ABSTRACT
Cassava (Manihot esculenta Crantz) varieties: TME 4779, TME 419, NR 8082, TMS 30572 and TMS 93604 gotten from Enugu state, were processed into flour. Comparative studies of their physicochemical and organoleptic properties were evaluated. Anti-nutrient (HCN) composition was determined on the cassava roots, functional properties were carried out on the cassava flour, proximate, mineral and sensory attributes of the cassava flour and bread were also analyzed. Atomic spectroscopy, extraction, kjeldahl methods were used to determine the mineral and proximate properties of cassava flours and bread respectively. Functional properties were determined by physical, chemical and organoleptic assessment of the flour samples while sensory analysis of the cassava flour varieties and cassava-wheat bread was carried out by semi-trained panelists using the 9-point hedonic scale. Results obtained showed that the moisture, crude fiber, ash content and carbohydrate content of the five cassava-wheat bread differ significantly (p≤0.05) as they ranged from 26.00-31.05, 1.48-1.69, 2.37-2.67, 44.01-50.55 respectively while for crude protein, the values were not significantly different (p≥0.05) as they ranged from 12.66-13.99. Also, the swelling index, oil absorption capacity, emulsification capacity and water absorption capacity of each sample was significantly (p≤0.05) different. The combination levels for bread containing wheat and cassava varieties of 10% and 20% respectively was found to be acceptable. It was found that the carbohydrate content of cassava-wheat bread of 20% TMS 93604 was higher than the other cassava flour samples. Breads baked with 80% wheat flour and 20% cassava flour were less accepted by the sensory panel in terms of appearance, taste, texture and aroma. Sample 30572A (90: 10) wheat to 10% TMS 30572 cassava flour which had the greatest value for most essential physicochemical properties and hence is a good substitute for 100% wheat flour bread. These results showed that cassava flour has potential to replace part of the wheat flour in the production of bread since there is wide acceptance amongst the judges.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgments v
Table of Contents vi
List of Tables x
List of Figures xi
List of Plates xii
Abstract xiii
CHAPTER 1: INTRODUCTION
1.1 Introduction 1
1.2 Statement of the Problem 3
1.3 Justification of the Study 3
1.4 Objectives of the Study 3
CHAPTER 2: LITERATURE REVIEW
2.1 Bread 5
2.2 Wheat Imports and Impact on Foreign Currency Earning 7
2.3 Composite Flour in Bread making 9
2.4 Determination of the quantity of Composite Flour in Bread making 11
2.5 Cassava 13
2.6 Composition of Cassava Root 15
2.7 Cassava Flour in baked food 16
2.8 Nutritional Value of Cassava Roots 18
CHAPTER 3: MATERIALS AND METHODS
3.1 Source of Raw Materials 20
3.2 Sample Preparation 20
3.2.1 Production of Cassava Flour 20
3.3 Formulation of Composite Flour 22
3.4 Production of Bread 23
3.5 Determination of Functional Properties of Flour 25
3.5.1 Bulk Density 25
3.5.2 Water Absorption Capacity 25
3.5.3 Oil Absorption Capacity (OAC) 25
3.5.4 Gelation Temperature 26
3.6 Functional Properties of Flour 23
3.5.5 Swelling Index 26
3.5.6 Determination of Emulsion Activity and Stability 27
3.6 Proximate Analysis of Cassava Flour and Bread 27
3.6.1 Determination of Moisture Content 27
3.6.2 Determination of Ash Content 28
3.6.3 Determination of Fat Content 28
3.6.4 Determination of Crude Fibre 29
3.6.5 Determination Crude Protein 29
3.6.6 Determination of Carbohydrate Content 30
3.7 Physical Analysis of Bread 30
3.7.1 Determination of Bread Weight 30
3.7.2 Determination of Loaf Volume 30
3.7.3 Determination of Specific Volume 31
3.7.4 Determination of Oven Spring 31
3.8 Mineral Analysis of Cassava Flour and Bread 31
3.8.1 Determination of Magnesium 31
3.8.2 Determination of Phosphorus 32
3.8.3 Determination of Potassium 33
3.8.4 Determination of Sodium 33
3.8.5 Determination of Calcium Propionate 34
3.9 Determination of Hydrogen Cyanide Analysis of the Cassava Root 34
3.10 Sensory Evaluation of Cassava Flour and Bread 35
3.11 Experimental Design 35
3.12 Statistical Analysis 35
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Functional Properties of Cassava Flour 37
4.2 Proximate Composition of the Cassava Flour and Bread 40
4.2.1 Proximate Properties of the Cassava Flour Samples 40
4.2.2 Proximate Properties of Bread Loaves 42
4.3 Physical Properties of Bread Loaves 45
4.4 Mineral Evaluation of Cassava Flour and Bread 48
4.4.1 Mineral Composition of Cassava Flour 48
4.4.2 Mineral Composition of Cassava-Wheat Bread 50
4.5 Anti-Nutritional Factors of Cassava Roots 53
4.6 Sensory Attributes of the Flour and Bread Samples 55
4.6.1 Sensory Evaluation of the Cassava Flour 55
4.6.2 Sensory Evaluation of Cassava-Wheat Bread 58
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 60
5.2 Recommendations 60
REFERENCES 62
LIST OF TABLES
Table 2.1: Proximate Composition of Fresh Cassava Root 16
Table 3.1: Flour Blends Formulation 22
Table 3.2 Recipe for Production of Bread 23
Table 4.1 Functional Properties of Cassava Flour 38
Table 4.2. Proximate properties of the Cassava Flour Samples 41
Table 4.2.1 Proximate Properties of Bread Loaves 43
Table 4.3 Physical Properties of Bread Loaves 47
Table 4.4 Mineral Content of Cassava Flour 49
Table 4.4.1 Mineral composition of Cassava –Wheat Bread 52
Table 4.5 Anti-nutritional Factors of Cassava Root 54
Table 4.6. Sensory Evaluation of Cassava Flour 57
Table 4.6.1. Sensory Evaluation of Cassava- Wheat Flour Bread 59
LIST OF FIGURES
Figure 3.1: Flow chart for Processing Cassava Flour 21
Figure 3.2: Flow chart for Bread Production 24
LIST OF PLATES
Plate 1: Unpeeled Cassava Roots 23
Plate 2: Peeled Cassava Roots 23
Plate 3: Moulded Cassava Dough 23
Plate 4: Cassava Bread Sample 23
CHAPTER 1
1.1 INTRODUCTION
In many developing countries such as Nigeria, bread consumption is expanding and there is an increasing dependence on imported wheat which depletes the country's foreign exchange (Dewettnick et al., 2008). Bread can be described as a fermented confectionary product made mainly from wheat flour, water, yeast and salt by series of process involving mixing, kneading, proofing, shaping and baking. It is an important staple food in both developing and developed countries and constitutes one of the major sources of nutrients such as carbohydrates, protein, fibre, vitamins and minerals in the diet of many people worldwide (Ogunjobi et al., 2010). The consumption of bread in Nigeria is on a steady increase because it is convenient and ready to eat food normally consumed as breakfast and sometimes lunch. It has become the second most widely consumed non - indigenous food after rice (Siddiq et al., 2009).
Milligan et al., (2010) defined composite flour as a mixture of flours, starches and other ingredients intended to replace wheat flour totally or partially in bakery and pastry products. Shittu et al., (2007) also stated that as the composite flours used were either binary or ternary mixtures of flours from some other crops with or without wheat flour. The use of composite flours had a few advantages for developing countries such as Nigeria in terms of: i) the saving of hard currency; ii) promotion of high-yielding, native plant species; iii) a better supply of protein for human nutrition; and iv) better overall use of domestic agriculture production (Bugusu et al., 2001). Composite flour is considered advantageous in developing countries as it reduces the importation of wheat flour and encourages the use of locally grown crops as flour (Hasmadi et al., 2014). Local raw materials substitution for wheat flour is increasing due to the growing market for confectioneries (Noor and Komathi, 2009). Thus, several developing countries have encouraged the initiation of programmes to evaluate the feasibility of alternative locally available flours as a substitute for wheat flour (Abdelghafor et al., 2011). Moreover, the concept of composite technology initiated by the Food and Health Organization (FAO) in 1964 was targeted at reducing the cost of support for temperate countries by encouraging the use of indigenous crops such as cassava, yam, maize and others in partial substitution of wheat flour (Satin, 1988). The FAO reported that the application of composite flour in various food products would be economically advantageous if the imports of wheat could be reduced or even eliminated, and that demand for bread and pastry products could be met by the use of domestically grown products instead of wheat (Jisha et al., 2008). The bakery products produced using composite flour were of good quality, with some characteristics similar to wheat-flour bread, though the texture and the properties of the composite flour bakery products were different from those made from wheat flour, with an increased nutritional value and the appearance. Apart from being a good source of calories and other nutrients, wheat is considered nutritionally poor, as cereal proteins are deficient in essential amino acids such as lysine and threonine (Dhingra and Jood, 2001). Therefore, supplementation of wheat flour with inexpensive staples, such as cereals and pulses, helps improve the nutritional quality of wheat products (Sharma et al., 1999). For example, the protein quality of both the cassava-soya and the cassava-groundnut breads is higher than that of common wheat bread (Nilufer et al., 2008).
1.2 STATEMENT OF THE PROBLEM
Most of the studies conducted on the use of composite flour for bread making purposes (Dhingra et al., 2005; Adeyemi et al., 2007;) were devoted to determining the effect of biological origin of flour and level of wheat flour substitution on their bread making quality while Shittu et al., (2006) were concerned with the effect of baking time and temperature on some physical properties of the cassava-wheat bread loaf but very few detailed studies concerning the nutritional evaluation of bread loaves produced from cassava wheat flour have been performed till now. Hence, the aim of this research was to assess the anti-nutrient, physical, chemical and nutritional properties of the cassava tubers, flour and bread respectively.
1.3 JUSTIFICATION OF THE STUDY
Cassava which has become one of the largest cultivated food products has been found to be a very good source of energy as it contains carbohydrate, dietary fibre, minerals, vitamins and ash. It is also a readily available food product and it is affordable. An inclusion of this essential raw material in bread production will aid in reducing the cost of production of bread and also provide a richer bread product containing essential nutrients.
1.4 OBJECTIVE OF THE STUDY
The main objective of this work was to identify and produce cassava-wheat flour bread using five improved varieties of cassava (TME 4779, TME 419, TMS 30572, NR 8082 and TMS 93604) from Enugu state.
The specific objectives were to;
i. obtain some improved cassava varieties from Enugu state.
ii. produce cassava flour from the roots and evaluate functional composition of the flour.
iii. produce bread from the cassava-wheat flour.
iv. evaluate physical and sensory properties of the bread produced.
v. evaluate proximate, mineral and hydrogen cyanide contents of the root, flour and bread.
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