ABSTRACT
This study was conducted to investigate the effects of substitution of wheat flour with three underutilised legumes and soybean flours on the pasting and physicochemical properties of the composite flour blends and biscuit crackers. Nine blends were prepared by homogenously mixing wheat, soybean and one of the three underutilized legumes in the proportion of 50:20:30, 40:20:40, 60:20:20 (for African yam bean); 40:10:50, 40:20:40, 60:10:30 (for Bambara) and 60:10:30, 40:20:40, 50:10:40 (for pigeon pea). 100% wheat flour served as control. Functional and pasting properties of the composite flour produced from wheat, soybean and three underutilized legumes (African yam bean, Bambara groundnut and pigeon pea) as well as physical, chemical and sensory properties of the cracker biscuits were determined using standard methods. There were significant differences (p<0.05) in the functional and pasting properties of the composite flours. Wheat-soy-legume composite flours showed decreased bulk density, oil and water absorption capacities, while swelling index, gelation time, foam and emulsion capacities increased with increase in addition of legume/soy flour. The peak viscosity, trough and final viscosity values of the composite flour samples were lowest in AYA (50 % wheat: 20 % soybean: 30 % African yam bean) and highest in BMC (60 % wheat:10 % soybean:30 % Bambara) ranging from 145.12RVU to 174.75RVU in BMC, 89.32-120.64RVU and 110.67-263.88RVU respectively. The result indicated that the flour blends had lower peak viscosity, trough, final and set back viscosity than the control (p<0.05). The composite flour crackers were significantly higher (p<0.05) in protein, ash, fat and fibre components than control (wheat) crackers. Addition of legume/soybean flour to wheat flour increased the protein (13.00 - 20.91 %), fat (5.0 -7.3 %), ash (1.98- 2.35%), crude fibre (2.52 -3.32 %) and energy value (377.73 - 409.08 kcal), while moisture and carbohydrate contents decreased in the composite flour biscuit cracker samples compared to control. Significant differences (p<0.05) were found in the physical dimensions of the composite flour crackers. Higher values were observed for thickness (0.61-0.78 cm), diameter (2.26-3.90 cm), weight (4.52 – 7.72 g) and spread ratio (33.73-61.97) of the crackers from flour blends compared to control with increased addition of legume/soy flour. Cracker samples showed varied degree of acceptability in terms of texture, colour, taste, odour and overall acceptability (p<0.05) compared to control. Mean sensory scores of all sensory attributes for AYC crackers (60 % wheat: 20 % soybean: 20 % African yam bean) were similar (p>0.05) to 100 % wheat crackers. The study concluded that substitution of wheat flour with legume flours up to 40% produced cracker biscuits with improved nutritional and acceptable sensory qualities. This result if widely explored, will enhance the utilization of these underutilized legumes.
TABLE OF CONTENTS
Title
page i
Declaration ii
Dedication iii
Certification iv
Acknowledgements v
Table of
Contents vi
List of
Tables x
List of Figures xi
Abstract xii
CHAPTER 1: INTRODUCTION
1.0 Background of Study 1
1.1 Statement
of Problem 2
1.2 Justification
of Study 3
1.3 Objectives
of the Study . 5
1.4 Scope
of the Study 5
1.5 Significance
of the Study 6
CHAPTER 2: LITERATURE REVIEW
2.1 Plant
Proteins 7
2.2 Wheat Flour 10
2.3 Under Utilised Crop Species 11
2.3.1 Bambara groundnut 12
2.3.1.1 Nutritive value of bambara groundnut 13
2.3.1.2 Utilisation of bambara groundnut 14
2.3.2 African yam bean 17
2.3.2.1Nutritive
value of African yam bean 18
2.3.2.2 Utilisation of African yam bean 19
2.3.3 Pigeon pea 19
2.3.3.1 Nutritive value of pigeon pea . 20
2.3.3.2 Utilisation of pigeon pea 21
2.4 Soyabean 23
2.5 Rheological Characteristics of Composite
Flours 25
2.6 Cookies 26
2.6.1 Crackers 28
2.6.2 Cookies baking 28
2.6.3 Role of flour in baking cookies 29
2.6.3.1
Flour starch 29
2.6.3.2 Flour protein 30
2.6.3.3
Flour lipids 31
2.6.3.4 Flour moisture content 31
2.6.4 Role of Sucrose in Cookies 31
2.6.5 Role of shortening in cookie production 32
2.7 Use of Composite Flour for Cookie Making 33
CHAPTER 3: MATERIALS AND METHODS
3.1 Sample Collection 38
3.2 Sample preparation . 38
3.2.1 Preparation of soy flour 38
3.2.2 Preparation of pigeon pea flour 38
3.2.3 Preparation of bambara groundnut flour 40
3.2.4 Preparation of African yam bean flour 40
3.3 Formulation of Composite Flour for
Crackers Production 40
3.4 Preparation of Crackers 43
3.5 Functional Properties Determination 47
3.5.1 Water absorption capacity 47
3.5.2 Oil absorption capacity 47
3.5.3 Bulk density 48
3.5.4 Emulsion capacity 48
3.5.5 Gelation capacity 49
3.5.6 Gelatinisation temperature 49
3.5.7 Foam capacity 49
3.5.8 Swelling Index 50
3.6 Determination of Pasting Properties of
Flour Blends 50
3.7 Determination of Physical Properties of
Crackers 51
3.8 Proximate Analysis of Crackers 52
3.8.1 Determination of moisture content 52
3.8.2 Crude protein determination 52
3.8.3 Crude fat determination 53
3.8.4 Crude fibre determination 54
3.8.5 Ash content determination 54
3.8.6 Carbohydrate content determination 54
3.8.7 Energy determination 55
3.9 Sensory Evaluation 55
3.10 Statistical Analysis 55
CHAPTER 4: RESULTS AND DISCUSSION
4.1 Functional Properties of Composite Flour
Blends 57
4.2 Pasting Properties of Composite Flour
Blends 63
4.3 Physical Properties of Crackers 68
4.4 Proximate Composition of Crackers 71
4.5 Sensory Characteristics of Crackers 74
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 79
5.2 Recommendations 79
References 81
LIST OF TABLES
3.1
Composite Flour Blend Proportions 44
3.2 Recipe for Cracker Biscuits
Production 45
4.1 Functional Properties of
Wheat and Under-utilised
Legumes Flour Blends 58
4.2 Pasting Properties of Wheat
and Under-utilised
Legumes Flour Blends 64
4.3 Physical
Properties of Crackers produced from Wheat,
Soyabean
and Under-utilised Legumes Flour Blends 70
4.4 Proximate
Composition of Crackers produced from Wheat,
Soybean
and Under-utilised Legumes Flour Blends 72
4.5 Sensory
Properties of Crackers produced from Wheat,
Soybean
and Under-utilised Legumes Flour Blends 76
LIST OF FIGURES
3.1 Flow Chart for the Production
of Pigeon pea Flour. 39
3.2 Flow Chart for the Production
of Bambara Groundnut Flour 41
3.3 Flow Chart for the Production
of African Yam Bean Flour 42
3.4 Flow
Chart for Crackers Production 43
CHAPTER 1
INTRODUCTION
1.0 BACKGROUND OF THE STUDY
Consumption of snacks (small amount of food
that is eaten between main meals instead of a meal) has been on the increase as
a result of urbanization and increase in the number of working women. Food
based industry can exploit this development by fabricating nutritious snack
foods.
Cookies
are flat, dry, sweet biscuits. The word “biscuit” comes from the French word
‘’biscuit’’, twice-cooked, and is a literal description of what happened in the
early days of biscuit making. Research
in the use of tropical crops has shown that biscuits and other pastries such as
meat-pie, cookies and cakes etc could be made from flours of locally available
crops such as sweet potato, cassava, corn, rice, millet, sorghum etc (IITA,
1985). Biscuits have become one of the
most desirable snacks taken by both young and elderly people to provide energy
(Okaka, 1997). It represents the largest category of snack item among baked
food products through-out the world (Pratima and Yadava, 2000). It is produced
from a mixture of flour and water which may contain fat, sugar and other
ingredients mixed together into dough which is rested for a period and passed
between rollers to make a sheet (Mohamed, 2000; Olaoye et al., 2007).
The
consumption of biscuits is steadily increasing in Nigeria. Although they are
not considered as a staple food as in bread, they are ready to eat and convenient food
products, containing digestive and dietary principles of vital importance
(Kulkarni, 1997). It is however, relatively expensive, being
made from imported wheat that is not cultivated in the tropics for climatic
reasons coupled with its low protein content (Akpapunam and Darbe, 1994; Aloba, 2001). Wheat
importation represents an immense drain on the economy while also suppressing
and displacing indigenous cereals, with a resultant detrimental effect on
agricultural and technological development. In many countries, biscuits are
prepared with fortified or composite flour to increase its nutritive value
(Gonzalez-Galan et al., 1991). The
supplementation or fortification of biscuits and other baked goods with
nutritious and inexpensive dietary staples derived from grain legumes has
gained momentum particularly in regions where protein utilization is
inadequate. This is because the nutritional value of grain legumes is related
to their high protein content and their high lysine content which makes them
good complements to cereal proteins which are low in lysine but high in the
sulphur containing amino acids that are deficient in legume proteins
(Ihekoronye and Ngoddy, 1985; Akapo et al., 1995; Nkama et al., 2001).
Ideally, the ingredients for the production of low cost complementary baked
goods must be derived from dietary staples available and affordable in the
region of interest.
1.1 STATEMENT
OF PROBLEM
In many
parts of sub-Saharan Africa and most especially Nigeria, advancing prosperity
and urbanization coupled with tremendous increase in population in recent years
have led to an increase in the consumption of wheat-based products especially
biscuits, cakes and breads. However, the production of wheat in Nigeria is
extremely low and far below domestic requirements leading to the increase in
wheat importation; as a result, the cost of these products are fairly high.
Composite flour technology has been used as a means for extending scarce
supplies of wheat or corn used in the production of bread or other baked goods
in most wheat importing countries within the last two and half decades thus
encouraging the agricultural sector and reducing wheat importation in many
developing countries. The low protein content of the wheat flour, which is the
most important ingredient used for the preparation of conventional snacks or
bakery products has been of great concern to food scientists and nutritionists
in its utilization. Thus the need to supplement or fortify baked goods with
nutritious and inexpensive dietary staples derived from grain legumes has
gained momentum particularly in regions where protein utilization is
inadequate. This is because the nutritional value of grain legumes is related
to their high protein content and their high lysine content. Availability, cultural acceptability and increased
nutritional potentiality are required in compositing flour blends. Ideally, the
foods produced should look and taste like traditional foods. This need for
strategic development and use of inexpensive local resources in the production
of popular foods such as cookies has been recognized by organizations such as
the Food and Agricultural Organization (FAO) and the International Institute
for Tropical Agriculture (IITA).
Such inexpensive local
resources are obtained from other cereals, legumes, tubers, and root crops, for
example maize, acha, sorghum, rice, soybean, bambara groundnut, pigeon pea,
African yam bean, cassava, sweet potato, potato, and plantain (Akubor, 2003;
Echendu et al., 2004; Olaoye et al., 2007; Chinma and Gernah, 2007;
Chinma et al., 2007; Oladunmoye et al., 2010; Chinma et al., 2011; Abioyeet al., 2011; Oluwamukomi et
al., 2011; Chinma et al., 2012; Laura et
al., 2012; Igbabul et al., 2015).
1.2 JUSTIFICATION OF THE STUDY
Enrichment of cereal based food with other
protein source such as legumes has received considerable attention. The use of
cereal-legume based food has long been advocated as alternative protein and
energy source for infant and young children food products (Mensah and Tomkins,
2003). It is evident that when cereals and legumes are judiciously selected and
combined desirable pattern of essential amino acids of high biological value is
obtained (Nnam, 2001). Cereals (maize, millet, acha, sorghum, rice, wheat etc.)
are deficient in essential amino acids like lysine and tryptophan (Lasekan, 1994).
Legumes are deficient in sulphur containing amino acids like methionine and
cystine, but rich in tryptophan and lysine.
Also of
interest is an upsurge in the number of well-informed consumers who put into
consideration the health and nutritional benefits of food products they
consume. This has contributed to the stimulation of research into alternative
food crops with functional or health benefits to be incorporated as composite
flour in wheat-based bakery products. With increased awareness of a healthy
lifestyles based on consumption of functional foods, confectionaries containing
multi-grain or other functional ingredients especially from legumes will
increasingly become more important in the bakery industry and in the emerging
market (Dewettinck, 2008). The high protein content of legume supplemented
crackers would be of nutritional importance in most developing countries, such
as Nigeria, where many are undergoing changing lifestyle factors and nutrition
transition due to increasing urbanisation and can hardly afford high proteinous
foods because of their expensive costs. There is therefore the need to develop
a different approach to offer the weary consumers the opportunity to feed on
improved formulations with substantive health benefits from wheat-legume
combinations.
This study is one of the efforts to promote the
use of composite flours in which flour from locally grown legume crops and
soybean with high protein content shall be used to produce protein-enriched composite
flour. Thus, the aim of this work is to produce and evaluate the optimum
proportion of three underutilized legumes (bambara groundnut,
African yam bean and pigeon pea) and soybean flour for
production of composite flour compared with wheat flour in the
preparation of crackers on the basis of physical, sensory and nutritional
quality characteristics.
1.3 OBJECTIVES
OF STUDY
The
general objective of this study was to evaluate the quality
of flour blends of wheat, underutilized legumes (African
yam bean, bambara groundnut and pigeon pea) and
soybeans and to also determine the suitability of the blends in the production
of cracker biscuits.
The specific
objectives of this study are to:
i.
produce individual flours
from wheat, bambara groundnut, African yam bean, pigeon pea seeds.
ii.
produce flour blends from
wheat, underutilized legumes (bambara groundnut, African yam bean and pigeon
pea) and soybean flours.
iii.
determine the functional
and pasting properties of the composite flour blends
iv.
produce crackers from the
composite flour blends
v.
determine the proximate constituents of
the crackers
vi.
determine physical properties of the
crackers and
vii.
evaluate the sensory characteristics of
the crackers.
1.4 SCOPE
OF STUDY
The
study was limited to the production of composite flours from wheat, three
underutilized legumes (Bambara groundnut, African yam bean and pigeon pea) and
soy bean, production of cracker biscuits from the composite flour blends and
the determination of the physical, functional, nutritional and sensory
characteristics of the flours and crackers produced.
1.5 SIGNIFICANCE OF STUDY
The
result of this study will open up another possible application for these
underutilized legume flours and flour blends. It is hoped that these legumes
will hold the key to qualify protein supply on mutual supplementation principle.
It will improve the nutritional value and protein content of crackers thus helping
to alleviate the problem of protein energy malnutrition prevalent among
children and adolescents in Nigeria and other sub-Saharan African countries.
The acceptability of crackers produced from these legume flours will go a long
way to reduce the drain on the economy resulting from importation of wheat
while promoting the use of indigenous raw materials and dietary
diversification.
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