2.2 Cowpea (Vigna unguiculata)
Cowpea is a annual, warm-season legume with wide range of growth habits and native to tropical and subtropical countries. Cowpea plant either can be short and bushy or vine like and it is consist with tap root system. Canopy height, leaf size and shape, flower colour, seed colour and texture can be vary depend on variety. In generally pod is consist with 6-13 seeds and seeds have rough or smooth seed coat and they are kidney shaped. Flowers in branchless inflorescence are stemmed, lobes are fused and upper petals are longer than lateral petals (Walp et al., 2007).
Cowpea is well adapted to dry conditions and therefore mostly grown in Anuradhapura, Hambantota, Badulla, Kurunegala, Batticalo etc. The recommended varieties of cowpea for Sri Lankan condition are MI35, Wijaya, Waruni, Dhawala and Bombay. Among these varieties Waruni variety shows the best performance according to field crop research and development institute. This variety have bluish purple flowers, long pods, reddish brown seeds, determinate growth habit and 1650kgha-1 average yield.
2.2.1 Scientific classification of Cowpea
Kingdom – Plantae
Phylum – Angiosperms
Division – Magnoliophyta
Class – Eudicots
Subclass – Rosids
Order – Fabales
Family – Fabaceae / Leguminosae
Genus – Vigna
Species – Vigna unguiculata (Otun, 2015)
2.2.2 Nutritional composition of Cowpea (Asare et al., 2013)
Component Nutritional value per 100g
Vitamin B3 2.075mg
Vitamin C 1.5mg
2.2.3 Health benefits of Cowpea
Cowpea is consist with 633µg of Vitamin B9, which is also known as folate. For a healthy pregnancy folate is necessary for fetus growth, because deficiency of folate results malformations of limb and heart. Also Vitamin B9 is essential for reducing the risk of neural tube defects (Awika et al., 2011). Therefore cowpea is consist with anti-cancer properties such as inhibition of oxidative DNA damage and induction of detoxifying enzymes (Nderitu et al., 2013). Vitamin A and vitamin C are antioxidants which are found in cowpea and these antioxidants protect the body from cancer and chronic diseases causing free radicals. Cells get damaged from free radicals and this causes abnormal functionality resulting cancers. Regular consumption of cowpea helps to get rid of these free radical damage.
Cowpea is rich in thiamine (Vitamin B1), which is necessary for acetylcholine production. Acetylcholine is a neurotransmitter which connect muscles and nerves. Vitamin B1 helps to prevent heart failures by maintaining healthy function of ventricles. Other components present in cowpea such as, flavonoids and dietary fiber also help to protect from cardiovascular diseases. Flavonoids reduce inflammation and dietary fiber prevent the buildup of plaque in arteries by balancing the cholesterol level in the body.
High soluble fiber content and high magnesium level in cowpea helps to manage diabetic condition. Magnesium is a mineral which is important to regulate blood sugar level, because magnesium helps to convert glucose of the food into energy in our digestive tract. Lack of magnesium can be result with reduced effectiveness in using insulin by cells. Anemia is a disease condition which occur due to lack of red blood cells or hemoglobin in blood because of iron deficiency. Cowpea consumption have better impact on iron supplement to the blood rather than iron injections.
The standard cholesterol level in body is maintained by phytosterols and it is present in cowpea. Also cowpea is a good source of dietary fiber, protein which are important to regulate this cholesterol level. Therefore cowpea is consider as a low glycemic index having food, which is beneficial for maintaining lipid profile in blood. The nutritional composition of cowpea helps for healthy absorption of nutrients. Cowpea promote healthy digestive system as well as good blood circulation. It is resulting with excellent oxygen supplement for vital organs and blood pressure maintenance.