for statistical significance by one
way ANOVA (F- ratio) (Welkowitz, 1976) and student ‘t’
test were applicable values at (p<0.05) were regarded as
significant in comparison with appropriate control. All
data were expressed as means of ± SEM.
6. RESULT
The results of assessment of vitamins content of fresh and
dried Citrullus lanatus presented in (table 1) based on
mg/100g fresh and dried matter.
Statistical evaluation reveals that pro-vitamin A, Niacin
and vitamin C content while those of thiamin and
riboflavin contents of fresh and dried Citrullus lanatus
pulp, seed and rind.
From the table 1, the pro-vitamin A content of fresh
Citrullus lanatus pulp (15.73 ± 0.17) was significantly
lower than of the rind (76.91 ± 0.01) at (P>0.05). The dry
pulp also revealed that the pulp (57.25 ± 0.42) was
significantly lower than the rind (169.58 ± 0.17) at
(P>0.05). The seeds of Citrullus lanatus in both the fresh
and dried samples recorded no value hence, pro-vitamin A
was not present. Statistical, analysis of thiamine content
of fresh Citrullus lanatus as seen in the table reveals that
the seed (0.13 ± 0.00) and rind (0.14±0.00) when
compared with the pulp (0.09 ± 0.00) were significantly
higher than the pulp at (P<0.05). The dry seed (0.11 ±
0.01) and rind (0.13 ± 0.01) were significantly higher than
the pulp (0.06 ± 0.00) at (P<0.05). There was no
significant difference between the rind and seed in both
fresh and dry samples. More so, Riboflavin content of
fresh Citrullus lanatus seed (0.13 ± 0.02) was
significantly higher than the pulp (0.03 ± 0.00) at
(P<0.05). Dry Citrullus lanatus seed (0.11 ± 0.01) was
also significantly higher than the pulp (0.02 ± 0.00) at
(P<0.05). Riboflavin was not detected in the rind of both
fresh and dried Citrullus lanatus.). However, the Niacin
content of fresh Citrullus lanatus rind (0.06 ± 0.01) when
compared with the pulp (0.02 ± 0.00) was significantly
(P<0.05) higher than the pulp but significantly lower than
the seed (3.22 ± 0.00). The seed however was
significantly higher than the pulp. The dry seed (2.97 ±
0.01) of Citrullus lanatus was significantly higher than
the pulp (0.01 ± 0.00) and rind (0.05 ± 0.00) at (P<0.05).
The rind was however significantly higher than the pulp.
Values for the pulp and rind were negligible. Beside,
result shows that the ascorbic acid content of fresh
Citrullus lanatus rind (7.63 ± 0.59) was significantly
(P<0.05) lower than that of the pulp (9.39 ± 0.59) but
higher than the seed (5.35 ± 0.00). Similarly, the dry seed
(2.35 ± 0.59) showed a significantly lower value than the
pulp (4.11 ± 0.59) and rind (2.93 ± 0.59) at (P>0.05) but
the pulp was significantly higher than the rind at
(P<0.05).
7. DISCUSSION
The fresh and dried pulp, seeds and rind of Citrullus
lanatus were analysed and interpreted. The results of
minerals and vitamin content of fresh and dry Citrullus
lanatus seeds was closely comparable to that of Pamplona
(2008) and USDA (2003) who worked on the nutrient
contents of fruits. The values obtained for pro-vitamin A
content in fresh Citrullus lanatus pulp (15.73µg) and
Cucurbita pepo’L pulp(121µg) was lower than the
findings of Pamplona (37.0µg) for Citrullus and (160µg)
for Cucurbita, USDA (366iu). PSro-vitamin A was not
detected in the seeds as observed in the study (0µg). The
flesh of Citrullus lanatus is an important source of
carotenoid, lycopene and beta-carotene (pro-vitamin A) as
reported by Setiawan et.al. (2001) but the pro-vitamin A
content in this study was low in the pulp of Citrullus
lanatus. Except for pro-vitamin A, the B vitamins and
ascorbic acid were lower in the dry sample than the fresh
samples this might be as a result of the volatile
characteristics of these vitamins. The B and C vitamin are
known to be water soluble and heat labile which may be
the reason for their reduction, carotene generally are
unaffected by most processing methods, as reported by
Vieth (1979) the loss of fat soluble vitamin during
cooking is usually lower than their water soluble
counterpart, this could also be the reason for the increased
pro vitamin A content in the dry and more concentrated
sample. According to Anderson (1966) fruits when fresh
provides vitamin C which is essential for strong blood
vessels and healthy gums, but results from this study has
shown that dry fruits also contain an appreciable amount
of vitamins as in fresh fruits, which agrees with Pamplona
(2008) who stated that fresh ripe fruits evidently provides
the greatest level of vitamin, flavonoids and antioxidants
but if not available, it is always better to eat fruits that has
been preserved by some methods than not to eat it at all.
Pro-vitamin A content was significantly high in the rind
of Citrullus lanatus compared with the pulp, the seeds of
Citrullus lanatus were significantly higher than the pulp
and rind in its Niacin content, the B vitamin contents in
International Journal of Science and Technology (IJST) – Volume 2 No. 1, January, 2013
IJST © 2012 – IJST Publications UK. All rights reserved.
102
other part of the fruit was negligible. Ascorbic acid was
significantly high in the pulp and rind of Citrullus lanatus compared with the seed.
TABLE 1. Vitamin contents of fresh and dried watermelon (Citrullus lanatus)
Carotene
(µg/100g)
Thiamine
(mg/100g)
Riboflavin
(mg/100g)
Niacin
(mg/100g)
Ascorbic Acid
(mg/100g)
FWMP
15.73
0.09
0.03
0.02
9.39
±0.17
±0.00
±0.00
±0.00
±0.59
FWMS
0.00
0.13
0.13
3.22
5.28
±0.00
±0.00*
±0.02*
±0.00*
±0.00*
FWMR
76.91
0.14
0.00
0.06
7.63
±0.01*
±0.00*
±0.00
±0.01*,a
±0.59*,a
DWMP
57.25
0.06
0.02
0.01
4.11
±0.42
±0.00
±0.00
±0.00
±0.59
DWMS
0.00
0.11
0.12
2.97
2.35
±0.00
±0.01*
±0.00*
±0.01*
±0.59*
DWMR
169.58
0.13
0.00
0.05
2.93
±0.17*
±0.01*
±0.00
±0.00*,a
±0.59*,a
FWMP = fresh water melon pulp; DWMP = dry water melon pulp;
FWMS = fresh water melon seed; DWMS = dry water melon seed;
FWMR = fresh water melon rind; DWMR = dry water melon rind.
Values are expressed as mean ± SEM, n = 3.
*p<0.05 vs pulp; a = p<0.05 vs seed.
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