Nutritional Content of Melochia corchorifolia (Linn.) Leaves
L.G. Hassan ,
S.M. Dangoggo ,
Melochia corchorifolia leaves were analysed for their proximate and mineral composition. On Dry Weight (DW) basis, the leaves had the following proximate composition: crude protein (23.31±2.27%), crude lipid (13.33±2.89%), ash (10.00±0.10%), crude fibre (23.33±2.89%) and available carbohydrate (30.03±2.83%). M. corchorifolia leaves had high moisture content (62.16±6.11% Wet weight) with low energy value (275.66±23.20 kcal/100 g). The mineral composition in mg/100 g DW are: K (7.250±37.50), Ca (750.37±10.58), Mg (108.33±5.77) and P (101.89±0.08), Na (94.00±1.15), Cu (33.50±2.55), Fe (19.91±3.01), Mn (9.68±0.59) and Zn (6.73±0.62). When the minerals detected were compared with US Recommended Dietary Allowances, K, Cu, Fe and Mn were found to be adequate for both adults and children. Furthermore, the leaves have nutrient density >100% except for phosphorus, which is low for pregnant and lactating mothers.
to cite this article:
K.J. Umar, L.G. Hassan , S.M. Dangoggo , M. Inuwa and M.N. Almustapha , 2007. Nutritional Content of Melochia corchorifolia (Linn.) Leaves. International Journal of Biological Chemistry, 1: 250-255.
The useful products obtained from plants directly or indirectly, demonstrate their importance to man. Plants serve as a source of food, medicinal product, energy and shelter to man and his livestock. In the earlier stage man depend on wild food, which is much abundant within his immediate environment. As the population grows, however, sources of food become more difficult for him, which necessitate domestication of many plants. Although more than 250,000 plant species have been described worldwide as sources of food, man depends only on a few species mainly cereals, particularly rice, wheat and corn as the major sources of his food and collectively supply nearly 60% of the worlds food supply (Parvathin and Kumar, 2002; Oliveira et al., 2000). In this contemporary situation focus was on vast wild under-utilised and under-exploited plants, which are the most neglected and untapped natural resource (Vadivel and Janardhanan, 2000) as a source of food to the teaming population particularly to the inhabitants of the developing world where food shortages and famine is mostly experienced.
Green leafy vegetables have been recognised as rich source of micronutrients (minerals and vitamins) and antioxidants (Kala and Prakash, 2004).
Melochia corchorifolia Linn., family Sterculiaceae as described by Akobundu and Agyakwa (1998), is a weed of moist or hydromorphic environment. It is an erect or prostrate bushy perennial herb with a pale brown hollow stem arising from a well-developed root system. The flowers are small, white, pale pink or yellow. The fruits are round, slightly hairy, dehiscent capsules. The seeds are small, dry and dark brown.
Despite the use of this plant as food especially by the inhabitants of the area where this plant grows, no report was available on its nutritional content. The objective of this study is to analyse M. corchorifolia leaves chemically to determine its proximate composition.
MATERIALS AND METHODS
Sample Collection and Sample Treatment
Sample of Melochia corchorifolia used in this study was collected
along the bank of River Zamfara in Jega town, Kebbi State, Nigeria. Prior to
analysis, the plant leaves were destalked and washed with distilled water. The
residual moisture was evaporated at room temperature. The leaves were put in
large paper envelopes and oven dried at 60°C until constant weight was obtained
(Fasakin, 2004). The dried leaves were ground in a porcelain mortar, sieved
through 20-mesh sieve and stored in plastic container. The powdered sample was
used for both proximate and mineral analyses. Fresh leaves were used for moisture
The moisture content of Melochia corchorifolia leaves were determined
by drying ten leaves (in triplicate) in a Gallenkamp oven at 105°C until
constant weight was attained (AOAC, 1990). Ash content was determined by dry
ashing in Lenton muffle furnace at 525°C for 24 h. The nitrogen (N) content
was estimated by micro-Kjeldahl method and crude protein content calculated
utilising 5.3 as the protein: Kjeldahls nitrogen ratio for vegetable analysis
(Asibey-Berko and Tayie, 1999). Crude lipid was quantified by the method described
by AOAC (1990) using the Soxhlet apparatus and n-hexane as a solvent. Crude
fibre was estimated by acid-base digestion with 1.25% H2SO4
(w/v) and 1.25% NaOH (w/v) solutions (AOAC, 1990). Available carbohydrate was
calculated as difference between 100% DM and sum of the percentages of crude
protein, crude lipid, crude fibre and ash (AOAC, 1990). The sample calorific
value was estimated according to the formula:
|Energy (in kcal)
|| (2.44xg protein) + (8.37xg lipid) + (3.57xg available
carbohydrate) (Asibey-Berko and Tayie, 1999).
One gram of the powdered sample was digested with 25.0 cm3 concentrated HNO3 using Tecator digestion block until evolution of brown fume stopped. One centimeter cube of perchloric acid was added to the mixture and the content was further heated to a clear solution. After heating, 30 cm3 of hot distilled water was added to the digest and heated to boiling. The solution was then filtered hot into a clean 50 cm3 volumetric flask, cooled and made up to the mark with distilled water (Tayie and Asibey-Berko, 2001). Two more duplicate digest solutions and a blank were prepared.
K and Na were analysed by flame spectrometry (with Corning 400 spectrophotometer)
KCl and NaCl were used to prepare the standards. Phosphorus was determined colorimetrically
with Jenway 6100 spectrophotometer using phosphovanado-molybdate method with
KH2PO4 as the standard. Calcium and Magnesium were analysed
by titrating the samples solutions against EDTA solution using Calcon and Erochrome
Black T indicators (AOAC, 1990). The concentrations of Cu, Fe, Mn and Zn were
determined with a Unicam 969 model atomic absorption spectrophotometer with
standard air-acetylene flame.
To evaluate the nutritional significance of mineral elements, Nutrient Density
(ND) of the sampleswas computed using the equation:
ND (%) = [(Np/Ep)/(Nr/Er)]x100
||Nutrient concentration (mineral element in the food).
||Energy supplied by food.
||Recommended daily intakes of nutrient.
||Recommended energy intake (3000 kcal day-1 for an adult male
given by WHO/FAO (Cole, 1980).
RESULTS AND DISCUSSION
The proximate analysis of Melochia corchorifolia leaves is presented in Table 1. As with most fresh leafy vegetables, the leaves have high moisture content. The leaves also had high percentage of crude lipid when compared to most values (0.33-4.57%) obtained in some edible green leafy vegetables (Guil-Guerrero et al., 1998; Ishida et al., 2000; Agbo, 2004; Gupta et al., 2005). However, high crude lipid was also reported in some tropical vegetables (8.3-27.0% DW) (Ifon and Bassir, 1980; Sena et al., 1998).
The ash content was high in the leaves, but within the range of 9.2±1.5 to 28.0±1.1% reported in green leafy vegetables of Nigeria (Ifon and Bassir, 1980; Ladan et al., 1996).
M. corchorifolia leaves contain high amount of crude protein (23.31±2.27% DW) which is within the range of 17.2±0.1 to 27.03% DW reported for some Nigerian leafy vegetables (Ifon and Basir, 1980). This suggest that this leafy vegetable could be utilised as cheap source of protein supplement. When compared to the recommended dietary allowances for adult (34-56 g day-1) and children (13-19 g day-1), it further indicates the potential of this plant as a protein source.
Dietary fibre is an important component of food in human nutrition as it promotes gut motility and reduces serum cholesterol level, breast cancer and hypertension (Anhwange et al., 2004; Hassan and Umar, 2004). This ability is due to reduction in the rate of absorption of glucose and fat by fibre (Ekop et al., 2004). In this analysis, M. corchorifolia leaves were found to have high fibre content (23.33±2.89% DW). This value is comparable to the fibre content of Gynandropsis gynandra leaves (Hassan et al., 2005).
The estimated available carbohydrate is low compared to the RDA value (130 g) for adults and children (Hassan and Umar, 2006). According to Ifon and Bassir (1980), leafy vegetables may not be important sources of carbohydrate as they are eaten along with other carbohydrate rich food such as cereals. Main function of carbohydrate in the body is for energy supply. The plant leaves energy value 275.66±23.20 kcal/100 g DW (1153.30 J/100 g DW) was within the range of 84-2500 kJ/100 g reported for plant foods (Saka and Msonthi, 1994). This value is low compared to adult energy requirement (3000 kcal day-1) (Cole, 1980).
Table 2 shows the mineral profile of M. corchorifolia leaves. Potassium is the most abundant (7.250±37.50 mg/100g DW), followed by calcium, magnesium and then phosphorous with values in mg/100g DW of 750.37±0.58, 108.33±5.77 and 101.89±0.08, respectively. With the exception of potassium, all the above mentioned elements in M. corchorifolia leaves are lower compared to those reported in Gynandropsis gynandra leaves (Hassan et al., 2005) and some tropical leafy vegetables (Aletor and Adeogun, 1995). Sodium content is the lowest among the macro elements determined. This observation agrees with many other reported results, that have shown sodium to be present in low concentration particularly when compared to potassium.
Microelements play a vital role in human nutrition, as they are dietary essential.
However, high concentration above the safe level is toxic to the body. Iron
is the second most abundant found among the trace element analysed. When compared
with other green leafy vegetables, M. corchorifolia leaves have lower
value than 110-325 mg/100 g DW found in some Nigerian leafy vegetables (Ifon
and Bassir, 1979; Ladan et al., 1996), but within the range of 4.3-119.1
mg/100 g found in underutilized leafy vegetables of Republic of Niger (Sena
et al., 1998).
|| Proximate composition of Melochia corchorifolia leaves
|Values are mean±Standard deviation of three determinations
|| Mineral Composition of Melochia corchorifolia Leaves
|*: The data are mean value±standard deviation (SD)
of three replicated, **: Source: Thangadurai et al. (2001)
Iron is an essential trace element for haemoglobin formation, normal functioning
of the central nervous system and in the oxidation of carbohydrates, proteins
and fats (Adeyeye and Otikiti, 1999). Comparing the amount found in this study
with the reference value (Table 2), the level of Fe in the
leaves are adequate to supply the daily iron requirement for adult, children,
pregnant and breast-feeding mothers. Furthermore Copper is the most abundant
microelement found in the plant leaves. High content could be due to intake
of the element by the plant from the soil. The Cu in the leaves is higher than
the reported values (1-2.5 mg/100 g) for some tropical leafy vegetables (Ifon
and Bassir, 1979; Barminas et al., 1998; Sena et al., 1998). Copper
is an essential trace element which exists as an integral part of copper proteins
ceruloplasmin which is a copper-transport protein.
Manganese acts as activator of many enzymes (McDonald et al., 1995) while zinc is involved in normal function of immune system. The Mn content in leaves is within the range reported for some tropical plants (Ifon and Bassir, 1979; Sena et al., 1998) and considered to be adequate if bioavailable when compared with recommended dietary allowances (Table 2). Zinc on the other hand is low compared to recommended dietary allowances.
For all the elements analyses, except phosphorus for pregnant and lactating
mothers, the percentage of Nutrient Densities (ND), were higher than 100% (Table
3). According to Karakaya et al. (1995), food material with ND of
100% supplies the nutrient need in the same proportion, as the caloric needs.
Also if this index is above 100%, then the food provides the nutrients in greater
proportion than the caloric need. On the other hand, values of ND below 100%
indicate that food fails to provide a proportionate amount of the nutrient.
Thus, the result confirm that Melochia corchorifolia leaves are adequate
rich sources of mineral elements, without evaluating the effect of other antinutrient
|| Mineral nutrient density of melochia corchorifolia leaves
From the result it can be seen that Melochia corchorifolia leaves could be used as protein supplement, sources of dietary lipids, fibre and minerals. Furthermore as potassium depresses blood pressure while sodium enhances, based on the results, the plant leaves could be recommended for hypertensive patients.
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