ABSTRACT
Quality characteristics of cake produced from composite flour of bambara groundnut and wheat was evaluated. Cake was produced from different flour blends (95:5, 90:10 and 85:15) of wheat and bambara nut. Cake processed with 100% wheat flour served as the control. Functional properties of the flours and proximate composition, mineral content, microbial quality and sensory properties of the cake were evaluated using standard laboratory procedures. The data generated were statistically analysed by One Way Analysis of Variance (ANOVA) using Statistical Product of Service Solution (Version 22). The functional properties of the wheat and bambara nut composite flour ranged from 071 to 0.76 g/ml, 2.52 to 3.19 g/ml, 1.62 to 2.15 g/ml, 19.99 to 24.33 %, 46.66 to 54.96 %, 2.49 to 3.54 Sec, 54.50 to 60.00 °C and 1.65 to 1.85 g/ml for bulk density, oil absorption capacity, water absorption capacity, foam capacity, foam stability, wettability, gelatinization temperature and swelling index, respectively. The proximate composition of the cake samples ranged from 22.50 to 29.21 %, 13.10 to 18.11 %, 13.49 to 14.87 % fat, 2.24 to 2.88 %, 0.28 to 0.52 %, 41.14 to 44.50 % and 340.45 to 370.82 Kcal/100g for moisture content, crude protein, fat content, ash, crude fibre, carbohydrate and energy value, respectively. The mineral content of the cake ranged from 58.84 to 62.13 mg/100g, 64.54 to 67.27 mg/100g, 13.49 to 14.87 mg/100g, 241.87 to 249.78 mg/100g, 309.03 to 314.84 mg/100g and 2.44 to 2.73 mg/100g for calcium, magnesium, sodium, phosphorus, potassium and zinc, respectively. The results of microbial analysis showed that the total viable count of the cake samples ranged from 5.00x106 to 10.00x106 CFU/g. No total fungi, lactobacillus and staphylococcus count were detected in the cake samples. The result of sensory evaluation showed that the appearance (5.80 to 8.90), taste (5.50 to 7.85), aroma (5.40 to 7.60), texture (6.00 to 8.50) and general acceptability (5.50 to 8.20) varied with cake made from 100% wheat having the highest mean scores followed by cake supplemented with 5 % bambara nut flour.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of contents vi
List of tables x
List of figures xi
List of plates xii
Abstract xiii
CHAPTER 1: INTRODUCTION
1.1 Background of study 1
1.2 Statement of problem 2
1.3 Justification of study 3
1.4 Objectives of the study 3
CHAPTER 2: LITERATURE REVIEW
2.1 Significance of legumes 4
2.2 Bambara groundnut 5
2.2.1 Nutritional value of bambara groundnut 5
2.2.2 Anti-nutritional factors of bambara groundnut 7
2.2.3 Processing and utilization of bambara groundnut 8
2.3 Significance of cereal grains 10
2.4 Wheat grains 11
2.4.1 Nutritional value of wheat grains 12
2.4.2 Health benefits of wheat grains 14
2.4.3 Processing and utilization of wheat grains 16
2.4.4 Wheat flour 17
2.5 Composite flour 19
2.6 Cake 20
CHAPTER 3: MATERIALS AND METHODS
3.1 Sources of raw materials 22
3.2 Sample preparation 23
3.2.1 Production of bambara nut flour 23
3.2.2 Formulation of composite flour 26
3.2.3 Production of cake 27
3.3 Analytical methods 29
3.4 Functional properties of composite flour 29
3.4.1 Determination of bulk density 29
3.4.2 Determination of wettability 29
3.4.3 Determination of oil absorption capacity 29
3.4.4 Determination of water absorption capacity 30
3.4.5 Determination of gelatinization temperature 30
3.4.6 Determination of foam capacity and stability 30
3.4.7 Determination of swelling capacity 31
3.5 Proximate composition of cake 31
3.5.1 Determination of moisture content 31
3.5.2 Determination of ash content 32
3.5.3 Determination of fat content 32
3.5.4 Determination of crude fibre 33
3.5.5 Determination of crude protein 33
3.5.6 Determination of carbohydrate content 34
3.5.7 Determination of energy value 34
3.6 Mineral content of cake 34
3.6.1 Determination of sodium 34
3.6.2 Determination of calcium and magnesium 35
3.6.3 Determination of phosphorus 36
3.6.4 Determination of potassium 36
3.6.5 Determination of zinc 37
3.7 Microbial analysis of cake 37
3.7.1 Plating 38
3.7.2 Incubation 38
3.7.3 Plate count 38
3.8 Sensory evaluation of cake 38
3.9 Experimental design 39
3.10 Statistical analysis 39
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Pictorial representation of cake samples 40
4.2 Functional properties of wheat and bambara nut flour blends 41
4.3 Proximate composition of cake made from flour blends of
wheat and bambara nut 48
4.4 Mineral content of cake made from flour blends of wheat and bambara nut 54
4.5 Microbial quality of cake made from flour blends of wheat and bambara nut 59
4.6 Sensory properties of cake made from flour blends
of wheat and bambara nut 61
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 66
5.2 Recommendations 66
REFERENCES 68
LIST OF TABLES
Table 3.1: Flour blends formulation (%) 26
Table 3.2: Recipe for production of cakes 27
Table 4.1: Functional properties of wheat and bambara nut flour blends 42
Table 4.2: Proximate composition of cake made from flour blends of wheat and bambara nut 50
Table 4.3: Mineral content of cake made from flour blends of wheat and bambara nut 55
Table 4.4: Microbial quality of cake made from flour blends of wheat and bambara nut (CFU/g) 60
Table 4.5: Sensory properties of cake made from flour blends of wheat and bambara nut 62
LIST OF FIGURES
Figure 4.1: Flow chart for production of the bambara nut flour 24
Figure 4.2: Flow chart for cakes production 28
LIST OF PLATES
Plate 1: Bambara nut seeds 22
Plate 2: Bambara nut flour 25
Plate 3: Wheat flour 25
Plate 4: Cake produced from 100% wheat flour 40
Plate 5: Cake produced from 95% wheat flour and 5% bambara nut flour 40
Plate 6: Cake produced from 90% wheat flour and 10% bambara nut flour 40
Plate 7: Cake produced from 85% wheat flour and 15% bambara nut flour 40
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Cakes are convenient food products (Atef et al., 2011). They are soft bakery products produced by baking a batter containing flour, baking powders and beaten eggs with or without shortenings (Atef et al., 2011). According to the final products desired, other ingredients such as flavourings, nuts, chocolate and dried fruits are also included. Cake, a complete food, rich in fat and proteins is a major snack in the fast food industry and highlight of many celebrations (Kiin-kabari and Banigo, 2015).
Cakes are highly cherished by women and children, and are made from wheat flour because of the unique properties of its protein (gluten) (Onwuka, 2014). Wheat is the most common staple food crop that contributes more calories and proteins to the world diet than any other cereal crops (Abegunde et al., 2019). It contains carotenoids like lutein, β-cryptoxanthin, and zeaxanthin (Xanthophyl: hydroxylated carbons) (Kumar et al., 2011). Wheat also provides substantial amounts of vitamins (notably B vitamins), dietary fiber, and phytochemicals (Shewry and Hey, 2015) which can aid in reducing the risk of coronary heart disease, diabetes, tumor incidence, cancer risk, blood pressure, reducing the rate of cholesterol and fat absorption, delaying gastrointestinal emptying and providing gastrointestinal health (Neelam et al., 2011). Various factors like the increased attention on consumption of functional foods by World nutritional bodies due to different health problems as stated by Kumar and Pal (2015) prompted blending wheat flour with bambara nut flour in cake production.
The concept of using composite flour in production of cakes is not new and has been subject to numerous studies (Oyeyinka et al., 2014; Alozie and Chinma, 2015; Kiin-Kabari and Banigo, 2015). This possess various advantages which includes but not limited to reduction of wheat flour importation, encouragement of the use of locally grown crops as flour (Hasmadi et al., 2014) and saving some foreign exchange which could be used to develop other areas of the economy (Nwanekezi, 2013). However, in selecting the components to be used in composite flour blends, the materials should preferably be readily available, culturally acceptable and provide increased nutritional potential (Ola and Adewole, 2019).
Bambara nut (Vigna subterranea (L) Verdc) remains underutilized compared to peanuts, cowpea and some other legumes (Effa and Uko, 2017). In Nigeria, it is popularly known as ‘Okpa’ by the Ibos, ‘Ekpa-Roro’ by Yoruba tribes and ‘Gurjiya or Kwaruru’ by the Hausas (Bamshaiye et al., 2011; Mabhaudhi et al., 2013). The seeds contain on average 63 % carbohydrates, 19 % proteins and 6.5 % fats; these values are considered sufficient to make this legume a complete food (Bamshaiye et al., 2011). Bambara nut seeds protein score was found to be richer in essential amino acids than groundnut, soya bean and cowpea (Schaafsma, 2012). It is a medicinal crop that has the potential to treat numerous diseases like kwashiorkor (Jideani and Diederickks, 2014). Bambara nut has prospects in improving food security through shelf-stable food products, which could be produced from it (Hardy and Jideani, 2017).
1.3 STATEMENT OF PROBLEM
Wheat, the basic ingredient for cake production is imported into Nigeria involving huge expenditure of foreign exchange leading to high cost of cakes (Bibian et al., 2014). More so, wheat flour, used in the production of cake, is usually characterized by a high carbohydrates and proteins, but this protein has a very low nutritional value, because it contains lower proportion of essential amino acids (Dewettinck et al., 2008). Frequent consumption of such cakes results in stunting, anemia, physical weakness, edema, vascular dysfunction, and impaired immunity (Wu, 2016). Aside this, bambara nut that possess the potential to contribute in combatting the aforestated health issues are grossly underutilized (Ola and Adewole, 2019).
1.3 JUSTIFICATION OF STUDY
Production of cake substituted with bambara nut will go a long way in reducing over reliance in wheat thereby saving the Nation’s foreign exchange, contribute in obtaining adequate protein and amino acids and also in curbing diseases like stunting, anemia, physical weakness, edema, vascular dysfunction, and impaired immunity. This will also contribute in ensuring that Bambara nut is fully utilized in processing of value added products. The cake production process will be of great benefit to cake producing establishments and families that indulge in cake production. Dieticians in developing countries like Nigeria will find this cake valuable in management of protein energy malnutrition.
1.4 OBJECTIVES OF THE STUDY
The main objective of this work was to produce and evaluate cake from flour blends of wheat and bambara nut seed. The specific objectives were to:
i. Process bambara nut into flour
ii. produce composite flour from wheat and bambara nut flours
iii. determine the functional properties of the composite flours
iv. produce cake using the composite flours
v. determine proximate composition and mineral content of the cake
vi. evaluate the microbiological quality and sensory attributes of the cake.
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