PROXIMATE COMPOSITIONS, AMINO ACID PROFILES AND SENSORY EVALUATION OF OKPA COOKED WITH FLUTED PUMPKIN LEAF, SCENT LEAF AND BITTER LEAF

Bambara groundnut (Vigna subterranean) is a legume crop native to Africa commonly grown for its seeds by subsistence farmers. It is grown in many parts of Africa, Asia, Indonesia, and South America (National Research Council, 2006; Basu et al., 2007). Bambara groundnut belongs to the family of fabaceae. It is an annual herbaceous, intermediate plant with creeping stems. The nuts are known as jugo beans (South Africa), ntoyo ciBemba (Republic of Zambia), Gurjiya or Kwaruru (Hausa, Nigeria), Okpa (Ibo, Nigeria), Epa-Roro (Yoruba, Nigeria) and Nyimo beans (Zimbabwe) (Bamishaiye et al., 2011).The colour of the seeds vary from white, cream, red, black and in some cases mottled with colours such as brown, red or black (Amarteifio   et al., 2010).

According to Yao et al. (2005), Bambara groundnut plays a key role in the traditional food and culture of peoples in the western and northern parts of Côte d’Ivoire. Bambara groundnut is now widely distributed in the semi-arid zone of Sub-Saharan Africa (SSA) and most authors seem to support the view that there, it is the third most important food legume after cowpea (Vigna unguiculata) and groundnut (Mkandawire, 2007).

Bambara groundnut is important for small holders and their households because the beans are an important source of food security, and are highly nutritious and also high in protein. Although, it is common with other legumes; Bambara groundnut is deficient in sulphur-containing amino acids (Azam-Ali et al., 2001), some genotypes contain higher amounts of methionine and lysine than is found in other legumes (National Research Council, 2006).

The ripe seed or immature Bambara groundnut (Vigna subterranean) contains about 20% protein, 60% carbohydrates and 7% oil (Goli, 1995; National Research Council, 2006).  Lysine and Leucine are the predominant essential amino acids found in Bambara groundnut (Mune et al., 2011; Mazahib et al., 2013). While the predominant fatty acids found in Bambara groundnut are linoleic, palmitic and linolenic acids (Minka and Bruneteau, 2000). In Nigeria mature fresh bambara groundnut is boiled and consumed as snack while mature dried ones are either roasted and consumed as snack or prepared into Okpa; the matured dried seeds are however, now used in Nigeria to produce milk (Udeze et al., 2014) and like other legume, bambara groundnut is also soaked in water to enhance cleaning and to bring to a safe level its anti-nutritional level before being processed into milk. However, despite its high and balanced protein content, Bambara groundnut remains under-utilised because it takes a long time to cook and contains anti-nutritional factors such as tannins and trypsin inhibitors, and it has poor milling characteristics, as it does not dehull easily. The long cooking time consumes more fuel and water than might be required for cowpea or phaseolus bean. Boiling from fresh may take 45-60 minutes, while dried beans may take as much as 3-4 hours (Barimalaa and Anoghalu, 1997).

Bitter leaf, scent leaf and fluted pumpkin leaf consist primarily of vitamin C, fiber, selenium, folate and polyphenolics (carotenoids and flavonoids). (Egedigwe, 2010). This micro-nutrient helps to build the body immunity against diseases and infections which bitter leaf, scent leaf and fluted pumpkin leaf all contain.

Vernonia amygdalina is commonly called bitter leaf in English because of its bitter taste. Bitter leaf contains bioactive compounds which include: oxalate, phylate, tannins, saponins, flavonoid, cyanogenic glycosides, alkaloids, anthraquinone, steroid and phenol and also nutrients such as vitamin C, fiber, selenium, folate and polyphenolics (carotenoids and flavonoids). (Egedigwe, 2010).

Scent leaf (Ocimum gratissimum), the African variety of basil (Ocimum sp), is widely grown as a perennial herb in tropical Africa, South East Asia, India and Hawaii. It is highly recognized world-wide due to its versatile nutritional, anesthetic, and medicinal uses (Gill, 1992).  Scent leaf is rich in alkaloids, tannins, phytates, flavonoids, oligosaccharides, terpenoids, thymol and saponin, with tolerable cyanogenic content. (Ijeh et al., 2004).  The proximate composition shows a crude protein content of 4.7%, 10.8% crude fibre, and ash content of 12.24% (Mensah et al., 2008).

Fluted pumpkin leaf (Telfairia occidentalis) is a tropical vine grown in West Africa especially southern Nigeria as a leafy vegetable. Common names for the plant include fluted gourd, fluted pumpkin, ugu (in the Igbo language), and ikong-ubong (Efik/Ibibio language). (Akoroda, 1990). Fluted pumpkin leaf contain high levels of potassium and iron (Aiyelaagbe, and Kintomo, 2002).The leaf contain a high amount of antioxidants and hepato-protective and antimicrobial properties. (Nwanna, and Echena, 2008). Due to the nutritional and health benefits of these vegetables, this experiment is designed to prepare Okpa using the three vegetables as well as analyze their proximate composition and amino acids profiles.

Micronutrient deficiency has been considered as a major risk factor for child survival in Nigeria, increasing the risk of death from common diseases such as acute gastroenteritis, pneumonia, and measles (Ekweagwu et al., 2008). The prevalence of micronutrient deficiencies in Nigerian children under 5 years was reported 12 years ago by the Nigerian Food Consumption Survey as, 23.3%, 34.0%, 13.0%, and 20.0% for Vitamin A, iron, Iodine, and zinc, respectively. (International Institute of Tropical Agriculture, 2004). Interventions to prevent malnutrition range from promoting breastfeeding to food supplementation, food fortification, bio-diversification, and dietary diversification, through home gardens and small livestock.

In many part of Eastern-Nigeria, the need for the inclusion of vegetables in the preparation of Okpa has been neglected as commercial sellers only sell Okpa without the addition of different vegetables which adds to the nutrient composition and palatability of the product. Also, due to the poor sanitation of the environment, the food products are exposed if not contaminated with microorganism. The poor preparation of this product has also led to the lack of nutrients as a result of poor cooking practices; the Okpa produced locally is more of quantity than quality. However, the products which are prepared with vegetable maybe of low quality as a result of the loss of nutrient in the vegetable due to the use of high heat in cooking. The need for proper preparation of Okpa cannot be over-emphasized. There is therefore, a need to look into the preparation of Okpa with different vegetables. Due to the problems identified, it is worthy to carry out the project, which is intended to prepare Okpa with vegetables and also analyze the composition and amino acid profiles.

The general objective is to determine the proximate, amino acids profiles and sensory properties of Okpa cooked with three leaves-bitter leaf (Vernonia amygdalina), scent leaf (Ocimum gratissimum), and fluted pumpkin leaf (Telfairia occidentalis). The specific objectives are to:

The result of this work will provide adequate knowledge of the nutritional benefits of Bambara groundnut and the need for the enrichment in the preparation and consumption of Okpa.

This study will assist in the awareness or provision of micronutrient availability in the food product when considered by nutritionist and dietitian as a healthy food that meet the nutritional needs of individuals. It will provide guidelines to dietitians in the preparation and prescribing of therapeutic foods for patients in need of micronutrient present in the Okpa, thereby making Okpa a therapeutic diet.

To producers and sellers, the findings carried out in the work will provide them with knowledge needed for standard preparation of Okpa to meet the health and nutritional needs of consumers. It will make them open for new knowledge and expose them to the need for enrichment.

The consumers of Okpa will find this work helpful as it will guide them in their choice of meal and the need for eating healthy and making right choice based on nutritional standards. It will also meet the nutritional needs for those consumers deficient in some micronutrient of the product.