ABSTRACT
Soybean flour was produced from soybean seeds and blended with wheat flour at different proportions. The composite flour samples were analyzed for the functional properties. The flour samples were used to produce bread and cookies samples which were analyzed for the proximate composition, mineral content, physical properties, microbial quality and sensory properties. The functional properties of flour samples ranged from 0.80 to 1.43 g/ml, 1.91 to 2.31 g/ml, 1.88 to 1.98 g/ml, 1.23 to 1.57, 51.07 to 60.39 ℃ and 1.08 to 1.39 min/sec for bulk density, oil absorption capacity, water absorption capacity, swelling index, gelatinization temperature and wettability respectively. The results obtained for the baked products revealed that the proximate composition ranged from 8.35 to 10.39%, 12.06 to 15.30%, 3.27 to 5.23%, 2.09 to 3.24%, 2.41 to 4.02%, 63.88 to 69.64% and 355.8 to 363.75 Kcal in bread, and from 8.79 to 10.34%, 10.89 to 13.29%, 3.11 to 9.69%, 1.32 to 1.66%, 1.07 to 3.29%, 63.37 to 73.28% and 364.65 to 393.47 Kcal in cookies for moisture content, crude protein, fat, crude fibre, ash, carbohydrate and energy value respectively. The mineral composition of bread and cookies increases with increased substitution of wheat flour with soybean flour and ranged from 40.23 to 55.22 mg/100g, 15.17 to 30.32 mg/100g, 30.22 to 50.44 mg/100g, 13.65 to 27.29 mg/100g and 6.77 to 8.49 mg/100g in bread and from 26.62 to 45.52 mg/100g, 40.05 to 50.75 mg/100g, 23.19 to 34.80 mg/100g, 18.21 to 26.07 mg/100g and 3.82 to 8.10 g/100g in cookies for calcium, phosphorus, magnesium, potassium and sodium respectively. For the bread samples, physical properties ranged from 250.91 to 320.15 g (weight), 168.02 to 244.88 cm3 (loaf volume), 0.52 to 0.96 cm3/g (specific volume) and 0.42 to 0.61 cm (oven spring). In the cookie samples, it ranged from 18.98 to 26.69 g (weight), 0.62 to 0.98 cm (thickness), 9.04 to 9.89 kg (break strength) and 5.08 to 5.33 cm (diameter). The total fungal count (TFC) of the bread and cookie samples were equal to the number of total viable microbial count observed and ranged from 0 to 5 cfu/g in bread and 3 to 24 cfu/g in cookies. No coliform growth was detected in any of the bread and cookie samples. In sensory attributes, appearance ranged from 5.40 to 7.55 and 6.45 to 7.10; taste from 4.40 to 7.50 and 6.05 to 8.30; texture from 5.6 to 7.30 and 5.80 to 7.15; aroma from 4.75 to 6.85 and 5.60 to 7.80; general acceptability from 5.20 to 7.75 and 6.65 to 7.85 in bread and cookie samples respectively. Although substitution of some proportion of the wheat flour with small proportions of soybean flour showed no significant difference (P 0.05) in acceptance, higher proportions of soybean flour reduced the acceptability. The results shows that partial substitution of wheat flour used in baking with soybean flour could improve the nutritional quality of bread and cookies while providing a cheap alternative to the mainly imported wheat 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 problems 3
1.3 Justification
of study 3
1.4 Objectives
of the study 4
CHAPTER 2:
LITERATURE REVIEW
2.1 Bread 5
2.1.1
Basic ingredients of bread 5
2.1.2 Methods
of bread making 9
2.1.3
Main steps in bread making 11
2.1.4 Nutritional
value of bread 13
2.2
Cookies 14
2.2.1 Ingredients for production of cookies/biscuit 15
2.2.2
Method of cookie production 19
2.2.3
Nutritional value of cookies 19
2.3 Wheat
20
2.3.1 Composition
of whole wheat 21
2.3.2 Economic
importance of wheat 23
2.3.3 Uniqueness of wheat in baking 24
2.3.4 Impact of wheat importation on the
economy 25
2.3.5 Possible ways of cutting high wheat import
bill 25
2.4 Legumes: An overview 26
2.4.1 Nutritional,
health and economic importance of legumes
27
2.5
Soybean 29
2.5.1
Production
of soybeans 30
2.5.2
Nutritional
composition of soybean 31
2.5.3 General
utilization of soybean 32
2.5.4 Health benefits of
soybean 34
2.5.5
Major anti-nutrients in soybean 34
CHAPTER 3:
MATERIALS AND METHODS
3.1 Source
of materials 36
3.2
Sample preparation 36
3.2.1
Processing of soybean into flour 36
3.3
Determination of functional
properties of flour samples 40
3.3.1 Bulk
density 40
3.3.2 Water
and oil absorption capacity 40
3.3.3 Swelling
index 40
3.3.4 Gelatinization
temperature 41
3.3.5 Wettability 41
3.4 Production of baked
products 42
3.4.1 Production of
bread 42
3.4.2 Production
of cookies 42
3.5
Proximate analysis 47
3.5.1 Moisture content determination
47
3.5.2 Ash content determination 47
3.5.3 Crude fibre determination 48
3.5.4 Fat determination 48
3.5.5 Crude protein determination
49
3.5.6 Carbohydrate
determination 50
3.5.7
Determination of the energy value 50
3.6
Mineral analysis 50
3.7
Determination of physical
properties 51
3.8 Microbiological
examination 51
3.9
Sensory evaluation 51
3.10 Experimental
design 51
3.11
Statistical analysis 52
CHAPTER
4: RESULTS AND DISCUSSION
4.1 Pictorial
representation of bread and cookie samples
53
4.2 Functional
properties of wheat and soybean composite flour samples 55
4.3
Proximate composition of baked
(bread and cookie) samples 59
4.4 Mineral content of baked (bread and cookie) samples 69
4.5 Physical
properties of baked (bread and cookie) samples
75
4.5.1 Bread
samples 75
4.5.2 Cookie samples 78
4.6 Microbial quality of baked (bread and
cookie) samples 81
4.7 Sensory
properties of baked (bread and cookie) samples
84
CHAPTER
5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion
91
5.2 Recommendations 91
REFERENCES 93
LIST OF TABLES
Table 3.1:
Formulation of flour blends 39
Table 3.2: Recipe for production of bread 43
Table 3.3: Recipe for production of cookies 45
Table 4.1: Functional properties of wheat and soybean
composite flour samples 56
Table 4.2: Proximate
composition of bread samples 60
Table 4.3: Proximate
composition of cookie samples 61
Table 4.4: Mineral
content of bread samples 70
Table 4.5: Mineral
content of cookie samples 71
Table 4.6: Physical
properties of bread samples 76
Table 4.7: Physical
properties of cookie samples 79
Table 4.8: Microbial
quality of bread samples 82
Table 4.9: Microbial
quality of cookie samples 83
Table 4.10: Sensory
properties of bread samples 85
Table 4.11: Sensory
properties of cookie samples 86
LIST OF FIGURES
Figure 3.1: Flow chart for the production of
soybean flour 37
Figure 3.2: Flow
chart for the production of enriched bread
44
Figure 3.3: Flow
chart for the production of enriched cookies
46
LIST
OF PLATES
Plate 1: Pictures of soybeans and flour
samples 38
Plate 2: Pictures of produced bread
samples 53
Plate 3: Pictures of produced cookie samples 54
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF STUDY
Bakery
industry in Nigeria is considered as one of the major industries in food
processing. Bakery products are gaining popularity as processed foods because
of their availability, ready to eat convenience and reasonably good shelf life.
Wheat based baked products like bread, cookies, and cakes are popular among the
baked products and are
widely accepted and consumed throughout the world
(Olaoye and Onilude, 2008; Chavan et al.,
2016).
Bread,
according to Ndife et al. (2011) is a
fermented confectionary product produced mainly from wheat flour, water, yeast
and salt by a series of process involving mixing, kneading, proofing, shaping
and baking. It is a staple food in developing countries which is consumed in
large quantities because
it is an affordable excellent source of nutrients and is available in a “ready
to eat” form (Ezeocha and Onwuneme, 2016). Oluwafemi and Seidu (2017) noted
that bread is of high nutritional value, providing energy, iron, calcium,
vitamins and proteins.
Similarly,
cookies are convenient snacks product dried to a very low moisture content
taken among young people and adult to provide energy (Falola et al., 2011). 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). They are mostly eaten on a large scale
in developing countries where protein and caloric malnutrition are prevalent
(Akujobi, 2018). Cookies can be prepared in myriad shapes, flavors and textures,
and can be decorated (Akajiaku et al., 2018). It provides an excellent means of improving
the nutritional quantity of foods through incorporation of less expensive high
quality protein, minerals and vitamins, and has been employed in food product
enrichment (Okafor et al., 2002).
The
consumption of baked products is steady and increasing in Nigeria. It is
however, relatively expensive, being made from imported wheat that is not
cultivated in the tropics for climatic reasons. 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 (Talabi et al., 2019).
The need for strategic development and use of inexpensive local resources in
the production of popular foods such as baked products has been recognized by
organizations such as the Food and Agricultural Organization (FAO), the
International Institute for Tropical Agriculture (IITA), Nigeria and the
Federal Institute for Industrial Research, Oshodi (FIIRO), Nigeria (Falola et al., 2011).
Soybean
(Glycine max) is a legume belonging to the family leguminosae (Sanful and Darko, 2010). It is a remarkable source of
protein for both animals and human consumption and is also a leading source of
edible oils and fats (Alabi et al., 2001). Soybean
is an important source of proteins (40%), lipids (20%), minerals (5%), and B
vitamins for human nutrition (Lee et al.,
2007). Sanful and Darko (2010) reported that Soybean is the only
source that contains all the amino acids. It plays an
important role in infant nutrition. In particular, soy flour is used to fortify
traditional cereal-based foods (Aurelie et
al., 2017) and is generally acceptable when converted to flour from
which other forms of products are prepared (Famurewa and Folorunso, 2005).
Conversion of soybean to flour accompanied by different processing treatments
is necessary because some factors that make it unpalatable are eliminated; such
as the beany flavour, long processing time and difficulty in cooking the raw
bean (Famurewa and Raji, 2011). Apart from the higher nutritional content of
soybeans, it is also very cheap compared to wheat flour.
Research on the use of vegetable flours
as partial substitutes for wheat in the production of baked products has been
attributed to efforts being made at promoting cost effectiveness and
utilization of local crops as a result of huge foreign exchange that is
associated with wheat importation (Olaoye et
al., 2006). This has resulted in the need to source for locally available
and underutilized crops such as soybean in the production of flours to be used
as partial substitutes for wheat in bakery manufacturing. The inclusion of
soybean flour in wheat flour for bakery products will not only increase
varieties, but also improve the nutritional value of the products since soybean
have been reported to be nutrient dense legume.
1.2 STATEMENT OF PROBLEMS
The major source of flour for baked
products such as bread, cookies, cakes and chin-chin is wheat flour. Wheat
flour as the major ingredient for bakery products has dominated other potential
sources of flour for bakery products. However, the high cost of wheat flour has
led to a rise in the cost of bakery products in Nigeria and indeed other
countries in Sub-Sahara Africa (Ikpeme et
al., 2012). Also, the ban on importation of wheat into the country has
contributed immensely to the present high cost of bakery and confectionery
products. This has necessitated research efforts towards development of
composite flours involving partial substitution of wheat flour with those from
locally available vegetable crops in developing countries, especially Nigeria
(Olaoye and Ade-Omowaye, 2011).
1.3 JUSTIFICATION OF
STUDY
Some
studies have been carried out on the nutrient, anti-nutrient and toxic
substance composition of soybeans but there is limited information on the
utilization of soybean flour in production of baked products. The study would
therefore provide information on the nutrient composition of soybean flour as
well as the physical and chemical properties of baked products (bread and
cookies) formulated from it. This will help
increase the overall nutrient and baked products variety, reduce dependence on
wheat flour for production of baked products and also prevent nutritional
deficiency among the children. Also,
fortification of wheat flour with soybean flour could reduce post-harvest
losses of the seeds, create more market for the raw material and increase the
quest for production of nutritious food by food industries.
1.4
OBJECTIVES OF THE STUDY
The main objective of this study was
to evaluate the quality of baked products from flour blends of soybean and
wheat.
The
specific objectives of the study were:
1. To
produce composite flours from processed wheat and soybeans.
2. To
determine the functional properties of the flours.
3. To
produce bread and cookies with the composite flours.
4. To
evaluate the proximate, mineral and physical properties of the products.
5. To
evaluate the microbiological quality and sensory acceptability of the products.
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