Functional Properties of Cowpea Flour and Sensory Qualities of Moin-Moin Produced From Three Varieties of Cowpea Seeds
Chapter One
The Objective of the Study
The objective of this study was to examine the functional properties of cowpea flour and the sensory qualities of Moin-moin from four varieties of cowpea seeds.
CHAPTER TWO
LITERATURE REVIEW
Cowpea (Vigna unguiculata L. Walp)
Cowpea, (Vigna unguiculata L. Walp), belonging to the family Papilonacaeae (Fabaceae or Leguminosae), originated in subSaharan Africa (Brink and Belay, 2006). Cowpea is grown not only in the tropical lowlands, especially in dry areas, but also in warm temperate regions. Cowpea production in Africa is mainly by subsistent farmers. Seed color is diverse and varies from white, cream to red to black to mottled. The seed coat ranges from thick and loose to thick and tightly adhering to thin, wrinkled, and tightly adhering. Cowpea is an important pulse/starchy legume crop in subSaharan Africa, with parts of Asia and the Americas representing other regions of consumption. The total world production of cowpeas in 2019 was 8.9 million metric tons (Food and Agriculture Organization [FAO], 2021), representing 2.7-folds increase since 2000. Nigeria (40.2%), Niger (26.8%), and Burkina Faso (7.3%) contributed 74.3% of total cowpea production. Cowpea is a nutritious food source rich in protein (24%), dietary fiber (11%), and potassium (1112 mg/100 g) while low in lipids (<2%) and sodium (16 mg/100 g) (U.S. Department of Agriculture [USDA], 2021). Cowpea protein has appreciable amounts of essential amino acids except cysteine and methionine.
Composition of Cowpeas
Proteins, Amino acids, and Protein Classification
Cowpea protein is a rich source of essential amino acids except cysteine and methionine, which is typical of other legumes. Although cowpea protein is deficient in sulfur containing amino acids (cysteine and methionine) for infants, it satisfies the requirements suggested for young children and adults (USDA, 2005). The recommended reference intake of methionine + cysteine is 3.8 g/100 g protein for infants, but cowpeas provide only 2.5 g/100 g protein. However, the recommended reference intake of cysteine + methionine for young children and adults is 2.5 g/100 g protein (USDA, 2005). Chan and Phillips (1994) extracted defatted California Blackeye flour with 0.1-M Na3PO4, 0.01-N NaOH, and 70% ethanol. The major protein fractions were globulin (66.6% of total) and albumins (24.9%) whiles alkali-extractable glutelins comprised 4.7% and alcohol-soluble prolamins, 0.7%. As shown by SDS-PAGE, globulins had major bands at 65, 60, 56, and 50 kDa and 28–42 kDa minor bands.
The albumin fraction contained 99, 91, 32, and 30 kDa subfractions; the glutelin fraction, 101, 68, 31, and 29 kDa; and the prolamin fraction, 105, 62, 50, and 54 kDa subunits. All fractions were rich in aspartic and glutamic acids (9.1–11.8%), with comparable amounts of serine, proline, isoleucine, methionine, tyrosine, and histidine. Albumins contained the highest and glutelins the lowest lysine (9.2 and 7.6 g/100 g protein, respectively). Freitas et al. (2004) reported cowpea protein fractions of 51% globulins, 45% albumins, 3% glutelins, and 1% prolamins. Teka et al. (2020) confirmed the predominant protein fractions were globulin (38.4–49.1%) and albumin (19.6–22.5%), followed by glutelins (6.4–10.4%) and prolamins (1.0–1.14%). In vitro protein digestibility of cowpea flour ranged between 68.7% and 72.0% and had significant but negative correlation with phytic acid (r = 0.673) and globulins (r = 0.846) and no correlation with tannins. Except for isoleucine and histidine, the amino acid score of the cowpea was below the FAO/WHO requirement for essential amino acids for infants and preschool children. Tryptophan was the first limiting amino acid, followed by the sulfur-containing amino acids.
Carbohydrates
Cowpeas contain significant content of both digestible and nondigestible carbohydrate. Tuan and Phillips (1991) employed gelatinization, amylase/amylopectinase hydrolysis, and glucose analysis for measuring starch concentration in California Blackeye #5 seeds. Starch content of 48% (control) and 45–54% (stored seeds, at variable temperature and relative humidity) was observed following different pretreatments. Oluwatosin (1998) reported that starch content was 43–64% in 15 Nigerian cultivars grown in three locations. Mallillin et al. (2008) found 34% dietary fiber (TDF) in cowpea, which was comparable with other legumes. Approximately 80% of TDF was reported as insoluble. Raffinose and stachyose content of 0.45 and 3.30 g/100 g, respectively, were reported in cowpea by Nnanna and Phillips (1988). These galacto-oligosaccharides (GOS), also present in other legumes, have negative reputation as flatulence-causing compounds. Various soaking and processing treatments have been suggested to eliminate or significantly reduce their content. However, galactooligosaccharides are now widely recognized as having prebiotic potential, as growth promoters of beneficial intestinal bacteria (Macfarlane et al., 2008).
CHAPTER THREE
MATERIALS AND METHODS
Materials Source
Three varieties of cowpea (Oloyin, Sokoto and Drum beans) were purchased from the main market in Owo with other ingredients such as pepper, maggi, onions, oil and nylon.
Preparation of Samples
Preparation of Cowpea Flour
The cowpea flour was prepared as described in figure 3.1. Cowpea seeds were manually sorted to remove impurities; it was soaked in water at room temperature (35 oC) for 10 mins to soften the testa, which was manually removed and washed off. The cleaned cotyledons were oven dried at 60oC for 24 hours and milled into flour using disc attrition mill, followed by sieving (300- m aperture). All flour samples were kept in high density polythene until needed (Fig. 3.1).
CHAPTER FOUR
RESULTS AND DISCUSSION
Results
Table 4.1: Yield and Functional Properties of Bean Flour produced from three varieties of Cowpea
CHAPTER FIVE
CONCLUTION AND RECOMMENDATIONS
Conclusion
Production of flour from three varieties of “oloyin”, “sokoto” and “drum” serves as means of preservative and utilization of cowpe there by alleviating the post-harvest problem associated with agricultural production. It reduces the preparation and cooking time, reduce lo digestibility and anti-nutritional factor in the product. The production of “moin moin” from cowpea flours will reduce processing time, optimal use of fat which eventually lead to process optimization. The sensory attributes of the moin moin samples revealed that moin moin from oloyin (OBM) was generally accepted in terms of colour, taste, aroma and texture.
Recommendations
On the basis of the work done, I will like to recommend that further work should be carried out on the followings
- Study the storage of cowpea.
- Examine the consumer acceptability of the finished product of “moin moin”.
- Examine the effect of the cereal flour on the finished product.
