Food Science and Technology Project Topics

Effect of Soybean Supplementation on the Quality Attributes of Bean Cake (Akara)

Effect of Soybean Supplementation on the Quality Attributes of Bean Cake (Akara)

Effect of Soybean Supplementation on the Quality Attributes of Bean Cake (Akara)

Chapter One

Objective of the Study

The objective of this study was to determine the effect of soybean supplementation on the quality attributes of bean cake (Akara) produced from cowpea.



History, Origin, and Distribution of Cowpea

            Cowpea was domesticated in Africa, presumably in the northeastern part of the continent in presentday 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 phytogeographical 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).

Botanical description of cowpea

The taxonomy of domesticated cowpea (V. unguiculata var. unguiculata) has a history of revisions, changes, and modifications that leave the non-expert perplexed. The pan tropical genus Vigna forms part of the subfamily Papilionoideae under the family Fabaceae (Leguminosae). Cowpea belongs to the subgenus Vigna, section Catiang. It is genetically isolated from other Vigna, which includes only one other distinctly African species, bambara groundnut (V. subterranea). There are several Asian Vigna crop species such as urdbean (V. mungo), mothbean (V. aconitifolia), and mungbean (V. radiata). Morphological, ethnographical, molecular and other criteria led Pasquet (1999) to a classification of V. unguiculata that recognizes 11 subspecies, 10 of which are perennial and one of which (cowpea) is annual. Annual cowpea has two forms, the cultivated V. unguiculata unguiculata var. unguiculata and the wild/weedy form V. u. u. var. spontanea, both of which are inbreeding. V. u. u. spontanea is typically found only near the borders of cultivated cowpea fields and within them.

The 10 perennial V. unguiculata subspecies include (i) some that are exclusively outcrossing: subspecies baoulensis (A. Chev.) Pasquet, ssp. burundiensis Pasquet, ssp. letouzeyi Pasquet, ssp. aduensis Pasquet, and ssp. pawekiae Pasquet, and (ii) others that are both outbreeding as well as inbreeding: ssp. dekindtiana (Harms) Verdc., ssp. stenophylla (E. Mey) Verdc., ssp. tenuis (E. Mey) Marechal, Mascherpa, and Stainier, ssp. alba (G. Don) Pasquet, and ssp. pubescens (R. Wilczek) Pasquet. Pasquet (personal communication to LLM) points out that the number of subspecies is likely to change as additional living material becomes available for study and as new molecular characterization tools are applied. Originally only three, then later four cowpea cultigroups were recognized (Baudoin and Marechal, 2005). A fifth has recently been added (Pasquet, 1998).

Smart (2005) accounted for the emergence of two of the cultigroups on the basis of selection practiced in Asia after cowpea reached that continent, probably via India, about 2000 years ago. The cultigroups are: (1) Unguiculata, the African cowpea treated here, (2) Biflora, an erect woody perennial grown for fodder and seed, (3) Sesquipedalis, grown for its long, succulent pods in the Far East, (4) Textilis, cultivated in northern Nigeria and Niger; it has long peduncles, and is grown for the textile fibers it provides, (5) Melanopthalamus, originally from West Africa, is able to flower quickly under inductive conditions; the seeds have thin and often-wrinkled testa (Pasquet, 1998). The growth habit of cowpea ranges from indeterminate to determinate. As regards plant architecture, there is great variability. Plants range from erect, semi-erect, and prostrate (spreading, creeping) to climbing. One of the key features of cowpea is its long tap root, which enables the plant to obtain moisture at depths that cannot be reached by most plants.

The cowpea genome is estimated to be 613 Mb distributed amongst 22 chromosomes. In this regard, it closely resembles the model leguminous plant, Medicago truncatula (also estimated at 613 Mb) (Arumuganathan and Earle, 2011). The sequencing and analysis of whole genomes of model plants, such as Arabidopsis thaliana, have paved the way for orphan crops like cowpea, where far fewer resources are available for research (Mahalakshmi and Ortiz, 2001). Fortunately, the Kirkhouse Trust, a Scottish Charity established by Sir Ed Southern, has recently committed resources to enable detailed molecular characterization and genetic improvement of cowpea. Thanks to Kirkhouse, the cowpea genome is now being sequenced. The sequencing approach is known as Gene Spacing under the trade name GeneThresherR ( It exploits a fundamental difference between active (transcribed) and inactive DNA, namely that inactive DNA sequences are methylated and active ones are non-methylated. By cloning genomic DNA into a methylation-sensitive bacterial host the sequences that are not methylated are the only recombinant clones recovered. By this means only the active DNA is selected for sequencing.

In a preliminary study conducted by the University of Virginia and Orion Genomics in 2004 using GeneThresherR, Michael Timko and colleagues (Timko, 2006) achieved a fourfold enrichment of the original 600+ Mb of DNA resulting in only 150 Mb of active DNA to be sequenced. Sequencing of the 150 Mb is expected to result in at least 95% of the entire transcribed sequences of cowpea being described. Application of this new technique should accelerate the development of genetically improved cowpea varieties and strengthen the molecular breeding efforts currently underway to introgress desirable traits using markers. Complementary to this are efforts underway by the Generation Challenge Program involving the IITA and collaborators. They are developing expressed sequenced tags (ESTs) for simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs) in cowpea to be used in marker-assisted breeding. The IITA project may pool its efforts with those of the International Livestock Research Institute (ILRI) project on the development of germplasm for livestock nutrition using genomics (Crouch and Ortiz, 2004).

Feltus et al. (2006) recently used the conserved-intron scanning primers (CISPs) approach to study conserved sequences and comparative genomics in orphan crops. Unfortunately cowpea was not one of the crops chosen for study. Cytological studies help us understand the underlying genetic factors that govern interspecific compatibility. Adetula et al.(2005) as well as others have attempted to make wide crosses between domesticated and wild Vigna, especially Vigna vexillata, in the hope of accessing new sources of genes for insect resistance and other needed traits. V. vexillata, like V. unguiculata, has a diploid genome with 22 chromosomes. Adetula and colleagues identified satellite DNA on chromosome 2 and demonstrated this chromosome to be highly variable, thereby lending itself to serve as a marker for breeding. More recently, however, Adetula (2006) found that in 20% of the cells under study, the mitotic chromosome number of V. unguiculata ssp. dekindtiana var. pubescens (TVNu110-3A) was actually 23, confirming a previous study (Adetula, 1999) where the meiotic chromosome number had been determined. Polytene chromosomes occur in highly specialized tissues of some angiosperms and are indicative of high metabolic activity (Carvalheira, 2000).




Collections of Materials

            Cowpea (Vigna unguiculata var. unguiculata) and soybean (Glycine max) were purchased from the main market in Owo, Ondo State. Other materials such as red oil, pepper, maggi, salt etc used in the preparation were also purchased from the same market. The processing were carried out in the processing laboratory and the analysis were carried out in the Chemistry Laboratory of Food Science and Technology, Rufus Giwa Polytechnic, Owo, Ondo State, Nigeria.

Methods of Preparation

Preparation of cowpea and soybean flour

The cowpea and soybean were sorted to remove damage ones and other extraneous materials. Both cowpea seeds and soybean were soaked for 1 hr separately, dehulled and washed. They were all wet milled and dried at 70 oC in hot air oven for 48 hrs and the flours were packaged in side polyethylene bag and store at room temperature for further analysis.




Table 4.1: Proximate Composition of Akara from Cowpea supplemented with Soybean





            The results of proximate analysis of the samples showed that samples produced from cowpea and soybean blends were of better nutritional quality than the control sample, although the organoleptic properties proof that whole cowpea is still better than the mixture. Based on the results of sensory evaluation of akara samples produce with different pastes, it can be concluded that there was no significant difference, in terms of quality and acceptability, between the different samples up to 30% soybean substitution. This is expected to increase the domestic utilization of soybean and possibly an improvement on the nutritional quality of akara.


The consumption of akara produced from cowpea and soybean blends up to 30% is recommended this is due to its nutritional properties of the akara, furthermore further studies should be carried out on how to retain the organoleptic properties of the akara samples.


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