Proximate and Mineral Analysis of Some Wild Leafy Vegetables Common in Benue State, Middle Belt-Nigeria

The proximate analysis and mineral composition of some commonly grown and consumed leafy vegetables in the middle belt region of Nigeria were studied to determine their nutritional content. They include Ficus thonningii, Annona senegalensis, Emilia coccinea and Hibiscus sabdariffa. The proximate analyses revealed the following range of result in the fresh sample; Moisture(62.32 -93.38%),Crude Fat( 0.05-0.71%), Crude Fibre (1.30-20.15%), Ash(1.06-2.37%), Crude Protein(0.03-0.33%),Carbohydrate (4.16 -15.12%)and Energy value (17.21 to 67.02 kJ/100g) while that for dried samples were Moisture(11.33-28.58%),Crude Fat(0.57-3.43%), Crude Fibre (10.51-36.86%),Ash(4.70-12.77%), Crude Protein(0.28-1.53%),Carbohydrate (33.11-62.11%) and Energy value(120.57 to 345.7 kJ/100g). There was no significant difference between the nutrient and mineral content of the studied vegetables. The wild vegetables contain appreciable amount of essential nutrient molecules and mineral elements needed for the maintenance of good nutritional status and thus can compete favourably with commonly consumed vegetables.


INTRODUCTION
Nigeria is endowed with numerous varieties of useful plants whose fruits, seeds, stems, roots and leaves serve various important roles in medicine and nutrition Adebowale et al (2013). Unfortunately many of such plants have not been put into maximum use except in times of nutritional stress (McBurney et al, 2004). The neglect of these wild food plants has been attributed to the insufficiency of information on their nutritional profile and potential to serve as food security Afolayan & Jimoh (2009).The United Nation Food and Agriculture Organization (UNFAO) have estimated that the number of undernourished people in developing countries was 824 million in 1990-1992. In 2010, the number had climbed to 925 million people. The target set at the 1996 world Food summit was to halve the number of undernourished people by 2015 from their number in 1990-1992(FAO, 2004. This problem of malnutrition can be reduced by encouraging the use of wild vegetables, as they remain the cheapest source of proteins, minerals and vitamins in the diet of many people (Grivetti and Ogle, 2000; Lyimo et al, 2003). Earlier research on wild mucilaginous vegetable by Ubwa et al (2014) in the same study area had reviewed appreciable amounts of food nutrients in these vegetables and hence their food value is further reiterated.
Ficus thonningii blume is an ever green tree, 6 to 21m tall with a rounded to spreading and dense crown sometimes epiphytic. Its leaves are simply flossy, dark green, thin and papery or slightly leathery, margin smooth, elliptic or obovate, sometimes rather elongated or slightly oblanceolate, grouped at end of twinges (Hines and Karlyneckman, 1993;Gidado and Gwargwor, 2013). Ficus thonnigii is widely distributed in upland forest, open grassland, riverine and rocky areas, it's also found in the savannah Davis (1989). It is an eatable plant that is well consumed among the Tiv speaking people of Benue state, Nigeria. It's also believed to have a medicinal value of curing yellow fever.
Annona Senegalesis is found in tropical rain forest as well as the savannah region of Nigeria and other West African countries. It is sometimes described as a small tree or shrubs since it is about 8feet high Keay et al. (1964). The leaves are sometimes used as vegetable for making soup. The leaves, stem, bark and root of the plant can also be used for medicinal purposes. It has been reported for treatment of ailments such as cancer, cough and for dressing wound (Abdullahi et al. 2003) Emilia coccinea belongs to the family Compositae (Asteraceae). The members of this family are largely woody herbs or shrubs, a few trees and climbing herbs Olorede, (1984). E coccinea is also known as "tassel flower". It is an erect bushy herb of up to 120 cm in height. E. coccinea is an ubiquitous weed of waste place and fallow land. The antimicrobial properties of Emilia coccinea and its use for therapeutic treatment have been investigated by a number of researchers worldwide. According to earlier reports (Odugbemi, 2006). Emilia coccinea has been reported for its medicinal properties for the treatment of syphilis, hernia, gonorrhoea, ulcer, 'craw-craw', abscesses of the breast, ringworm, lice, measles, cough etc. In Nigeria, the leaves are eaten cooked as salad or spinach and the fresh juice of the leaves is a remedy for sore eyes (Sofowora, 1982).
Hibiscus Sabdariffa is a shrub belonging to the family of Malvaceae and is thought to be native to Asia or Tropical Africa Gautam (2004). It is a hardy herbaceous shrub that grows well in most soils that are well drained. The plant is about 3.5 m tall and has a deep penetrating taproot. It has a smooth or nearly smooth, cylindrical, typically dark green to red stems. Leaves are alternate, 7.5-12.5 cm long, green with reddish veins and long or short petioles. Leaves of young seedlings and upper leaves of older plants are simple; lower leaves are deeply 3 to 5 or even 7 lobed and the margins are toothed (Julia, 1987). It is commonly grown in the middle belt and North Eastern regions of Nigeria (Akanya et al. 1997).
The neglect of some of these vegetables coupled with the increased reduction in their consumption prompted this research. The study was aimed at providing the nutritional profile of some of these indigenous vegetables that are found available in Benue state, middle belt region in Nigeria as wild plants.

Sample Collection and Identification
The leaves of the vegetables (F. Thonningii, A. Senegalesis, E. Coccinea, H. Sabdariffa) were collected from the wild around Makurdi, Benue State, Nigeria. The leaves were identified and authenticated by a Taxonomist in the Department of Biological Sciences, Benue State University Makurdi.

Sample Preparation
The collected plant leaves were cleaned and separated into two portions. The first portion was sliced with a knife into smaller pieces and kept in the fridge for fresh sample analysis. The second portion was spread on an already cleaned laboratory bench for two weeks in the Chemistry laboratory of Benue State University, Makurdi. The dried leaves were later pounded into powder with laboratory mortar and pestle. A portion of the powdered sample was then kept for determination of the various parameters.

Experimental Analysis
The proximate analysis (Protein, fats, fibre, ash, moisture and carbohydrates) of the fresh and dry samples of the plant leaves were determined by the method described by AOAC (2000) and the ASEAN Manual of Food Analysis (Pwwastein et al. 2011). The total crude protein was determined by Kjeldahl method. The nitrogen value was converted to protein by multiplying a factor of 6. 25.The crude fat content was determined using soxhlet extraction method. The moisture content of the sample was determined by drying the sample to a constant weight at 105 o C in an air-oven. The ash and crude fibre were determined using weight loss method. The carbohydrate content was determined using weight difference method. The energy values of the vegetables were calculated using the conversion factor provided by Food and Agricultural Organization (FAO, 2004b). The mineral content of the fresh and dried samples were determined using PG 990 Atomic Absorption Spectrophotometer.

RESULTS AND DISCUSSION
The results for proximate composition and mineral content of the vegetables studied are presented in Tables 1 and 2 below respectively.  sabdariffa. This is evidenced by the probability value of 0.3892 which is greater than the alpha level of 0.05 (5% level of significance). This similar trend was observed for the mineral content of the dried vegetable samples with p-value of 0.7923 being greater than the alpha level of 0.05 indicative of no significant difference.

CONCLUSION
This study has revealed that the leaves of Ficus Thonningii, Annona Senegalensis, Emilia Coccinea and Hibiscus Sabdariffa contain some appreciable amount of essential nutrient molecules and mineral elements needed for the maintenance of good nutritional status and they compete favourably with commonly consumed vegetables.

COMPETING INTEREST
Authors have declared that no competing interest exist.