ABSTRACT
The study evaluated the effects of incorporating flours from a local, and select improved cassava varieties in bread formulation. Tubers of five new, improved cassava varieties, UMUCAS 36, UMUCAS 37 and UMUCAS 38, NR 87184 and TMS 0593 developed by the National Root Crops Research Institute, Umudike were obtained from the research institute and local variety, Nwany oji was obtained from the local farmers, and processed into high quality cassava flour. The flours were used in producing 10 – 20% wheat-cassava bread. The flours were analysed for chemical composition and functional properties. The bread were evaluated for proximate composition and physical and sensory properties. The cassava flours had 8.19 – 11.42% moisture, 0.51 – 1.07% protein, 1.63 – 2.84% crude fibre, 1.10 – 2.63% ash, 0.91 – 1.06% fat and 84.11 – 85.09% carbohydrate. The wheat flour had 9.96% protein, 1.56% lipid 1.04% ash and 0.60% crude fibre. The HCN content of the cassava flours was 2.87 – 6.07 mg/kg. The functional properties of the flours were: bulk density 0.76 – 0.96 g/ml, water absorption capacity 1.12 – 1.46 g/g sample, oil absorption capacity 1.42 – 1.60 g/g sample, foam capacity 12.89 – 16.70%, foam stability 2.04 – 3.03%, emulsion capacity 41.02 – 44.40%, swelling capacity 16.12 – 20.43%, gelatinization temperature 58.82 – 65.02 °C and gelatinization time 1.49 – 2.07 min. The bread had 74.70 – 84.92% dry matter, 15.08 – 25.37% moisture, 6.61 – 12.01% protein, 1.26 – 1.91% crude fibre, 1.02 – 2.87% ash, 1.26 – 2.66% fat and 61.28 – 68.16% carbohydrate. The HCN content of the bread was 0.65 mg/kg – 2.58 mg/kg, increasing as the cassava flour portion increased. The physical properties of the bread were 265.50 g to 375.00 g loaf weight, 693.0 – 1445.0ml loaf volume and 2.61 – 3.76 ml/g for specific volume. Generally, there was in every variety an increase in loaf weight but decrease in loaf and specific volumes with increase in the percentage of cassava flour in the composition. The NR 87184 performed best among the improved cassava varieties. The sensory scores, 6.45 – 8.05 (colour), 5.75 – 7.95 (aroma), 5.90 – 8.05 (taste), 6.55 – 8.05 (crust appearance), 6.65 – 8.05 (crumb appearance) and 5.65 – 7.95 (general acceptability), indicated the samples received a minimum of moderate liking by the consumers. Over all, these cassava varieties looked promising for use in bread formulation. The choice of variety would much depend on intended quality goals. However, it may be the necessary to use appropriate improvers to boost the physical properties of the composite breads. This could encourage the adoption of the wheat-cassava bread policy.
TABLE
OF CONTENTS
Title page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Content vi
List of Tables xi
List of figures xii
List of Plates xiii
Abstract xiv
CHAPTER 1: INTRODUCTION
1.1
Background of the Study 1
1.2
Statement of Problems 5
1.3
Justification 6
1.4
Objective of the Study 6
CHAPTER 2: LITERATURE REVIEW
2.1
Production of Cassava in Nigeria 8
2.2
Chemical Composition and Nutritional Value of Cassava 9
2.3 Processing of Cassava 10
2.4 Importance of
Cassava Roots Processing 12
2.5 Cassava Processing Treatments and Products 14
2.5.1 Cassava processing involving fermentation 14
2.5.2 Processing of cassava into unfermented product
15
2.6
Production of High Quality Cassava Flour (HQCF) 16
2.6.1 Cassava
flour production and quality requirements 16
2.6.2 Starch
composition of cassava flour and HQCF application 17
2.6.3 Functional properties
of starch relative to HQCF use 19
2.6.4 Starch
gelatinization 19
2.7
Cassava Flour in Baked Foods – Application and Challenges 21
2.7.1 The application of cassava flour
in baked food 21
2.7.2 Challenges to the widespread use
of cassava flour in baked food 22
2.8 Wheat flour and its
significance in bread making 24
2.9
Wheat Flour Substitution Policies in Bread Baking in Nigeria 25
2.10 Bread 26
2.10.1 Baking
Procedure 28
2.10.2 Shelf life of
bread 28
2.10.3 Evaluating
physical and sensory quality of bread 29
CHAPTER 3: MATERIALS AND METHODS
3.1
Material Procurement 31
3.2
Flour and Bread Production 31
3.2.1
Cassava flour preparation 31
3.2.2
Composite flour formulation 34
3.2.3
Bread formulation and production 34
3.3
Proximate Composition of Wheat and Cassava Flours and
the Bread Samples 34
3.3.1 Determination of moisture content 41
3.3.2
Determination of ash content 41
3.3.3
Determination of crude fibre 42
3.3.4
Determination of protein content 42
3.3.5 Determination of fat content 43
3.3.6 Determination of
carbohydrate content 43
3.4 Determination of Energy Value 44
3.5 Determination of Hydrogen Cyanide Content 44
3.6 Functional Properties of the Flour 45
3.6.1 Bulk density (BD) 45
3.6.2 Water/Oil Absorption Capacity (WAC/OAC) 46
3.6.3 Foam capacity (FC) and foam stability 46
3.6.4
Emulsification capacity (EC) 47
3.6.5
Swelling capacity 47
3.6.6
Gelatinization temperature and time 48
3.7 Physical Properties of Bread 48
3.7.1 Loaf volume determination 48
3.7.2 Loaf weight determination 49
3.7.3 Specific volume determination 49
3.8
Sensory Evaluation 50
3.9
Experimental Design 50
3.10
Statistical Analysis 50
CHAPTER 4: RESULTS AND DISCUSSION
4.1
Proximate Composition and Cyanide Content of Cassava Flour 51
4.1.1
Dry Matter and Moisture Contents 51
4.1.2
Crude protein 54
4.1.3 Crude fibre 54
4.1.4 Ash 55
4.1.5
Crude fat 56
4.1.6 Carbohydrate 57
4.1.7
Energy 58
4.1.8 Hydrogen cyanide concentration of the cassava flour 59
4.2 Functional Properties of Wheat and Cassava Flour 62
4.2.1 Bulk density 62
4.2.2 Water and oil absorption
capacity 66
4.2.3 Foam capacity and
Stability 70
4.2.4 Emulsion capacity 73
4.2.5 Swelling index
74
4.2.6
Gelatinization temperature and time 75
4.3: Proximate Composition and Cyanide Content of Wheat-cassava
Composite bread 77
4.3.1 Dry Matter 81
4.3.2 Moisture 82
4.3.3 Crude protein 84
4.3.4 Crude fibre 86
4.3.5 Lipid 87
4.3.6 Ash 88
4.3.7 Carbohydrate 89
4.3.8 Energy 90
4.4 Hydrogen Cyanide (HCN) Concentration in the Bread 90
4.5 Physical Properties of Wheat-Cassava Bread Samples
94
4.5.1 Loaf weight 94
4.5.2 Loaf volume 98
4.5.3 Specific volume 101
4.6 Sensory Analysis of Wheat-Cassava Bread 102
4.6.1 Colour 102
4.6.2 Aroma 107
4.6.3
Taste 108
4.6.4
Crust and Crumb properties 108
4.5.5 General acceptability 110
CHAPTER
5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 111
5.2 Recommendations 113
References 114
LIST OF TABLES
3.1 Recipe
for the Production of Wheat-Cassava Bread 35
4.1 Proximate
Composition and Energy Value of Wheat and Cassava Flour 52
4.2 Functional
Properties of Wheat and Cassava Flour 64
4.3 Proximate
Composition and Cyanide Content of Wheat-Cassava Bread
baked with 10% Cassava Flour 78
4.4 Proximate
Composition and Cyanide Content of Wheat-Cassava Bread
baked with 15%
Cassava 79
4.5 Proximate
Composition and Cyanide Content of Wheat-Cassava Bread
baked with 20%
Cassava Flour 80
4.6 Physical
Properties of 10% Wheat-Cassava Bread Samples 95
4.7 Physical
Properties of 15% Wheat-Cassava Bread Samples 96
4.8 Physical
Properties of 20% Wheat-Cassava Bread Samples 97
4.9 Sensory
Properties of 10% Wheat-Cassava Bread Samples 104
4.10 Sensory Properties of 15% Wheat-Cassava
Bread Samples 105
4.11 Sensory Properties of 20% Wheat-Cassava
Bread Samples 106
LIST OF FIGURES
3.1 A
Flow Chart Demonstrating the Processing of Cassava to High Quality
Cassava
Flour (HQCF) (Eriksson,
2013) modified 33
3.2 Flow Chart for the Production of Wheat-Cassava
Bread 36
LIST OF PLATES
3.1 Sample Tubers of the Improved Cassava
Varieties 37
3.2 Bread from 10 – 20% Wheat-NR 87184
Cassava Flour 37
3.3 Bread from 10 – 20% Wheat-TMS 0593
Cassava Flour 38
3.4
Bread from 10 – 20% Wheat-UMUCAS 36
Cassava Flour 38
3.5
Bread from 10 – 20% Wheat-UMUCAS 37
Cassava Flour 39
3.6 Bread from 10 – 20% Wheat-UMUCAS 38
Cassava Flour 39
3.7 Bread from 10 – 20% Wheat-Nwanyi Oji
Cassava Flour 40
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND
OF THE STUDY
Bread
is one of the oldest prepared and most widely consumed foods, serving as the
staple food of several societies and regions (Akobundu, 2007) including Africa
and Europe, contrary to the East Asian society where rice is the staple
(Komlaga et al., 2012). Bread is
defined as a food of any size, shape or form and consists of dough made from
flour and water, with or without other ingredients, which have been fermented
by yeast or otherwise leavened and subsequently baked or partly baked
(Akobundu, 2006; Adeniji, 2013). Due to urbanization, increased wealth and
changes in lifestyle, bread and other bakery products’ consumption in Nigeria
is increasing. Leavened wheat bread has become a favourite food of many
households in developing countries which may be attributed to increasing
populations, urbanization and changing food habits (Onabola et al., 2003).
Principally,
high quality breads in terms of large volume, good crust and crumb texture is
produced from wheat flour (Okaka, 1997). Unlike cassava, wheat does not grow
well under tropical conditions like in Nigeria. Hence, Nigeria depends Ayo and
Nkama, 2004). on foreign countries for the importation of wheat (Ohimain,
2014). Following the high cost of wheat importation, bread becomes expensive in
tropical countries, including Nigeria (Akubor and Obiegbuna, 2014).
The
increased demand for bread with concomitant high cost of wheat importation has
prompted the quest for substitutes for wheat in bread baking (The Nigerian
government has evolved policies to curb the expensive wheat importation and the
attendant economic losses using the composite flour technology, where most of
the studies on wheat flour substitution centered principally on the root
crops/tubers, especially cassava (Iwe, 2015). Different root tubers for flour
composites perform differently in their functionality, and also favour
different bread quality properties differently. Among the different wheat flour
substitutes, the federal government policies have only been clearly vocal about
the use of cassava flour. The high interest in the use of cassava flour in
partial wheat flour replacement is because of its many economic and processing
prospects (Nwosu, 2007). The cassava flours incorporated into the bread
formulations are referred to as high quality cassava flour (HQCF), a flour
produced from wholesome freshly harvested and rapidly processed cassava roots.The
different levels of cassava in the partial wheat replacement in the composite
flour policies range between 5% and 40% (Adeloye, 2012; Iwe, 2015).
The
adoption of high yielding cassava varieties and the resulting increase in yield
have shifted the problem of the cassava sector from supply to demand issues,
such as finding new uses and markets (Echebiri and Edaba, 2008). This has led
to intensive research on the use of its flour/starch in composite with wheat
for the development of bread and other bakery products, pastries and
confectioneries, and most recently pasta products (Nweke et al., 2002; Oladunmoye et
al., 2004; FIIRO, 2006; Nwabueze and Anoruoh, 2009).
Cassava
(Manihot esculenta) which is also called manioc, native to South
America, is extensively cultivated as an annual crop in the tropical as well as
subtropical regions for its edible starchy, tuberous root, a major source of
carbohydrates (Clifton and Keogh 2016). Cassava grows well under tropical
conditions. Cassava is drought tolerant, requires limited land for cultivation
and grows well in poor soils (Aniedu and Omodamiro, 2012). It is a staple food
in developing world (FAO, 1995; Agunbiade et
al., 2017), the third-largest source of food carbohydrates in the world and
one of the most drought-tolerant crops, capable of growing on marginal soils.
Nigeria has comparative advantage in the cultivation of cassava. Cassava is vital
to the economy of Nigeria, as Nigeria is the world's largest producer of
cassava (Agunbiade et al., 2017).
In Nigeria where it is
consumed extensively as the major staple food, cassava is known among the Igbo,
Yoruba and Hausa tribes as ‘akpu’, ‘ege’ and ‘rogo’ respectively. In Nigeria
and several other West African countries, including Ghana, Benin, Togo, Ivory
Coast, and Burkina Faso, cassava tuber is converted into different traditional
foods such as garri, fufu, lafun and tapioca. Cassava contains anti-nutritional
factors and therefore must be properly processed before it is eaten. Improper
processing of cassava can leave residual cyanide enough to cause acute cyanide
toxicity, goiters, ataxia or partial paralysis (Agunbiade et al., 2017). The fermentation processes involved in these cassava
derived foods reduce the level of antinutrients, making cassava safer for human
consumption (Agunbiade and Adanlawo, 2007; Oboh and Oladunmoye, 2007).
It
is well known in Africa that cassava’s rapid post-harvest deterioration is one
of the constraints to its utilization. Once harvested, cassava roots are highly
perishable and when stored, rapid physiological and microbiological
deterioration occur. Moreover, there is often a considerable stigma against
cassava, owing to the glucoside that can be toxic unless detoxified by
processing. There is an occasional report of death due to consumption of
cassava roots (Sanni et al., 1998).
The two major varieties grown in Nigeria are the sweet and bitter varieties,
which are classified on the basis of the cyanogenic glucoside contents of their
roots (Erhabor and Emokaro, 2007). The
choice of cassava variety for processing into different industrial products
also depends on their glycogenic glucoside content. It was also discovered that
farmers often prefer the bitter varieties because they deter pests, animals,
and thieves (Linley et al., 2002). Often times, the
locally grown cassava varieties in the tropics face the challenge of cassava
mosaic disease (CMD) and other agronomic challenges. Inspite of these major
limitations, the commendable success of cassava as a choice staple root crop by
farmers within the sub-region can be largely attributed to the development of
varieties with improved characteristics for Africa’s agro-ecologies. Cassava
production in Nigeria increased as a result of development of improved
varieties by the National Root Crops Research Institute (NRCRI) Umudike and
International Institute of Tropical Agriculture (IITA), Ibadan, who embarked on
extensive research activity on cassava and have developed cassava cultivars
that have been adopted and released into villages in Sub Saharan African
countries (Kormawa et al., 2003).
Thus, cassava cultivars with about 110 different names including the cassava
mosaic disease resistant varieties are currently grown in the semiarid zones of
West Africa. The CMD-resistant varieties are being said to be those commonly
utilized today for processing into vital industrial products, top among which
is the high quality cassava flours suitable for baking (Iwe, 2015).
Cassava
flour is one of the derivatives from cassava roots whose processing technology
is cheaper and easier than cassava starch production, besides its less
consumption of water and energy and production of smaller quantity of
by-products and waste (Abass et al., 1998; Aristizábal et al., 2017). The suitability of
different flours for baking depends on their functional properties. Cassava in
the form of starch and flour is increasingly being used as a raw material for
processing into a range of food and this is because it has been shown to
possess desirable characteristics in the food industry. However, certain
properties of cassava flour and starch, such as physical, chemical, functional
properties and thermal parameters are important for their being useful in food
industry. Some functional characteristics have been reportedly correlated with
certain key qualities of the product produced from such flours. For instance,
water-binding and absorption capacities, dispersibility, swelling power, and
solubility have a bearing on the carbohydrate quality and affect viscosity and
gelling ability of flour (Oladunmoye et
al., 2004). Therefore, the present study was aimed to assess the functional
properties of flours from the improved cassava varieties and their consequent
impact in wheat–cassava bread production.
1.2 STATEMENT OF PROBLEMS
Wheat
and corn and their flours imports represent a major burden on the economy of
importing countries including trade imbalance, overdependence on foreign foods,
loss of foreign exchange, food insecurity, as well as displacement of local
food, with detrimental effects on the agricultural and technological
development of these regions (Ohimain, 2014). The need for strategic
development and use of local resources for producing low cost foods, such as
bread and baked foods has been recommended by organizations such as the Food
and Agriculture Organization of the United Nations (FAO), the International
Center for Tropical Agriculture (CIAT), the International Institute of Tropical
Agriculture (IITA) and the Federal Institute for Industrial Research Oshodi
(FIIRO). Inclusion of cassava flour as composite for production of foods such
as noodles, breakfast cereals, cookies, breads, cakes, pastries, muffins and
doughnuts among others could reduce costs and increase the production of these
products locally (Oyewole, 2002; Falade and Akingbala, 2009; Akinlonu, 2011).
Measures to promote the use of cassava flour in tropical countries,
particularly cereals importing countries, remain active. However, its
implementation and consolidation has been linked to the sufficient availability
of suitable locally sourced cultivars.
The
breeding program by NRCRI/IITA which resulted in the production of several
elite genotypes altered the botanical characteristics of the newly cultivars.
This may have also altered the functional properties of the cassava product
(flour) processed from these newly improved cultivars. There tend to be less
research on this possible change in varieties and variation in the functional
properties of each cultivar studied could be of significance in determining
their suitability for different products. Thus, this led to the study,
functional properties of the newly improved cassava cultivars and its quality
in bread production. Furthermore, even though cassava flour has been
incorporated in wheat composite for bread, development of new cassava varieties
need to be evaluated in bread making and other physical and chemical
properties. This is the thrust of this work.
1.3 JUSTIFICATION
The
success of the present study could encourage industrialists and entrepreneurs
in using high quality cassava flour in composite bread making. The success of
this study will also help restore confidence in the use of increased cassava flour
and/or products. This is expected to help reduce the economic burden of wheat
flour importation on the shoulders of master bakers. In Nigeria, it is the most
important root crop in terms of food security, job creation, and income
generation for crop producing households. This will be- of great advantage to
rural producers and hence their economic power.
1.4 OBJECTIVE OF THE STUDY
The
general objective was to determine the chemical and functional properties of
improved cassava varieties and their application in composite bread production.
The
specific objectives of the study were to:
1. Produce
flour from five newly improved cassava varieties and a local variety.
2. Determine
the proximate composition, HCN content and functional properties of these
cassava flours.
3. Formulate
wheat-cassava composite flours.
4. Produce
bread from the composite flours.
5. Determine
the proximate composition and Hydrogen Cyanide content in the bread samples.
6. Determine
the physical properties of the composite bread samples.
7. Determine
the sensory properties of the bread made from the composite flours.
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