Food Science and Technology Project Topics

Comparatives Studies on Two Varieties of Cowpea Flour (Red and White Cowpea)

Comparatives Studies on Two Varieties of Cowpea Flour (Red and White Cowpea)

Comparatives Studies on Two Varieties of Cowpea Flour (Red and White Cowpea)

Chapter One

Objectives of the Study

The objectives of this study are to produce flour from two varieties of cowpea and to examine the effects of drying on the nutrient composition of flour produced from the two varieties of cowpea.


History, Origin and Distribution

Cowpea was domesticated in Africa, presumably in the northeastern part of the continent in present day Ethiopia. The progenitor of the modern cultivated V. u. unguiculata is probably the wild annual form, V. unguiculata var. spontanea. In support of the idea that the crop originated in northeastern Africa, Steele (2006) noted that the variability of the wild relative V. unguiculata spp. Dekindtiana which has also been considered as a possible progenitor of cultivated cowpea is greater in that part of Africa than in West Africa. Pasquet and Baudoin (2001) likewise support a Horn of Africa origin based on ethnobotanical, linguistic, as well as phyto-geographical considerations. Still, some scientists have considered West Africa a possible site of origin because of the high variability of V. u. dekindtiana in this region (Faris, 2005).

Lack of archeological records for cowpea cultivation hinders efforts to establish its site of origin unequivocally. Like its New World relative, common bean, cowpea may prove to have two or more sites of origin. The current consensus seems to be that domesticated cowpea originated in the northeastern region of sub-Saharan Africa (Smartt, 2005) and spread westward and southward from there. This Horn of Africa origin is also supported by recent studies using molecular markers (Ba et al., 2004).

Morphological and Phenological Characteristics

Cowpea is an herbaceous warm-season annual that is similar in appearance to common bean except that leaves are generally darker green, shinier, and less pubescent. Cowpeas also are generally more robust in appearance than common beans with better developed root systems and thicker stems and branches. Plant growth habit can be erect, semi-erect, prostrate (trailing), or climbing depending mostly on genotype, although photoperiod and growing conditions can also affect plant stature. Most cowpea accessions have indeterminate stem and branch apicies. Early flowering cowpea genotypes can produce a crop of dry grain in 60 d, while longer season genotypes may require more than 150 d to mature depending on photoperiod. Flowers are borne on racemes on 15- to 40-mm peduncles that arise from the leaf axils. Two or three pods per peduncle are common, and often four or more pods are carried on a single peduncle if growing conditions are very favorable. The presence of these long peduncles is a distinguishing feature of cowpea, and this characteristic also facilitates hand harvesting (Ba et al., 2004).

Cultivated cowpea seed weighs between 8 and 32 mg and ranges from round to kidney shaped. Pods are cylindrical and may be curved or straight, with between 8 and 15 seeds per pod. The seed coat can be either smooth or wrinkled and of various colors including white, cream, green, buff, red, brown, and black. Seed may also be speckled or patterned. Seeds of well-known cowpea types, such as “blackeye pea” and “pinkeye,” are white with a round irregular-shaped black or red pigmented area encircling the hilum, giving the seed the appearance of an eye.

Emergence is epigeal (similar to common bean and lupin), where the cotyledons emerge from the ground during germination. This type of emergence makes cowpea more susceptible to seedling injury, since the plant does not regenerate buds below the cotyledonary node. The open display of flowers in and above the canopy and the presence of extrafloral nectaries contribute to the attraction of insects. Cowpea primarily is self-pollinating, but out crossing rates as high as 5% have been recorded and care needs to be taken to avoid out crossing during the production of breeder and foundation seed, or unacceptable levels of “off-types” will result (Steele and Mehra, 2000).

Cowpea is a short day plant, and many cowpea accessions exhibit photoperiod sensitivity with respect to floral bud initiation and development, while others are day neutral (Ehlers and Hall, 1996; Craufurd et al., 1997). For some genotypes, the degree of sensitivity to photoperiod (extent of delay in flowering) is modified by temperature (Wein and Summerfield, 2000; Ehlers and Hall, 1996). In West Africa, selection for differing degrees of photosensitivity or differences in juvenility has occurred in different climatic zones such that pod ripening coincides with the end of the rainy season in a given locale, regardless of planting date, which is often variable due to the variable onset of wet seasons (Steele and Mehra, 2000).

This attribute allows pods to escape damage from excessive moisture and pathogens. Photoperiod sensitivity, when appropriately deployed in a breeding program, can be valuable to ensure crop maturity after wet seasons or before drought or cold weather limits crop growth. However, it may constrain the direct usefulness of an otherwise desirable cultivar to a small area of adaptation or even to a specific season within this restricted area.





Two varieties of cowpea (Red and Blackeye beans) were purchased from Oja Oba Market in Ikare, Ondo State. The cowpeas were processed into flour in the processing laboratory of Food Science and Technology. The wares and reagent used in examining the effects of drying on the two varieties of cowpea were obtained from the chemistry laboratory in the Department of Food Science and Technology in Rufus Giwa Polytechnic.




Table 4.1: Proximate composition of two varieties of cowpea





The present study revealed that drying does not have much effect on the nutritional quality of the two varieties of cowpea. The two samples (RCFS and BCFS) still retain their chemical properties, although BCFS has higher nutritional quality after drying compared to RCFS in terms of ash, fat, and protein content while the carbohydrate and fibre content of RCFS is higher than that of BCFS. From the moisture content of both samples, it helps to understand that BCFS will first be subjected to microbial spoilage because of its high moisture content compared to RCFS which will resist the inhibition or growth of microorganism, hence extending the shelf life of food product. In conclusion, drying and processing cowpea into flour can be used in preserving cowpea and the same time retaining the nutritional qualities of the cowpea flour, which effect can be used for future use without losing its nutritional content. At the same time the two varieties of cowpea have little differences in terms of their nutritional content.


Based on the present revealed results on dried cowpea flour, it is therefore recommended that the use of cowpea flour for consumption, fortification with cereal products and uses in food industries should be encouraged, since it’s a cheap dietary nutrients source for the promotion of good health.


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