Abstract:
The results obtained on analysis of the seeds and pods of Sterculia setigera for their nutritional composition revealed that while the seed sample has high crude protein, crude fibre, carbohydrate and fat contents, their contents in the pod sample was very low. The analysis of the mineral profile reveals that the seed of Sterculia setigera is rich in sodium, iron, zinc and manganese. Conversely, the mineral composition of the pod is low.
INTRODUCTION
In developing countries, there is need for a constant search of new food resources to alleviate hunger, which arises from increasing population, shortage of fertile land and nonmechanization of the farming system. Predictions of the future needs based on the current rates of population increase and food production emphasize the seriousness of this problem. Non-timber forest products are important for food security, health, social and economic welfare of rural communities (FAO, 1990).
While every measure is being taken to boost food production by conventional agriculture, a lot of interest is currently being focused on the possibilities of exploiting the vast number of less familiar plant edible resources existing in the wild (Rao, 1994; Felger, 1979; USNAS, 1975). Recently, there have been reports in the literature on the nutritional and industrial potentials of seeds from edible fruits, some of which were hitherto, discarded (Adesomoju, 1987; Idigo, 1989; Ukhun and Uwatse, 1989). Most reports on some lesser-known and unconventional crops indicate that they could be good sources of nutrients and many have the potential of broadening the present narrow food base of the human species (Van Etten et al., 1995; Okigbo, 1977; Aletor and Aladetimi, 1989).
Sterculia setigera is a savanna tree. It is wide spread in the savanna area of tropical Africa; often characteristic of stony hills. It is deciduous, grows up to 12 m high and 15 m in girth. The bark is pale purplish, smooth with thin scales which peel off expose yellowish patches, exuding gummy sap. The 3-lobed leaves, 6-20 cm broad and long, broadly ovate and densely pubescent on both surfaces. Flowers are borne in small inflorescence in the previous year`s shoots. The fruits are composed of 4 or 5 boat-shaped carpels which split to reveal about 12 slate-coloured seeds, 10-15 mm long (Keay, 1989).
This study was carried out to evaluate the nutrient composition of a wild gathered plant fruit (Sterculia setigera) in order to determine the suitability of its use in alleviating deficiencies of micro-nutrients, protein, energy and the prevention of nutritionally associated diseases.
MATERIALS AND METHODS
The study was conducted in 2006. The seed and pod samples of Sterculia setigera were collected from the same plant in Abuja, Nigeria and identified at Seed Research Laboratory Unit, Botany Department, University of Benin. The samples were dried for twenty-one days. The dried seed and the pods were milled to flour in a Wiley Mill to size of 60-mesh with suitable precaution to avoid contamination of the samples. The powders were stored in plastic containers at a room temperature until use. Three replicates were analysed for each of the sample and the standard error of each mean value determined.
Proximate analysis: Moisture content was determined by drying in an oven set at 105°C to dry to a constant weight. The nitrogen content was determined by micro-Kjeldahl method (Humphries, 1956) and crude protein content was calculated by multiplying the Nitrogen (N) value with a constant 6.25. The crude lipid content was estimated by extracting the sample with ether in Soxhlet extractor. The Total Dietary Fibre (TDF) content was determined by using non-enzymatic gravimetric method proposed by Li and Cardozo (1994). Also, the crude carbohydrate content was calculated according to Muller and Tobin (1980). The calorific values of the seed and pod were calculated by multiplying the crude protein, crude lipid and crude carbohydrate content by the factors 16.7, 37.7 and 16.7, respectively (Siddhuraju et al., 1992).
The samples were digested using two types of acid (perchloric and nitric). Jenway Digital flame photometer (mode: PFP 7) was used to measure the level of sodium, calcium and potassium in the seed and pod samples. Finally, cadmium, copper, magnesium, iron, zinc and manganese were estimated using Atomic Absorption Spectrophotometer (model: Buck 200, Buck Scientific, Norwalk).
RESULTS AND DISCUSSION
The crude protein was found to be 21.40% in the seed sample and 4.36% in the pod sample (Table 1). The result, though higher than earlier report on the same species (Ighodalo et al., 1993) is comparable to 22.86, 23 and 29% reported on seeds of Teramnus labialis, shelled rubber and Vigna unguiculata sp. cylindrical (Viswanathan et al., 1999; Ukhun and Uwatse, 1989; Thangadurai, 2005), respectively. The basic role of protein in nutrition is to supply adequate amount of amino acids. Therefore, the seed of Sterculia setigera, has a considerable promise as a protein source.
A considerable quantity of crude fibre (11.58%) was estimated in the seed. This is comparable to a value of 11.90% obtained in Treculia africana (Achinewhu, 1982). A lower value of 3.17% was estimated in the pod. Total carbohydrate content was 21.03% in the seed and 2.11% in pod. This value obtained for seeds are lower than those earlier reported by Ighodalo et al. (1993).
The levels recorded for macro minerals (calcium, potassium, magnesium, sodium and Iron) in the seed sample are 108.0, 105.0, 59.0 and 28.41 mg/100 g DM and 27.12 ppm, respectively. Similarly, 21.0, 11.0 and 17.0 mg/100 g DM, 0.41 and 0.33 ppm were estimated in the pod sample for calcium, potassium, magnesium, sodium and iron (Table 2). For the trace elements (manganese, Zinc and copper), 19.66, 18.74 and 8.69 ppm, respectively were estimated in the seed sample and 0.49, 0.26 and 0.14 ppm estimated for the pod sample. For the heavy metals (lead, chromium, nickel, cadmium and cobalt), only trace quantities were measured in the seed and pod samples. It is interesting to note that the proximate composition, macro and trace element content of the seed is by far higher than that of the pod, but the heavy metal content of the two samples are comparable.
| Table 1: | Proximate composition of Sterculia setigera |
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| DM1 = Dry Matter, Mean?SE | |
| Table 2: | Mineral composition of Sterculia setigera |
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| DM1 = Dry Matter, Mean?SE | |
CONCLUSION
The evaluation of the proximate composition and mineral analysis of Sterculia setigera revealed that the seed sample is by far more nutritional than the pod sample and could be a good source of protein, carbohydrate, macro and trace elements. Consequently, the fruit could be useful in alleviating disease conditions that arises from nutritional deficiencies that is threatening most developing countries including Nigeria.