International Journal of Chemical and Biomolecular Science
Vol. 1, No. 4, 2015, pp. 222-226
* Corresponding author
E-mail address: email@example.com (L. S. Borquaye)
Nutritional and Mineral Composition of the Fruits
of Solanum torvum from Ghana
Osei Akoto, Lawrence Sheringham Borquaye
, Ama Samba Howard,
Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
The fruits of Solanum torvum are regularly used in many Ghanaian food preparations because of the belief that they are very
nutritious. The main aim of this work was to assess the nutritional and mineral composition of the Solanum torvum fruits.
Proximate analyses of dried powdered fruits were therefore performed. The results indicated that the fruits possess high
moisture content (86.230%). The values for the other parameters checked were carbohydrates 7.033%, proteins 2.322%, fats
0.278%, ash 0.143% and crude fiber 3.993%. Atomic Absorption Spectroscopy (AAS) analysis of essential minerals was
performed to ascertain the concentrations of iron, manganese, calcium, copper and zinc in the fruit. The results were iron
(76.869mg/kg), manganese (19.466mg/kg), calcium (221.583mg/kg), copper (2.642mg/kg) and zinc (21.460mg/kg). Vitamins
A and C contents were also analyzed and found to be 0.078mg/100g and 2.686mg/100g respectively. The high iron content of
the fruits proves the fact that, the fruits truly have hematinic property.
Atomic Absorption Spectrophotometry, Proximate Analysis, Vitamins, Iron Rich Fruits
Received: August 25, 2015 / Accepted: September 2, 2015 / Published online: September 13, 2015
@ 2015 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY-NC license.
The Solanum torvum (Solanaceae) plant is a common plant
native to many tropical countries in Africa and the West
Indies. It is also found in some parts of Asia. In Ghana, and
many other countries, the fruits are used for food. The leaves
are used in many traditional medical practises in Africa.
(Adjanohoun et al 1996) The plant grows as a short (about 2-
4 m tall), erect shrub with lots of branches. Solanum torvum
grows into a large thorny impenetrable thicket (Mohan and
Bhandare 2012). Some other species, which belong to the
genus Solanum, are Solanum ficifolium and Solanum
ferrugineum (Langeland and Burks 1998). The fruits of
Solanum torvum are clusters of tiny green spheres (about 1
cm in diameter) that become yellow when fully ripen. They
are thin-fleshed and contain numerous flat, round, brown
seeds (Howard 1989; Liogier 1995; Little, Woodbury, and
Mineral nutrition is a significant aspect of human life and it
plays a pivotal role for healthy growth. These nutritional
minerals have various sources. In many African countries,
wild edible plants are used as food and hence contribute
significantly to the nutritional needs of the people. In Ghana,
Solanum torvum (locally referred to as ‘Kwahunsusua’) is
used essentially for food. In the south of Ghana, especially, it
is added to palm nut soup and some stews. It is a general
belief in the Ghanaian society that the fruit of Solanum
torvum is rich in minerals that help increase the amount of
blood in the human body, hence, it is generally advised by
locals to take the juice of Solanum torvum to prevent anemia.
Various pharmacologically active compounds have been
isolated from Solanum torvum. Aqueous extracts of Solanum
torvum, for example, depress the number of erythrocytes,
leukocytes and platelets in the blood of mice and hence are
International Journal of Chemical and Biomolecular Science Vol. 1, No. 4, 2015, pp. 222-226 223
lethal to them (Tapia, A., R., Astudillo, A., V., & Uribe, R.
1996). Some extracts of the plants have also being reported
to be used in the treatment of coughs, colds and skin diseases
(Sundari, G., S., Rekha, S., and Parvathi 2013). Methanolic
extracts of Solanum torvum fruits have demonstrated a wide
range of antimicrobial activity against certain human and
animal clinical isolates (Chah, Muko, and Oboegbulem
In this work, we report the nutritional content of the fruits of
Solanum torvum. Specifically, we have performed an
extensive proximate analysis and determined the
concentrations of essential metals and vitamins present in the
fruits of Solanum torvum sold in markets of Kumasi, Ghana.
2.1. Sample Preparation
Fresh samples were obtained from the Ayeduase, Ayigya and
Central markets, all in Kumasi. The unripe fruits were
removed from the stalk and well washed with distilled water.
The fruits were then wiped to dry all the water around it.
They were then dried in the oven at 60°C and left overnight.
The dried sample was blended into powder and stored in a
2.2. Proximate Analysis
Total Carbohydrates, Total Ash, Crude Fiber, Crude Fat,
Protein and Moisture Content were determined using
2.2.1. Moisture Content Determination
About 2 g of the fresh sample was transferred to a previously
dried and weighed crucible. The crucible was placed into an
oven and the sample dried for 5 hours at 105°C. The sample
was then cooled in a desiccator and then weighed. The
moisture content is expressed in weight percentage by
measuring the weight loss after drying.
2.2.2. Protein Determination
The Kjhedahl method was used. About 2 g of the sample was
put into a digestion flask and heated with 25 ml of
in the presence of selenium catalyst. The
sample was digested using a digestion burner till a clear
solution was obtained. The digested sample was then
transferred into a 100 ml volumetric flask and topped to the
mark. 25 ml boric acid was measured into a 250 ml conical
flask and two drops of mixed indicator was added. The
apparatus was flushed with boiling distilled water and then
the liquid was drained from the steam trap before use. The
conical flask and its contents were then placed under pressure
in such a way that the tip was completely immersed in the
solution. 10 ml of the digested sample solution was poured
into the steam jacket through a funnel and then 15 ml of 40%
NaOH was then added to the decomposition flask. The funnel
stopcock was closed to drive the liberated ammonia into the
collection flask. Steam was forced through the decomposition
chamber by shutting the stopcock on the steam trap outlet.
The boric acid changed to bluish green as soon as it came
into contact with the ammonia. The conical flask was then
removed after 5 minutes. The content of the flask was titrated
against 0.1 N HCl until the solution became colorless. This
was done in triplicate. A blank titration was done to correct
for traces of nitrogen in the reagents.
2.2.3. Crude Fat Determination
About 2 g of the sample was transferred into a Whatman
paper and sealed. 150 ml of petroleum ether was poured into
previously dried and weighed round bottom flask. The
sample was then placed into the Soxhlet extractor and the
condenser connected to it. The setup was assembled and the
flask placed onto the heating mantle. The sample was then
refluxed for 4 hours. After the extraction, the thimble was
removed and the solvent recovered. The fat that was obtained
was then dried together with the flask in an oven for 30
minutes at 105°C. It was then cooled in a desiccator and
2.2.4. Crude Fiber Determination
The sample in the filter paper used for the fat determination
was transferred into a 750 ml Erlenmeyer flask and 0.5 g of
asbestos was added. 200 ml of boiling 1.25% H
added immediately and the flask was set on a hot plate and
the condenser was connected. After 30 minutes the flask was
removed and its contents were immediately filtered through a
clean linen cloth. The sample was then washed repeatedly
with a large volume of water until the washings were no
longer acidic. 200 ml of 1.25% of boiling NaOH was added
to the filtrate. It was also boiled for 30 minutes and washed
several times until it was no longer basic. The residue was
then transferred into a weighed crucible. The crucible and its
content were dried and ashed for 30 minutes. The crucible
was then cooled and weighed. The percentage crude fiber
was expressed as weight loss in percentage.
2.2.5. Total Ash Determination
About 2 g of the sample was measured into a previously
weighed crucible. The crucible together with the sample was
put in a furnace (600°C) for 2 hours. The crucible was then
removed and cooled. The total ash was expressed as a
percentage of the initial weight.
2.2.6. Total Carbohydrate Determination
The total carbohydrate content of the sample was obtained by
224 Osei Akoto: Nutritional and Mineral Composition of the Fruits of Solanum torvum from Ghana
taking the difference between 100 and the sum of the
moisture, crude fiber, protein, fat and ash contents in the
2.3. Essential Metals Determination
2.006g of ash from the total ash determination was used for
the essential metals determination. The ash was dissolved in
5% HCL in the crucible used for the ashing. The solution was
transferred into a 50 ml volumetric flask and topped to the
mark. The essential metal content was analyzed with an
Atomic Absorption Spectrometer (AAS).
2.4. Determination of Vitamin A
The unripe fruits were well washed with tap water and
blended with a little amount of water. This was then sieved
and transferred into a clean bottle to be stored. About 10 ml
of the sample was measured and poured into a mortar. A
spatula full of anhydrous sodium sulphate was added to
remove the water in the sample. 45 ml of acetone was added
in bits to the sample while grinding. The mixture was
filtered. The filtrate was transferred into a separating funnel
containing 20 ml of petroleum spirit and then washed with
water by using a wash bottle to wash the sides of the funnel.
This was repeated until the aqueous layer was no longer
turbid. The organic layer was filtered by placing a few grams
of anhydrous sodium sulphate on the filter paper. 2 ml of the
organic layer was measured into a small test tube. Nitrogen
gas was used to evaporate the sample to dryness and then it
was reconstituted with 700 µl of methanol dichloromethane
(50:50). 20 µl of the sample was then injected into a
Shimadzu HPLC with an ODS C18 column and a mobile
phase of acetonitrile, dichloromethane and methanol
(70:20:10) in isocratic mode. Analyte was monitored at 452
nm (Ahamad and Saleemullah 2007).
2.5. Determination of Vitamin C
A juice of the sample was made by using about 50 g of the
fruits and 200 ml of water by blending and sieving. 5 ml of
metaphosphoric acid/acetic acid and 2 ml of the juice were
measured into an Erlenmeyer flask and the solution was
titrated against indophenol dye.
Fig. 1. Nutrient Composition of Solanum torvum fruits.
3. Results and Discussion
The fruits of Solanum torvum possess a very high moisture
content (86.230%) as depicted in Fig 1. For the other
parameters, the results obtained indicated that carbohydrates
7.033%, proteins 2.322%, fats 0.278%, ash 0.143% and
crude fiber 3.993%. Analysis for essential metal contents (Fig
2) also gave the following results; iron 76.869mg/kg,
manganese 19.466 mg/kg, calcium 221.583 mg/kg, copper
2.642mg/kg and zinc 21.460mg/kg. In the determinations of
the vitamins, 0.078mg/100g and 2.686 mg/100g were
obtained for vitamins A and C respectively.
In a similar study conducted in India, proximate composition
analysis revealed a lower moisture percentage (80.5 %) but a
much higher ash content (12.3 %). Iron, copper and
manganese were found to be below 0.5 µg/mL (which is
equivalent to mg/kg or ppm). Calcium was the most abundant
mineral as well in that study (Bhagyashree et al. 2012).
International Journal of Chemical and Biomolecular Science Vol. 1, No. 4, 2015, pp. 222-226 225
Fig. 2. Essential metal composition of Solanum torvum fruit.
In many parts of Ghana, traditional healers usually prescribe
juice made from the fruits of Solanum torvum for the
treatment of anemia and other ailments (Asiedu-Darko 2010;
Koffuor, Amoateng, and Andey 2011). Anemia is usually
prevalent in pregnant women and also in children (WHO
2000). Different types of anemia exist. They include anemia
associated with bone marrow disease, anemia of chronic
disease, aplastic anemia, sickle cell anemia, hemolytic
anemia and iron deficiency anemia (Al-Shawi, A., R., Obaid,
J., A., & Noor, H. 2012). Iron deficiency anemia occurs when
the concentration of elemental iron in the body decreases
significantly. Because iron plays a crucial role in hemoglobin
formation, iron shortage or deficiency results in decreased
healthy red blood cell count (Nagababu, Gulyani, and Earley
2008). A lot of blood is produced by the bodies of pregnant
women to support the development of both mother and child.
Anemia is therefore a severe complication which can have
adverse consequences for both mother and child (Al-Shawi,
A., R., Obaid, J., A., & Noor, H. 2012). The high
concentration of iron in the fruits of Solanum torvum
therefore rationalizes its prescription by herbalists for the
treatment of anemia, especially that which is due to iron
deficiency. This justifies juices made from the fruits of
Solanum torvum as hematinic agents.
Fig. 3. Vitamins content of Solanum torvum fruits.
226 Osei Akoto: Nutritional and Mineral Composition of the Fruits of Solanum torvum from Ghana
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Solanum torvum represent a viable source for these essential
metals and validates it as a good nutritional source.
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consumed food. Extracts of the fruit possess high iron
content and therefore justifying their use as haematics.
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