1.1 PROJECT BACKGROUND
Cocoyam (Xanthosoma sagittifolium) belongs to the family Araceae. It is one of the six most important root and tuber crops world-wide (Jennings, 1987; Onwueme and Charles, 1994). The corm, cormel and leaves are important source of carbohydrates for human nutrition, animal feed (Ndoumou et al., 1995; Nyochembeng and Garton, 1998) and of cash income for farmers in Asia, Africa, and Latin America (Onwueme and Charles, 1994). It is grown by farmers with small holdings mainly for its edible tubers and is used as subsistence staple in many parts of Nigeria in particular and generally in the arid sub-tropics in Africa. The average production figure for Nigeria is 5,068,000 metric tonnes which accounts for about 37% of total world output of cocoyam (FAO, 2007).
In Nigeria, cocoyam is one of the important root food crops especially among the low income earners. However, the use of cocoyam is limited to direct consumption through boiling of the tuber, frying in oil or pounding into fufu (a dumpling similar to pounded yam) and eaten with soup and it is also used in thickening soups especially in eastern Nigeria. Cocoyam, despite its uses, is regarded as an underutilized tuber, and an insufficiently studied crop (Watanabe, 2002). This is partly because it suffers very stiff competition from yam and cassava, which is preferred for consumption. The palatability problems of cocoyam: bitter and astringent taste and scratchiness in the mouth and throat, as reported by Sefa-Dedeh and Agyir-Sackey (2004) and Iwuoha and Kalu (1995), has also contributed to its being less accepted and thus categorized as an underutilized tuber crop.
In the Eastern part of Nigeria, it serves as staple food and is used as a thickener in food preparations. This is because the starch grain of cocoyam is small and has improved digestibility as this is an important factor when selecting a starchy food that will not be cumbersome on the digestive system (Ihekoronye and Ngoddy, 1985). Cocoyam is rich in digestive starch,
good quality protein, vitamin C, thiamine, riboflavin, niacin and high scores of protein and essential amino acids (Onayemi and Nwigwe, 1987; Lewu et al., 2009). Cocoyam like other root crops deteriorate few weeks after harvest due to inadequate post harvest technologies and this makes the crop scarce and expensive outside the harvesting period. Processing of cocoyam into flour will automatically extend the shelf life of the commodity thereby making it available for use all year round. Processing of food commodities into flour involves drying of the food commodity in order to reduce the moisture content to a minimal level where the food material will be shelf stable.
Bambara groundnut is an important but under-utilized legume which is potentially very rich in proteins and minerals (Minkaet al., 1999). It is widely cultivated throughout tropical Africa, India, Sri-Lanka, Indonesia and Malaysia (Duke, 1981). Of the total annual production of
around 300,000 tons, approximately half is produced in West-Africa (Doku and Karakari, 1971). Its centre of origin is believed to be Bambara, near Timbuktu in Central Mali, West Africa (hence the name Bambara groundnut). It is now widely distributed and grown in Asia, Australia, Central and South America. Known varieties are White, Cream (Plain or spotted), Brown and Black. Bambara groundnut is a type of legume of family Fabacea. This leguminous crop (Vignasubterranea) is an indigenous, underutilized secondary food crop in semi-arid Africa
(Adjetey and Sey, 1998), and is widely produced in Nigeria, especially in Borno, Taraba,
Anambra, Sokoto, Bauchi, Benue, Yobe, Adamawa and Gombe states (Atiku, 2000). They can
be eaten fresh or boiled after drying and have potential use in Agriculture as cover crops, green
manure and mulch as they improve soil fertility by fixing Nitrogen.
Bambara groundnut (V. subterranea) has been found to contain carbohydrates (54.5%-69.3%), proteins (17%-24.6%), fat (5.3%-7.8%), calories (367- 414kCal per 100g). It is a good source of fibre, calcium, iron and potassium. It is unusually high in methionine, an essential Sulphur containing amino acid. The beans have a potential for acting as a substitute and providing a balanced diet in areas where animal protein is expensive and cultivation of other legumes is risky because moisture levels are unfavorable.
1.2 STATEMENT OF PROBLEMS
Nigeria is faced with the problem of malnutrition due to deficiency of protein and calories. The protein-calories sources of vegetable origin have been proposed as a solution to this problem. In Nigeria and many African countries, Cocoyam (Xanthosoma sagittifolium) are used as an inexpensive source of calories.
In recent years, research efforts in the developing countries have focused on the improvement of protein quality of cereals and tuber crops. Various degrees of success has been reported in this area such as fortification of maize with soybean (soy-ogi), cassava with soy flour (cassava -soy flour), fermented yam flour supplemented with soy flour (yam -soy mixture) for “amala”, a popular west African delicacy. Cocoyam cannot meet up with the daily protein requirement, therefore protein supplementation is essential. This initiated the idea of fortifying Cocoyam flour with bambara groundnut in order to curb the global menace of protein-energy Malnutrition.
Cocoyam flour is an upcoming product, gaining the attention of the baking and confectionery industries. On the other hand, Bambara groundnut is an important but under-utilized legume which is potentially very rich in proteins and minerals. It was chosen because of its availability, cheapness as well as high protein composition.
1.4 AIMS AND OBJECTIVE
To investigate the effect of drying on the Proximate and Physico-chemical Properties of Cocoyam flour fortified with Bambara groundnut
- Determination of the proximate and physico-chemical properties of the composite flour.
- To evaluate the sensory attribute of the biscuit made from the cocoyam flour fortified with bambara groundnut.