ABSTRACT
The study was undertaken to assess the production and quality evaluation of biscuits from composite flours of pearl millet, sorghum, and wheat. Pearl millet and sorghum flours were produced from whole peal millet and sorghum grains (red and white cultivars) and then incorporated at 5%, 20%, 50%, and 80% levels in wheat flour. Functional properties of the composite flours were determined. Bulk density and wettability of the composite flours significantly (p<0.05) decreased (from 0.61−0.46 and 70.00−63.00 respectively), while geletation temperature, water absorption, oil absorption, emulsion and foaming capacities, and swelling index significantly (p<0.05) increased (from 68.67−92.33, 1.67−2.37, 1.30−1.96, 8.56−35.03, and 1.11−1.42 respectively). Biscuits were prepared from the composite flour samples (including 100% wheat, 100% pearl millet, and 100% sorghum flours). The weight, spread ratio, spread factor, and break strength of the biscuits significantly (p<0.05) increased and were in the range of 11.86−19.84g, 4.08−9.67, 60.43−143.15%, and 73−137g respectively. The results of the proximate analyses (%) of the composite flour biscuits show that moisture, ash, crude fiber, protein, and fat contents significantly (p<0.05) increased with increasing levels of pearl millet and sorghum flours substitution and were in the range of 4.79−5.17, 4.00−4.35, 1.67−2.71, 6.00−6.77, and 22.44−22.55 respectively, while the carbohydrate content significantly (p<0.05) decreased from 60.51−5.47. The B1, B2, and B3 contents of the biscuits significantly (p<0.05) increased and were in the range of 0.162−0.196, 0.039−0.051, 0.917−1.107 mg/100g respectively, but there was no significant (p>0.05) increase in the Vitamin A content (317−320.77mg/100g). The phytate content of the biscuits significantly (p<0.05) increased with increasing levels of pearl millet and sorghum flours substitution and was in the range of 0.060–0.08mg/100g, whereas there were no detectable levels of HCN, alkaloid, and tannin found in the biscuits. Ca, K, and Na contents significantly (p<0.05) increased (from 16.70−34.07, 149.83−221.00, 9.02−11.96 mg/100g respectively), while Mg and P significantly (p<0.05) decreased (from 55.97−34.83 and 184.25−131.17 respectively). The biscuits produced from the composite flours were organoleptically acceptable and compared favourably with the control; however, BWR80 (biscuits produced from a composite of 20% wheat flour and 80 % red sorghum flour) gave nutrient-rich biscuits with a significantly (p<0.05) higher protein content, with desirable physical characteristics; its utilization may be nutritionally beneficial to consumers.
TABLE OF
CONTENTS
Title page i
Declaration ii
Certification
iii
Dedication
iv
Acknowledgements
v
Table of contents
vi
List of Tables
xii
List of Figures
xiii
List of Plates
xiv
Abstract
xv
CHAPTER 1: INTRODUCTION 1
1.1 Background of the Study
1
1.2 Statement of Problem 3
1.3 Objective of the Study 4
1.3.1 General objective of the study 4
1.3.2 Specific objectives of the study 4
1.4 Justification of the Study 4
CHAPTER 2: REVIEW OF RELATED LITERATURE 5
2.1 Origin, Distribution, and Diversity of Cereals 5
2.2 General Structure and Chemical Composition
of Cereal Grain 6
2.3 Proximate Composition of Cereals 15
2.3.1 Moisture content 15
2.3.2 Ash content 15
2.3.3 Protein content 16
2.3.4 Lipid content 18
2.3.5 Carbohydrates 19
2.3.5.1 Starch 19
2.3.6 Fiber content 21
2.4 Anti-nutritional and Toxic Components 22
2.4.1 Phytates 22
2.4.2 Poly-phenolic compounds 23
2.4.3 Protease inhibitors 25
2.5 Minerals 25
2.6 Vitamins 26
2.7 Utilization of Cereals for Various Food Products 26
2.8 Manufacturing of Biscuits 28
2.8.1
Steps in processing biscuits 29
2.8.1.1 Preparing and measuring the ingredients
29
2.8.1.1.1 Flour 29
2.8. 1.1.1.1 Milling of flour 29
2.8.1.1.1.1.1
Traditional methods 30 2.8.1.1.1.1.2 Mechanical methods 31
2.8.1.1.1.2 Cereal hardness phenomenon 33
2.8.1.1.1.3 Types of wheat flours 34
2.8.1.1.1.3.1 Whole wheat flour 34
2.8.1.1.1.3.2 White flour 35
2.8.1.1.1.3.3 Bread flour 35
2.8.1.1.1.3.4 All-purpose flour 35
2.8.1.1.1.3.5 Pastry flour 36
2.8.1.1.1.3.6 Cake flour 36
2.8.1.1.1.3.7 Self-rising flour 36
2.8.1.1.1.3.8 Enriched flour 36
2.8.1.1.1.3.9 Non wheat flours 37
2.8.1.1.1.3.10 Composite flours 37
2.8.1.1.1.4 The criteria of good biscuits flour
39
2.8.1.1.1.4.1 Suitable protein quality 39
2.8.1.1.1.4.2 Reasonably low protein quality 40
2.8.1.1.1.4.3 Medium to low α-amylase activity 40
2.8.1.1.2 Sweeteners 41
2.8.1.1.2.1 Granulated sugar 42
2.8.1.1.2.2 Liquid sugars 42
2.8.1.1.2.3 Brown sugar (soft sugar) 42
2.8.1.1.3 Liquids 43
2.8.1.1.4 Fats and oils 43
2.8.1.1.5 Eggs 45
2.8.1.1.6 Salt 45
2.8.1.7 Flavour 46
2.8.1.2 Mixing batters and dough 46
2.8.1.2.1 Factors affecting mixing 47
2.8.1.2.1.1 Temperature of the ingredients 47
2.8.1.2.1.2 Kind, quality, and proportions of
ingredients 47
2.8.1.2.1.3 Order, method, and amount of mixing 48
2.8.1.2.1.4 Size and shape of mixing equipment 48
2.8.1.2.2 Methods for mixing batters and dough 49
2.8.1.2.2.1 The pastry method 49
2.8.1.2.2.2 The conventional cake method 49
2.8.1.3 Kneading and forming of biscuits 49
2.8.1.4 Baking of biscuits 50
2.8.1.4.1
Changes that occur during the baking of flour
mixtures 53
2.8.1.5
Packaging and storage 54
CHAPTER
3: MATERIALS AND METHODS
56
3.1
Materials 56
3.2
Methods 56
3.2.1
Preparation of sorghum and millet flours 56
3.2.2
Preparation of composite flour 57
3.3
Determination of the Functional Properties of Sorghum-Wheat and
Millet-Wheat
Composite Flours 59
3.3.1 Bulk density 59
3.3.2
Swelling index 59
3.3.3 Water absorption capacity 60
3.3.4 Emulsion capacity 60
3.3.5 Foaming capacity (FC) 60
3.3.6
Oil absorption capacity (OAC) 61
3.3.7
Wettability 61
3.3.8
Gelatinization point 62
3.4
Preparation of Biscuits from Sorghum-Wheat
and Pearl Millet-Wheat Composite Flours
62
3.5 Determination
of the Physical Properties of Sorghum-Wheat Flour and
Pearl Millet-Wheat Flour Biscuits 65
3.5.1 Weight 65 3.5.2
Diameter 65
3.5.3 Spread ratio 65
3.5.4
Spread factor 65
3.5.5
Break strength 65
3.6
Determination of the Proximate Composition of Sorghum-Wheat Flour and
Pearl
Millet-Wheat Flour Biscuits 66
3.6.1 Moisture content 66
3.6.2 Ash content 67
3.6.3 Fat content 67
3.6.4 Crude fibre 68
3.6.5 Crude protein 69
3.6.6 Determination of carbohydrate 70
3.7 Determination of Vitamins 71
3.7.1 Determination of riboflavin (Vitamin B2) 71
3.7.2 Determination of thiamin (Vitamin B1) 71 3.7.3 Determination of niacin 72
3.7.4 Determination of vitamin A 72
1.
3.8 Determination of Phytochemicals 73
3.8.1 Determination of alkaloid 73
3.8.2 Determination
of tannin 73
3.8.3 Determination of phytate content 74
3.8.4 Determination of HCN 74
3.9 Determination of Minerals 75
3.9.1 Determination of calcium and magnesium 76
3.9.2 Determination of potassium and sodium 77
3.10 Sensory Evaluation 78
3.11 Statistical Analysis 78
CHAPTER 4: RESULTS AND
DISCUSSION
79
4.1 Functional Properties of Sorghum-Wheat and
Pearl
Millet-Wheat Composite Flours
79
4.1.1 Bulk density 79
4.1.2 Water absorption 82
4.1.3 Oil absorption 84
4.1.4 Emulsion capacity 85
4.1.5 Foaming capacity 86
4.1.6 Swelling index 87
4.1.7 Wettability 88
4.1.8 Gelation capacity 89
4.2
Antinutrient Composition of the Biscuits Produced from Wheat Flour (Control)
and Millet Supplemented Wheat Composite Flours 91
4.2.1 Phytate 91
4.3
Proximate Composition of the Biscuits Produced from Wheat Flour (Control)
and Millet Supplemented Wheat Composite Flours 95
4.3.1 Moisture content 95
4.3.2 Protein content 97
4.3.3 Fat content 99
4.3.4 Fibre content 100
4.3.5 Ash content 101
4.3.6 Carbohydrate content 102
4.4
Mineral Composition of the Biscuits Produced from Wheat Flour (Control)
and Millet Supplemented Wheat Composite Flours 104
4.4.1 Calcium 104
4.4.2 Magnesium 106
4.4.3 Potassium 107
4.4.4 Sodium content 109
4.4.5 Phosphorus 110
4.5
Vitamin Composition of the Biscuits Produced from Wheat Flour (Control)
and Millet Supplemented Wheat Composite Flours 112
4.5.1 Vitamin A 112
4.5.2 Thiamin (Vitamin B1) 114
4.5.3 Riboflavin (Vitamin B2) 115
4.5.4 Niacin (Vitamin B3) 116
4.6 Physical
Properties of the Biscuits Produced from Wheat Flour (Control)
and Millet Supplemented Wheat Composite
Flours 118
4.6.1 Weight 118
4.6.2
Spread ratio 120
4.6.3
Spread factor 121
4.6.4 Break strength 122
4.7
Sensory Evaluation Results of the Biscuits Produced from Wheat Flour (Control)
and
Millet Supplemented Wheat Composite Flours 125
4.7.1 Appearance 125
4.7.2 Taste 129
4.7.3 Aroma 130
4.7.4 Texture 131
4.7.5 Crispiness 132
4.7.6 General acceptability 133
CHAPTER
5: CONCLUSION AND RECOMMENDATION 138
5.1 Conclusion 138
5.2 Recommendation 139
References 140
Appendices 155
LIST OF TABLES
2.1: Key characteristics of sorghum varieties
from
Queensland and New South Wales
14
3.1: Formulation of composite flour from
sorghum,
pearl
millet and wheat flour 58
3.2: Recipe for sorghum-wheat flour and pearl
millet-wheat
flour biscuits
64
4.1: Functional properties of sorghum-wheat and
pearl
millet-wheat composite flours 81
4.2: Results of the antinutrients in biscuits
from sorghum-wheat
and pearl millet-wheat composite flours 93
4.3 Results
of the proximate composition of biscuits from
sorghum-wheat and pearl millet-wheat
composite flours 96
4.4: Results of the minerals in biscuits from
sorghum-wheat
and
pearl millet-wheat composite flours 105
4.5:
Results of the vitamins in biscuits made from sorghum-wheat and
pearl millet-wheat composite flours 113
4.6:
Results of the physical characteristics of biscuits made from
sorghum-wheat and pearl millet-wheat
composite flours 119
4.7:
Results of the sensory parameters of biscuits produced from
sorghum-wheat and pearl millet-wheat
composite flours 127
LIST OF FIGURES
2.1: Structure
of a pearl millet grain
9
2.2: Structure
of sorghum kernel
12
3.1: Flowchart
for the production process of wheat, pearl
millet and sorghum composite flour
biscuit 62
LIST OF PLATES
4.1: Photograph of the different biscuits
formulated
(BWC0=A;
BWP5=B; BWP20=C)
135
4.2: Photograph of the different biscuits
formulated
(BWP50=D;
BWP80=E; BWP100=F)
135
4.3: Photograph of the different biscuits
formulated
(BWW5=G;
BWW20=H; BWW50=I)
136
4.4: Photograph of the different biscuits
formulated
(BWW80=J;
BWW100=K; BWR5=L) 136
4.5: Photograph of the different biscuits
formulated
(BWR20=M,
BWR50=N)
137
4.6: Photograph of the different biscuits
formulated
(BWR80=O, BWR100=P)
137
CHAPTER 1
1.0
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The availability and utilization of the different cereal
types depend largely on climate and food
preferences—at local or regional levels. Wheat (Triticum
aestivum), a temperate crop, has been successfully
used in the production of different food products. Sorghum
bicolor is one of the important food crops in Africa. Sorghum
flour is a powerhouse of nutrition and adds a superb flavour to gluten-free baking. It is high in protein, iron, and
dietary fibre, making sorghum flour
welcome in pantries around the world. It is also high in antioxidants, which
support cardiac health. In addition, the starch and protein in sorghum take
longer than other similar products to digest. This slow digestion is
particularly helpful for those with diabetes (Adeyeye, 2016). Sorghum supplies
numerous essential nutrients in rich content (20% or more of the Daily Value,
DV), including protein, the B vitamins, niacin, thiamin and vitamin B6, and
several dietary minerals, including iron (26% DV) and manganese (76% DV). Sorghum
nutrient contents generally are similar to those of raw oats (Mutegi et al., 2010).
Millet
(Pennisetum glaucum)
is an underutilized crop in Nigeria and has good nutritional quality and could
be a good replacement source for portions of wheat flour in snacks production (Omah and Okafor, 2015). The most important species
are pearl millet, finger millet, proso millet, and foxtail millet. The major
problems in pearl millet [Pennisetum glaucum (l.) r. br.] utilisation
are the low protein quality, low protein and carbohydrate digestibilities,
presence of anti-nutritional factors and goitrogenicity (Abdalla, 2003).
However, studies have shown that pearl is generally superior to sorghum in
protein content and quality, protein efficiency ratio (PER) values, and
metabolizable energy levels. Processing of locally available cereals into
flour, which is less bulky and more stable, broadens the potential for their
utilization.
The word
biscuit is derived from the French word ‘biscuit,’ which means twice-cooked,
which gives a blueprint of biscuit-making in the early days. Fellows (1997) defined
biscuits as baked, dry, crispy products with a usually golden brown crust. Wheat flour is a
principal (main) raw material in biscuit production (Adhikari and Acharya,
2015). In addition to the wheat flour,
other ingredients used in the production of biscuits include margarine
(Shortening), sweeteners (sugar), leavening agents, eggs, milk, salt and flavors
(Adebowale et al., 2012). Biscuits
are a good vehicle for nutrition interventions as a supplementary food due to
their popularity, high nutrient density, and long shelf life, and they are
ready-to-eat (Mahmoud, 2003). Within the last
two and half decades, in the bakery world, the use of composite flour has evolved,
especially for the production of bread and baked
products in many wheat importing countries (Mepba et
al., 2007).
The term ‘composite flour’ means the
combination of two or more types of flour in a given ratio for baking. The superiority of wheat flour over other cereals is due to the
presence of gluten (Adhikari and Acharya, 2015), and in the biscuit types where
the biscuit strength
is dependent on some appropriate level of gluten development, the use of
composite flour reduces the texture of such biscuits. A slight modification of
the recipe can reduce the dough rupturing during sheeting and fragility of
biscuit samples from composite flour (Okaka and Anjekwu, 1980). The climatic
condition in Nigeria is unfavourable
for the cultivation of wheat but is suitable for other cereal like sorghum,
maize, millet, etc.; legumes (soybean, cowpeas, groundnut, Bambara nut); and vegetable (Eneche, 1999).
Furthermore, the use of any food raw material in processing depends on its
availability as well as the reduction (in terms of quantity) owing to post-harvest losses when
processed into flour, and these have led to the use of wheat flour (Ukhum and
Ukpebor, 1991). Available data from research has shown
that biscuits, as well as other pastries, could be produced from flours
obtained from locally available tropical crops such as millet, sorghum, etc.
(Adeyeye and Akingbala, 2014). Acceptable
biscuits and bread have been produced from non-wheat flour in some countries,
and among the various cereals, the best substitute for wheat in composite
flours are sorghum and millet (Mahmoud, 2003).
1.2 STATEMENT OF PROBLEM
People
who have celiac disease react to certain gluten in wheat. Presently, persons with celiac disease are
unable to consume some of the most commonly available products of the market
including breads, baked goods, and other
food products made with wheat flour; celiac disease can be treated by avoiding
of gluten ingestion (Adeyeye, 2016). The incidence of obesity is on the
increase. Consumption of nutritious snacks could help reduce protein-energy
malnutrition in school children and adults.
Developing countries are looking for an alternative to wheat to stop the
drive which costs them so much of their foreign currency. The consumption of
biscuits requires the development of an adequate substitute for wheat.
1.3 OBJECTIVE OF THE STUDY
1.3.1 General objective of the study
The general objective of this study was to process millet and sorghum (red and
white) into flour and to evaluate their
performance in biscuit-making when used as a composite
with wheat flour.
1.3.2 Specific objectives of the study
The specific objectives were to:
i)
Process millet and sorghum (red and white) into flour.
ii)
produce biscuits from composite flours of wheat and test cereal
(millet and sorghum)
iii)
Determine physical and
chemical properties of the composite biscuits and evaluate their acceptability
by consumers.
iv)
Determine the ratio of
the composite flour that gives the best biscuit.
1.4 JUSTIFICATION OF THE STUDY
A
sound knowledge and success of this work will provide information on the
locally available cereal (millet, sorghum) that gives the best biscuit when
used as a composite with wheat flour, thereby providing high-quality,
nutrient-dense substitute for 100% wheat biscuits to help tackle the problem of
poor nutrition in Nigeria.
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