1.1 Background of the study
Among the basic needs of man, food is considered the most important because it sustains life. Bamila (2005), described food as any substance which when taken into the body builds new tissues, repairs or maintains old tissues, provides energy and regulates body processes.
No nation succeeds without enough food to feed her populace all year round. When the foods are available, consumption pattern becomes a problem. Shortage or unavailability of enough food to feed the population of a country is a big political problem. This is because malnutrition affects the intellectual capacity of the country’s citizens.
Malnutrition is a problem that affects all age groups and different sectors of the population in different ways. However, pre-school children, pregnant and lactating mothers are the most vulnerable (FAO, 2002).`
It is an accepted fact that over two (2) billion people worldwide suffer from micronutrient malnutrition. About 100 to 140 million children suffer from Vitamin A deficiency. Some 20 million people are handicapped because of iron deficiency disorder (IDD). Iron deficiency anemia accounts for 20% of maternal deaths in Asia and Africa (FAO, 2002).
Maizya-Dixon, Akinyele, Oguntona, Nokoe, Sanusi, and Harris (2004) observed that micronutrient deficiency in Nigeria is approximately 36.3% of children under the age of 5 years. These children are at different stages of iron deficiency and 29.5% had Vitamin A deficiency.
The food consumption pattern of an individual influences his health and nutritional status. Adequate nutrients intake maintains good health and increases resistance or protects against ill health.
The ability to diversify foods and inclusion of fruits and vegetables in our diets would effectively protect against micronutrient deficiency diseases in Nigeria.
Some micronutrients were singled out because of their obvious health implications. Consumption of adequate diets protects against the adverse of vitamins and minerals deficiencies in Nigeria. Some statistics show that:
- Approximately 40% – 60% of children aged 6 – 24 months are at a risk of death in period immediately before or after birth due to iron deficiency;
- Approximately 100,000 Nigerian infants are at increased risk of death in period immediately before or after birth due to severe anemia in mothers;
- An estimated 11,000 deaths among young Nigerian women every year in pregnancy and child birth because of severe iron deficiency anemia;
- Over 80,000 children each year died from increased susceptibility to infection due to vitamin A deficiency;
- Approximately 25% of Nigerian children grow poorly due to vitamin A deficiency coupled with lowered immunity;
- An estimated 350,000 Nigerian babies are born each year with intellectual impairment due to iodine deficiency in pregnancy and others(FAO/WHO, 1996)
These nutrient deficiencies were a function of poor nutrition education and failure to grow foods in home gardens to adequately address these nutritional problems in Nigeria. Some foods are rarely consumed in Nigerian homes. However, the cause of inadequate consumption of these foods is because of ignorance of foods and inadequate preparation, etc. Many of these foods are available due to their high yield. Aerial yam or adu in lgbo language, ewuraesi in Yoruba and doyarbisa in Hausa languages and cowpea which is agwa in lgbo, ewa in Yoruba and wanke in Hausa languages are among these food crops. Combination of these food crops and their consumption may provide adequate nutrients to maintain good health. Seasonality precipitates micronutrient and general nutrient deficiencies.
1.2 Statement of problem
Nigeria as a nation has many food crops, which if carefully processed would add to the nutritional status of her citizens. Some of these food crops have limited consumption in Nigerian homes. This is because of inadequate processing and methods of preparation for consumption. Aerial yam (Dioscorea bulbifera) and cowpea (Vigna unguiculata) are among the high yielding crops in Nigeria. Nigeria literature on the food potentials of combinations of aerial yam and cowpea are scarce. Not much study had been undertaken on aerial yam as a food crop despite its high yield. One would regard this food crop as a lesser-known tuber, especially in Nigeria. Cowpea is a crop that yields much, locally produced and once dried it is available all the year round. Aerial yam also has high yield and could keep long all the year round. Both aerial yam and cowpea can contribute to food security. There are no studies on nutrient content of blend of aerial yam and cowpea subjected to various food processing techniques in Nigeria literature.
The thrust of this study is to germinate and ferment these two crops, produce their flours and determine the nutrient content of these flours as well as evaluate the biological value of their blends in adult albino rats.
1.3 Objective of the study
The general objective of the study was to determine the chemical composition and nutritive value of blends of processed aerial yam (Discorea bulbefra) and cowpea (Vigna unguiculata).
Specific objectives were
- Subject aerial yam (Dioscorea bulbifera) and cowpea (Vigna unguiculata) to food processing techniques of germination and fermentation to produce flours;
- determine the nutrient composition of the flours, especially micro-nutrients (iron, zinc, calsuim and phosphorus);
- determine the anti-nutrients and food toxicants (tannins, phytate, oxalate saponins and haemaglutinin);
- determine the functional properties of the flours (fat absorption capacity, water absorption capacity, nitrogen solubility and foam capacity)
- evaluate the nutritive value (mineral and nitrogen) of the blends of germinated and fermented aerial yam and cowpea flours as sole sources of protein in diets fed adult albino rats.