EFFECT OF BROMATE ON THE SPECIFIC VOLUME OF BREAD ...

EFFECT OF BROMATE ON THE SPECIFIC VOLUME OF BREAD
MADE FROM SELECTED COMPOSITE FLOUR.
BY
JOLAOSHO AYOPEJU ELIZABETH
MATRIC NO: 05/0767
A PROJECT SUBMITTED TO THE DEPARTMENT OF FOOD SCIENCE
AND TECHNOLOGY, UNIVERSITY OF AGRICULTURE, ABEOKUTA.
IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE
AWARD OF BACHELOR OF SCIENCE.
UNIVERSITY OF AGRICULTURE, ABEOKUTA, OGUN STATE.
OCTOBER, 2010.

ABSTRACT
The study investigated the effect of bromate on the specific volume of bread baked from
cassava-wheat, maize-wheat, soy-wheat composite flour and wheat flour. The baking
temperature adopted for this investigation was 200 0 c and the levels of bromate used were 0,
30 ppm, 60 ppm which are equivalent to 0, 0.006 g and 0.012 g respectively.
The linear regression of the specific volume of bread samples which ranged from 1.28-2.08
cm 3 /g against bromate level showed that the specific volume decrease of cassava-wheat bread
samples at the different bromate level ranged from 1.97-1.68 cm 3 /g while for soy-wheat, samples
ranged from 1.59-1.28 cm 3 /g, however, there was increase in specific volume of maize-wheat
bread samples in the range of 1.61-1.73 cm 3 /g. Non-bromated wheat bread samples had an
average specific volume of 2.08 cm 3 /g.
Sample means (n=10) of bromated cassava-wheat bread at 60 ppm and bromated maize-wheat
bread at 30 ppm were not significantly different at p< 0.05. However, there was significant
different between sample means of other bread samples of the flour types at different bromate
level at p< 0.05.

DEDICATION
This project work is dedicated to Holy Spirit my mentor for his direction and to my husband, Mr.
Sanya Ogunjobi for his love which fulfills all laws.

AKCNOWLEDGEMENT
I am very grateful to God for his support, understanding and boundless love love he has
showered on me right from the cradle.
My gratitude also goes to my ever-competent and thorough supervisor, Dr. T.A. Shittu, for his
patience, understanding, encouragement and dedication in the development and execution of this
research work.
I am extremely grateful to my parents particularly my mother who sacrificed everything for her
daughters to get sound education and my father who supported me financially and materially in
the pursuit of my academic career.
To all my lecturers and staffs of the department of food science and technology, I say thank you
for the knowledge they have imparted on me.
Words cannot express my profound gratitude to Mr. Dapo Arowona of Honeywell Flour Mill
Limited for the opportunity I was given to make use of the company’s resources during my
research study.
To all my friends: Kemi, Deola, Doyin, Yinka girl, Titi, Dami, Tallest, Yinka boy, Chuks,
Osagie and my baby………… Dipo. I say thank you to all.
Finally, I am indebted to my loving, caring and dearest husband, Sanya Ogunjobi who believed
in me against all odds. I loved you, I love you and I will always love you.

TABLE OF CONTENT
Title Page
i
Certification
ii
Abstract
iii
Dedication
iv
Acknowledgement
v
Table of Content
vi
List of Tables
x
List of Figures
xi
CHAPTER ONE 1
1.0 Introduction 1
CHAPTER TWO 3
2.0 Literature Review 3
2.1 Bread 3
2.1.1 Functional Ingredient in Bread 4
2.1.1.1 Flour 4
2.1.1.2 Water 5

2.1.1.3 Yeast 5
2.1.1.4 Salt 5
2.1.1.5 Sugar 5
2.1.1.6 Shortening 6
2.1.1.7 Oxidizing Agent 6
2.2.0 Potassium Bromate 6
2.3.0 Gluten Protein 8
2.4.0 Composite Flour 10
2.4.1 Soya bean Flour 12
2.4.2 Maize Flour 13
2.4.3 Cassava Flour 13
2.5.0 Farinograph Analysis of Flour 14
2.6.0 Alveograph Test 15
2.7.0 Previous Research Work Conducted on Composite Flour 16
CHAPTER THREE 19
3.0 Materials and Method 19
3.1.0 Description of Project Environment 19

3.2.0 Material 19
3.2.1 Wheat Flour 19
3.2.2 Other Flour Substitute 19
3.2.3 Composite Flour Preparation 24
3.3.0 Methods 24
3.3.1 Chemical Composition 24
3.3.2 Functional Properties 24
3.3.2.1 Water Absorption Capacities 24
3.3.2.2 Oil Absorption Capacities 25
3.4.0 Farinograph and Alveograph Analysis 25
3.5.0 Experimental Design 25
3.6.0 Baking Experiment 27
3.7.0 Determination of Physical Parameters 29
3.7.1 Weight, Volume and Specific Volume Measurement 29
3.8.0 Statistical Analysis 29
CHAPTER FOUR 30
4.0 Result and Discussion 30

4.1.0 Chemical Composition of Composite Flours 30
4.2.0 Functional Properties of Flour used as Substitute for Wheat 32
4.3.0 Farinograph Analysis 34
4.4.0 Alveograph Analysis 36
4.5.0 Statistical Analysis of Result 38
CHAPTER FIVE 40
5.0 Conclusion and Recommendation 40
5.1.0 Conclusion 40
5.2.0 Recommendation 40
Reference 41

LIST OF TABLES
Table
Page
1. Formulation of Bread Making 26
2. Chemical Composition of Composite Flour 31
3. Functional Properties of Flour Substitute 33
4. Farinograph Data for the Composite Flours 35
5. Alveograph Data for the Composite Flours 37

LIST OF FIGURES
Figure
Page
1. Flow Chart for Wheat Flour Milling 20
2. Flow Chart for Cassava Flour Production 21
3. Flow Chart for Soy Flour Production 22
4. Flow Chart for Maize Flour Production 23
5. Flow Chart for the Production of Bread 28
6. Effect of Bromate on the Specific Volume of Bread Produced from Flour Samples 38

CHAPTER ONE
1.0 INTRODUCTION
Bread is one of the oldest, yet still most popular food in the world, invented by the Egyptians
some 800 years ago, bread launched as world conquering crusade during olden days of ancient
Greece and Roman Empire (Oyewole et al., 2002). The ever-growing popularity of bread may be
connected with its convenience, high acceptability, high energy content and low level of blood
cholesterol associated with its consumption (Gaman and Sherington, 1981). Water and flour are
the major components in a bread recipe. They affect the bread texture and crumb properties.
Potassium bromate is a flour improver that acts as a maturing agent. It acts principally in the late
dough stage giving strength to the dough during late proofing and early baking (KuroKawo et
al., 1990). Potassium bromated takes the form of white crystals or powder. Potassium bromate
has been used as a dough conditional for the past 60 years. According to USDA, it improves
dough processing properties, internal crumb quality and loaf volume in concentration from a few
to 75ppm, the highest concentration permitted by law. The mechanism by which bromate acts in
dough is complex and not well understood (DeStefanis, 1992).
In early 1990’s, the World Health Organization (WHO) discovered that potassium bromated if
consumed has the capacity to cause such diseases as cancer, kidney failure and several other
related diseases. The use of bromate has been banned in numerous countries. In Nigeria, the
bromated use in bread making was banned in 1993 (Obot et al., 2008).
Composite flours are mixture of flours from tubers rich in starch (e.g. cassava, yam, sweet
potato) and/or protein-rich flours (e.g. soy, peanut) and/or cereals (e.g. maize, rice, millet, buck
wheat), with or without wheat flour. Bread has become the second most widely consumed non-

indigenous food product after rice in Nigeria. Till date, most Nigerians have not been introduced
to other types of bread apart from 100% wheat flour. To cut the nation’s expenses on wheat
importation and find wider utilization for the increasingly produced cassava root the federal
government mandated the use of composite cassava-wheat flour for baking by adding a
minimum of 10% cassava flour to wheat for a start (Shittu et al., 2006). The inclusion of
composite flour into wheat up to 30% could still give an acceptable fresh loaf depending on the
source of flour (Defloor et al., 1993).
Although, the use of potassium is common to poorly wheatened bread, there is not much study to
find out whether similar dough improvement can be derived in composite bread. Adebambo
(2007) studied the effect of baking temperature and bromate on the oven development of
composite cassava-wheat bread by considering 3 factors (time, temperature and bromate level)
i.e. 40 minutes at 5 minute interval, 3 temperature range and 3 levels of bromate. The dough was
prepared in 2 batches, the first batch for non-bromated dough and the second batch for bromated
dough. The study suggested that the use of potassium bromate has a detrimental effect on the
oven development of bread made from composite cassava-wheat flour and the use of higher
baking temperature could reduce loaf size. However, the research work was inconclusive. It is
therefore important to validate this research work.
Therefore, the objective of this study was to validate the previous observation that inclusion of
bromate had negative effects on the loaf property of composite cassava-wheat bread. In addition,
other composite flour systems were also investigated to further establish the truthfulness of the
reported observation. It is hoped that the result of the study will assist in establishing commercial
feasibility of composite flour technology and probably advise bakers on the use of bromate on
composite bread.

CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 BREAD
Bread is a staple food prepared by cooking a dough of flour and water and possibly more
ingredients. Dough is usually baked, but in some cuisines breads are steamed, fried, or baked on
an unoiled skillet. It may be leavened or unleavened. Salt, fat and leavening agents such as yeast
and baking soda are common ingredients, though bread may contain other ingredients, such as
milk, egg, sugar, spice, fruit (such as raisins), vegetables (such as onion), nuts (such as walnuts)
or seeds (such as poppy seeds). Bread is one of the oldest prepared foods, dating back to the
Neolithic era, and is referred to colloquially as the "Staff of life". The development of leavened
bread can probably also be traced to prehistoric times.
Fresh bread is prized for its taste, aroma, quality and texture. Retaining its freshness is important
to keep it appetizing. Bread that has stiffened or dried past its prime is said to be stale. Modern
bread is sometimes wrapped in paper or plastic film, or stored in a container such as a breadbox
to reduce drying. Bread that is kept in warm, moist environments is prone to the growth of mold.
Bread kept at low temperatures, in a refrigerator for example, will develop mold growth more
slowly than bread kept at room temperature, but will turn stale quickly due to retro gradation.
The soft, inner part of bread is known to bakers and other culinary professionals as the crumb,
which is not to be confused with small bits of bread that often fall off, called crumbs. The outer
hard portion of bread is called the crust (Anonymous, 2010a).

2.1.1 FUNCTIONAL INGREDIENTS IN BREAD PRODUCTION
Quality control of your bread production should start with an understanding of what the
ingredients do. Using good technical skills, the baker can manipulate the inconsistencies of
ingredients to produce a uniform, consistent product. When discussing other ingredients, usage
levels are based in comparison to flour. This percentage is called the “Baker’s Percent.” When
using Baker’s Percent, the total flour will always add up to 100%
2.1.1.1 FLOUR
Flour comes from the wheat kernel and yields about 75% flour out of the wheat. White flour
comes from the middle of the kernel. Most formulations yield slightly over 1.5 pounds of bread
for every pound of flour.
Flour is divided into many separate parts. Most of the flour is composed of starch, and this starch
is either undamaged or damaged during the milling process. The damaged starch is fully
hydrated in the dough, but the undamaged (or native) starch cannot fully hydrate until the baking
process. Normal levels of damaged starch are between 6 and 11 percent in bread flours.
Along with fat, sugars and mineral content (ash), flour also has protein in it. This gluten-forming
protein is insoluble in water and forms a rubbery mass when mixed with water. Common
Specifications for flour include:
Moisture (12-14%)
Ash (.45 – .65%)
Protein (10.5 – 13%)

2.1.1.2 WATER
Water is the second main ingredient on the label, and the control of it is important. The main
function of water is hydration. All ingredients must have water to function. The total level of
water in bread dough is normally within the range of 55% to 65%. Water is the least expensive
ingredient in the formulation. However, too much water can dilute a good product.
2.1.1.3 YEAST
Yeast is used in bread dough to provide leavening. The level of usage in most bread is 2 to 5%
compressed yeast. Yeast converts fermentable sugars into carbon dioxide and alcohol in a
reaction called fermentation. Yeast is a living organism and its activity can be influenced by
storage practices. Dry yeasts have a longer shelf life and do not need to be refrigerated. Active
dry yeast must be pre hydrated in5 to 15 minutes before adding to dough in water.
Instant dry yeast can be added without pre hydrating. Compressed and cream yeasts need to be
stored at refrigerated conditions.
2.1.1.4 SALT
The main function of salt is to mask off flavors and bring out good flavor of the baked product.
Usage levels are normally between 1.5 and 2.5%. Salt also inhibits fermentation with a partial
dehydration of the yeast cell. Salt toughens the gluten and strengthens weaker flours.
2.1.1.5 SUGAR
Sugar provides food for the yeast. In a normal bread production process, 3 to 3.5 % fermentable
solids are required to sustain yeast activity. This food supply can come from added sugar, from

conversion of starches to sugars, or a combination of both. As residual sugar levels are higher,
crust color is darker, taste is sweeter, and moisture retention is improved.
The most common sugar is high fructose corn syrup (42% of the solids in the syrup are fructose).
When storing syrups, it is important to keep the temperature slightly warm (around 85 degrees
Fahrenheit). If the syrup gets cold, it will crystallize during storage. If it gets too hot, it will
darken or caramelize. Usage levels for sugars range from 0 to 15%.
2.1.1.6 SHORTENING
Shortening is used in bread production to provide overall lubrication. It is necessary to use a
small amount to facilitate slicing. It is recommended to use a minimum of .7 to 1% for good
slicing (although some bakers use less that this on low-calorie breads. Shortening also lubricates
the dough to ease dough expansion. It also tenderizes the crust and improves shelf life. Normal
usage levels are 0 to 5%. White pan bread usage between 1.5 and 3%. The most commonly used
shortening is soybean oil. Most bakers have removed all animal fate such as lard and butter from
formulations to that no cholesterol is on the label.
2.1.1.7 OXIDIZING AGENTS
Oxidizing agents are used by the baker to improve dough strength by creating bonds between the
protein chains. They will improve dough handling for better machining and contribute to
improved gas retention giving better volume and tighter grain to the finished product. Some
oxidants are fast acting, working in the mixer and early make-up stage, while ascorbic acid is late
acting, working in the proofer and early oven stage (Anonymous, 2010b).

2.2.0 POTASSIUM BROMATE
The major challenge in both the flour milling industries and bakeries is the baking quality of
flour, which is determined by the capacity of the dough prepared from it to retain gas. As a result
of world wide variation in the composition of flour, various treatments and supplements or
conditioning agents (flour/bread improvers) are added for strength during mixing, extensibility
for molding and also to increase loaf volume and texture.
Over the years, several improvers have been used but studies have shown some to be deleterious
to health, thereby necessitating the ban. The use of potassium bromate has been a common
choice among flour millers and bakers throughout the world because it is cheap and probably the
most efficient oxidizing agent. However, concern has been expressed on the harmful effects of
potassium bromated. Toxicological studies have convincingly shown that potassium bromated
affects the nutritional quality of bread by degrading vitamins A, B1, B2, E and niacin, the main
vitamins in bread. Also, studies have shown significant differences in essential fatty acid content
of flour treated with bromated or in bread made from such flour.
The British Food Manufacturing Industries Research Association reported in 1980 that
potassium bromate destroys folic acid in 10 days. It was reported by the International Chemical
Safety Cards (ICSC) that potassium bromated on inhalation can cause cough and sore throat in
human whereas on ingestion, it causes abdominal pain, diarrhea, nausea, vomiting, kidney
failure, hearing loss, as well as redness and pain both in eyes and skin.
Bromate has since been banned and removed from list of improvers generally regarded as safe
(GRAS) ingredients by the FAO/WHO Expert Committee on Food Additives worldwide since

1992. In Nigeria, use of potassium bromated in flour milling and baking has been banned by
NAFDAC since 1993.
Apart from potassium bromate, other improvers that are injurious to health include nitrogen
trichloride and ammonium persulphate. Nitrogen trichloride destroys the flour pigment and
reacts with methionine residue of the gluten protein forming methionine sulphoxine, which
causes brain disturbances in animal. Like most substances with chlorine as active ingredient, it
depletes the vitamin content of flour (vitamins A, E and B-complex). Ammonium Persulphite
has a depleting effect on the vitamin content of flour and causes skin allergy (Bakers Eczema).
2.3.0 GLUTEN PROTEIN
There is no way we can understand the action of potassium bromate on the gluten protein in
wheat without having a broad knowledge of the structure and composition of gluten. Gluten can
be defined as the rubbery mass that remains when wheat dough is washed to remove starch
granules and water-soluble constituents. Depending on the thoroughness of washing, the dry
solid contain 75–85% protein and 5–10% lipids; most of the remainder is starch and nonstarch
carbohydrates. In practice, the term ‘gluten’ refers to the proteins, because they play a key role in
determining the unique baking quality of wheat by conferring water absorption capacity,
cohesivity, viscosity and elasticity on dough. Gluten contains hundreds of protein components
which are present either as monomers or, linked by interchain disulphide bonds, as oligo- and
polymers (Wrigley and Bietz, 1988). They are unique in terms of their amino acid compositions,
which are characterized by high contents of glutamine and proline and by low contents of amino
acids with charged side groups. The molecular weights (MWs) of native proteins range from
around 30,000 to more than 10 million. Traditionally, gluten proteins have been divided into
roughly equal fractions according to their solubility in alcohol–water solutions of gluten (e.g.

60% ethanol): the soluble gliadins and the insoluble glutenins. Both fractions are important
contributors to the rheological properties of dough, but their functions are divergent. Hydrated
gliadins have little elasticity and are less cohesive than glutenins; they contribute mainly to the
viscosity and extensibility of the dough system. In contrast, hydrated glutenins are both cohesive
and elastic and are responsible for dough strength and elasticity. To simplify matters, gluten is a
‘two component glue’, in which gliadins can be understood as a ‘plasticizer’ or ‘solvent’ for
glutenins. A proper mixture of both fractions is essential to impart the viscoelastic properties of
dough and the quality of the end products. Though cysteine belongs to the minor amino acids of
gluten proteins (E2%), it is extremely important for the structure and functionality of gluten
(Grosch and Wieser, 1999). Most cysteines are present in an oxidized state and form either
intrachain disulphide bonds within a protein or interchain disulphide bonds between proteins.
These bonds are the main target for most redox reactions that occur during kernel maturation,
milling, dough preparation and baking. Additional covalent bonds formed during break making
are tyrosine–tyrosine crosslink between gluten proteins (Tilley et al., 2001) and tyrosine–
dehydroferulic acid cross links between gluten proteins and arabinoxylans (Piber and Koehler,
2005). The covalent structure of the gluten network is superimposed by non-covalent bonds
(hydrogen bonds, ionic bonds, hydrophobic bonds). Though this class of chemical bonds is less
energetic than covalent bonds, they are clearly implicated in gluten protein aggregation and
dough structure (Wieser et al., 2006). Evidence for the presence of hydrogen bonds in gluten
proteins are the dough weakening effect of hydrogen bond breaking agents (e.g. urea) and the
dough strengthening effect of heavy water compared with that of ordinary water. The importance
of ionic bonds can be demonstrated by the strengthening effect of NaCl or of bipolar ions such as
amino acids or dicarboxylic acids. Hydrophobic bonds contribute significantly to the
stabilization of gluten structure. They are different from other bonds, because their energy

increases with increasing temperature; this can provide additional stability during the baking
process (Wieser, 2006).
2.4.0 COMPOSITE FLOUR
In the 1960s and 1970s, composite flours very often found themselves at the focus of attention in
European and international cereal research. Most studies in this field were supported by FAO
(Food and Agricultre Organization of the United Nation. In two decades, bread consumption
increased continuously in many of the developing countries. There were three main reasons for
this:
A steady growing population;
Changes in eating habits;
An overall increase in income, which meant that a larger proportion of the income could
be spent on food.
In most cases the wheat or wheat flour needed for making bread, rolls and pastry goods had to be
imported, since the climatic conditions and soil did not permit wheat to be grown locally, or
made it very difficult. In these developing countries the imports of wheat had an increasingly
adverse effect on the balance of trade. For these reasons the FAO and these developing countries
were interested in the possibility of replacing the wheat needed for making baked goods, and also
pasta, wholly or partly with flour obtained from home-grown products. Possible sources were
tuberous plants rich in starch such as cassava, yam, sweet potatoes, protein-rich flour such as soy
and peanut and other cereals including maize, rice, millet and sorghum.

Although, it is well known that no other crops can achieve the baking properties of wheat,
composite flours became the subject of numerous studies. For the developing countries, the use
of composite flour had the following advantages:
A saving of hard currency;
Promotion of high-yielding, native plant species;
A better supply of protein for human nutrition;
Better overall use of domestic agriculture production
Composite flours are quite different from the ready-mixed flours familiar to miller and bakers.
Whereas ready-mixed flours contain all non-perishable constituent of the recipe for a certain
baked product, composite flour are only a mixture of different vegetable flours rich in starch or
protein, with or without wheat flour, for certain groups of bakery products.
The use of composite flour with or without wheat gives rise to technical problems in the
production of baked goods. From the baker’s point of view, the most important component of
wheat flour is the protein of the gluten, which plays a decisive role in dough formation, gas
retention and the structure of the crumb.
Most of the trials of composite flour have been carried out in Africa because of Africa’s
continually growing population. In the bread sector, the task was to produce typical French bread
with composite flour. The proportion of wheat flour in the different mixtures varied greatly, the
maximum being 70%. Because of the difficulty of keeping bread fresh, a great many experiment
were carried out with composite flour in biscuit production. So far there are no reports that bread
and biscuit have been produced from composite flour to any appreciable extent in an African
country. In spite of the lower price, the population is often disinclined to buy such bread because
of its unfamiliar flavor and its chewing properties, which differ from those of ordinary white

ead. Moreover, there are persistent rumors that many institutions profit financially from import
of wheat, and this would not be the case if locally-grown raw materials were used.
On 1 January 2005 Nigeria enacted a directive that makes the addition of 10% cassava flour to
wheat flour mandatory in order to support the local cassava crops and reduce exports of hard
currency. Unfortunately, cassava has already been a staple food for the very poor. Since the local
grower of cassava roots can by no means satisfy the theoretical demand of flour mills, at least a
temporary shortage with price increase is likely. Moreover, the available cassava flour qualities
differ greatly, for example in colour, taste and cyano-glycoside content. So it is still not certain
whether this initiative will soon result in the long-term use of cassava flour in wheat flour
(Anonymous, 2010c).
2.4.1 SOYA BEAN FLOUR
This finely ground flour is made from soybeans and, unlike many flours, is very high in protein
(twice that of wheat flour) and low in carbohydrates. Soy flour is ordinarily mixed with other
flours rather than being used alone. It has a wide variety of uses such as for baking and to bind
sauces. Soy flour can be defatted soybeans ground finely enough to pass through a 100-mesh or
smaller screen where special care was taken during desolventizing (not toasted) in order to
minimize denaturation of the protein to retain a high Protein Dispersibility Index (PDI), for uses
such as extruder cooking of textured vegetable protein. It is the starting material for production
of soy concentrate and soy protein isolate. Defatted soy flour is obtained from solvent extracted
flakes, and contains less than 1% oil. Full-fat soy flour is made from unextracted, dehulled
beans, and contains about 18% to 20% oil. Due to its high oil content a specialized Alpine Fine
Impact Mill must be used for grinding rather than the more common hammer mill. Low-fat soy

flour is made by adding back some oil to defatted soy flour. The lipid content varies according to
specifications, usually between 4.5% and 9%. High-fat soy flour can also be produced by adding
back soybean oil to defatted flour at the level of 15%. Lecithinated soy flour is made by adding
soybean lecithin to defatted, low-fat or high-fat soy flours to increase their dispersibility and
impart emulsifying properties. The lecithin content varies up to 15%.
2.4.2 MAIZE FLOUR
Maize flour is to Africans what wheat and potato flours are to Europeans and Americans. It is
harvested from the cub of the popular maize or corn plant, known botanically as Zea mays. It is
traditionally produced by pounding maize in a big mortar until a smooth powder is obtained.
Maize flour from the maize seed is now produced in very large scale by mechanization through
modern technology. Maize flour can be used exactly as wheat flour in making bread,
confectioneries, breakfast meals and more. Maize flour, also called corn flour is highly rich in
protein, dietary fibre and very low in fat. Maize or corn flour is by far the most widely eaten
flour after wheat and rice flour. It is uniquely rich in dietary fibre, protein, vitamin B6,
magnesium and omega 6 oils, vital for good heart, optimal bowel functions and fight against
infections. Fortified maize or corn flour has been used in the eradication of malnutrition in some
parts of the world.
2.4.3 CASSAVA FLOUR
Cassava flour is becoming a welcome ingredient in many food products, especially in Latin
American countries. In Africa, these potentials are still being explored especially in Nigeria
where technology for incorporation of 10% cassava flour in composite flour formulation has
proved successful. This development prompted the Federal Government to start working on the

legislation by the National Assembly of including cassava flour into composite flour formulation
starting from January 2005. It is projected that if Nigeria imported 3,390,000 MT of wheat/
wheat flour in 2003 chiefly for the bakery and related industry, then by January 2005, it is
expected that 339,000 MT of High Quality Unfermented Cassava Flour (HQUCF) will be
required by this sector of economy. Hence, opportunities thus exist for the investments of
HQUFC.
2.5.0 FARINOGRAPH ANALYSIS OF FLOUR
Farinograph determines the dough and gluten characteristics of flour by measuring the resistance
of the dough made from such flour against the mixing action of mixing blades. Farinograph test
is one of the most commonly used flour quality test in the world. The result are used as
parameters in the formulation to estimate the amount of water required to make a dough, to
predict the processing effect including mixing requirement for dough development, tolerance of
dough to over mixing and dough consistency during production. The results are also useful in
predicting finished product texture characteristics e.g. dough mixing properties are related to
firm texture.
Results obtainable from Farinogram include water absorption capacity, which this is the amount
of water required to center the farinograph curve on the 500-brabender unit (BU) line. It relates
to the amount of water needed for a flour to be optimally processed into end products. It is
expressed as a percentage.
Peak time: it indicates dough development time beginning from the moment water was added
until the dough reaches a maximum consistency before gluten strands begin to break. It is the
highest point on the curve and it is expressed in minute.

Arrival time: the time when the top of the curve touches the 500 BU- line. It indicates the rate of
hydration.
Departure time: this is the time when the top of the curve leaves the 500-BU line. It indicates the
time when the dough is beginning to break down
Mixing tolerance index: the difference in BU at the top of the curve at peak time and the value at
the top of the curve 5 minutes after peak.
Degree of softening: the difference in BU between line of the consistency and the medium line of
the torque curve 12 minutes after weakening begins (AACC, 2000).
2.6.0 ALVEOGRAPH ANALYSIS
Alveograph test was conducted on the composite flour in order to determine the dough
extensibility and resistance of the dough to deformation so as to have the knowledge of the
suitability of the flour for baking purpose. Alveograph is a measure of the amount of air bubble
dough can hold before it burst. It measures the dough strength and extensibility. It is represented
by the total area under the alveogram.
Generally, the higher the dough strength, the better the flour quality. The dough extensibility (L)
is a measure of the elastic property of the dough and its stability to enjoy pan flow. The height of
the alveogram (Pmax) tells us the ability of the dough to withstand pressure. The P/L
(extensibility ratio) is a very important factor than either P or L function. The lower the ratio, the
better the flour.

2.7.0 PREVIOUS RESEARCH WORK CONDUCTED ON COMPOSITE BREAD
Chi-Lin et al. (2004) conducted a research study on the quality and antioxidant property of bread
as affected by the incorporation of yam flour in the formulation. It was concluded that, bread
made with 5% of yam flour in the formulation did not show a significant difference in loaf
volume when compared with the control bread without yam flour. Bread made with 20% yam
flour substitution had a loaf volume that was reduced to 71% of bread without yam flour.
Moreover, the 25% substitution not only reduced the loaf volume to 54% but also resulted in
irregularly shaped bread. Loaf volume is one of the major quality indicators for bread and is
influenced by many factors including wheat flour compositions, additives and dough
fermentation conditions; regard to loaf volume, the highest ratio of yam flour to wheat flour in
the bread formulation should not exceed 20%. The effects of the ratio of yam flour : wheat flour
on the loaf height were similar to those effects on loaf volume. While 5% substitution showed no
significant difference, 25% substitution reduced loaf height to 62.8% of that shown by bread
without yam flour. As less wheat gluten in the formulation may retain less fermentation gas, this
may be the primarily reason for the decline in both loaf volume and height in bread containing
yam flour.
In 2007, Dimitrios et al. conducted a study on the effect of rice, soy and corn flour addition on
the characteristics of bread produced from different wheat cultivars. It was found that
supplementation of bread wheat flour with rice, corn, and soy flour up to 10% and durum wheat
flour up to 20% levels produced dough with satisfactory rheological properties and bread with
acceptable quality attributes (color, taste, and flavor). In contrast, as the level of inclusion
increases above 20% bread quality characteristics deteriorated proportionally, (low loaf volume,
lack of flavor, black specks, coarse crumb, hard texture) as a result of the replacement of gluten

y the added protein. The key factor in producing acceptable breads is gluten structure of the
flour, and this is the reason why the use of Greek durum wheat flour results in better bread
making potential and longer shelf life than bread wheat flour.
Olaoye et al. (2006) studied the quality characteristics of bread produced from composite wheat
plantain and soya bean. It was concluded that breads produced with soy flour substitution, up to
15%, were nutritionally superior to that of the whole wheat flour. Breads of good nutritional and
sensory qualities could be produced from up to 10% soy flour substitution in wheat flour. The
nutritional qualities and sensory attributes of plantain flour substituted breads are comparable to
that of the whole wheat. It is recommended that up to 15% plantain flour substitution could be
adopted in bread making processes, without affecting quality adversely. This will accrue in great
savings in the scarce resources of most developing countries, where wheat cultivation does not
thrive for climatic reasons.
Shfali et al. (2004) studied the effect of flour blending on the functional, baking and organoleptic
property of bread. It was discovered that substitution of wheat flour with soybean and barley
flour up to an amount equivalent to 10% of full-fat and defatted soy-flour, 15% for barley flour
resulted in significant reduction in loaf volume as the level of substitution with barley plus fullfat
soy and barley plus defatted soy flours increased. The highest reduction in loaf volume was in
bread made from wheat flour blended with full-fat soy flour at the 20% level. It could be that a
dilution effect on gluten with the addition of non-wheat flour to wheat flour and less retention of
CO 2 gas caused the depression in loaf volume. Another reason for the decrease in loaf volume
could be the presence of relatively high concentrations of low molecular weight thiols, especially
reduced glutathione, which activates proteolytic enzymes, thereby causing a detrimental effect
on loaf volume.

In 2007, Adebambo studied the effect of baking temperature and bromate on the oven
development of composite cassava-wheat bread, this he did by using the straight dough method
for the dough preparation. The experimental design was such that, he used three level of bromate
and while varying the baking temperature for baking bread with different bromate level. He
concluded that the use of potassium bromate has a detrimental effect on the composite cassavawheat
bread development and the use of higher baking temperature could reduce loaf size.

CHAPTER THREE
3.0 MATERIALS AND METHOD
3.1.0 DESCRIPTION OF PROJECT ENVIRONMENT
The project work was carried out at the Research and Development laboratory of Honeywell
Flour Mill Limited, 2 nd gate Tin-Can Island, Apapa, Lagos state, Nigeria. The average ambient
temperature and relative humidity of the baking room was 32 o C and 56% respectively.
3.2.0 MATERIALS
3.2.1 WHEAT FLOUR
Honeywell Superfine flour was used for the project work. The flour was from the production
line. The procedure for obtaining the flour is summarized as thus in Figure 1.
3.2.2 OTHER FLOUR SUBSTITUTE
Cassava flour, Maize flour and Soy flour were self manufactured. Cassava root was purchased at
UNAAB farm and was processed within 24 hours after harvest. Soya bean and maize grain was
purchased from Lafenwa market, Abeokuta, Ogun State. The flow charts for their production are
respectively shown below in Figures 2, 3 and 4.

FIGURE 1:
FLOW CHART FOR WHEAT FLOUR MILLING

FIGURE 2: FLOW CHART FOR CASSAVA FLOUR PRODUCTION

FIGURE 3: FLOW CHART FOR SOY FLOUR PRODUCTION

FIGURE 4: FLOW CHART FOR MAIZE FLOUR PRODUCTION

3.2.3 COMPOSITE FLOUR PREPARATION
Composite flour was made by mixing 10 parts of cassava flour or soy flour or maize flour and 90
parts of wheat flour as approved by the Federal Government of Nigeria in November, 2004.
Other materials include granulated sugar, yeast and baking fat (Shittu et al., 2006).
3.3.0 METHODS
3.3.1 CHEMICAL COMPOSITION
Some proximate analysis including moisture, ash content and protein were conducted on the
composite flour samples. This analysis was conducted at Honeywell Flour Mill Limited, 2 nd gate
Tin-Can Island, Apapa, Lagos state, Nigeria.
3.3.2 FUNCTIONAL PROPERTIES
Some functional properties of the flour to be used were determined, namely: water absorption
capacity and oil absorption capacity of soya bean flour, maize flour and cassava flour.
3.3.2.1 Water Absorption Capacities
Water absorption of flours was measured according to the centrifugation method of Anderson et
al. (1969). 1.0 g of the sample was weighted in a centrifuge tube and 10 ml of water is was added
and mixed thoroughly. The dispersions were allowed to stand for 30 min, followed by
centrifugation for 15 min at 3000 rpm. The supernatant was decanted the sample was reweighed.
The amount of water retained in the sample recorded as weight gained. The water absorption
capacity (WAC) was calculated:
Weight of water absorbed
WAC (g/g)
Sample weight

3.3.2.2 Oil Absorption Capacities
Oil absorption was also determined using the method of Anderson et al. (1969). 1 g samples
were mixed with 6 ml of corn oil in pre-weighed centrifuge tubes. The content was stirred for 1
min with a thin brass wire to disperse the sample evenly in the oil. After a holding period of 30
min, the tubes were centrifuged for 25 min at 3000 rpm. The separated oil was removed with a
pipette and the tubes were inverted for 25 min to drain the oil prior to reweighing. Oil absorption
capacities (OAC) were expressed as weight of water or oil bound per weight of the sample on a
dry basis.
Weight of oil absorbed
OAC (g/g)
Sample weight
3.4.0 FARINOGRAPH ANALYSIS AND ALVEOGRAPH ANALYSIS
Farinograph and alveograph analysis was conducted on the 3 composite flour samples. This was
done at Honeywell flour mill limited, 2 nd gate Tin-Can Island, Apapa, Lagos state, Nigeria.
3.5.0 EXPERIMENTAL DESIGN
The experimental design will consider two factors (flour type and bromate level) i.e. 3 types of
flour and 3 levels of bromate each level of bromate with 10 replication of data point giving a
total of 100 samples.

Table 1: Formulation of bread making
Ingredients Percentage (%) Quantity (g)
Flour 100 2000
Salt 2 40
Yeast 0.75 15
Sugar 10 200
Butter 5 100
*Bromate
0-60 ppm
% Values are based on the total flour weight (2000g)
* Concentration based on flour weight

3.6.0 BAKING EXPERIMENT
The ingredient was dry mixed using a spiral mixer (D100NA, Dierus and Sohne, Germany) and
later water was mixed with the initial dry mix until soft dough that can easily be handled is
produced. Mixing was done at low speed for 2 min and high speed for 8 min totaling 10 min
mixing time. The amount of water was added was determined from the water absorption in
Farinograph analysis. Kneading was done manually and the whole mass was divided into small
sizes and weighed into 320 g each by means of balance (0.1 g accuracy) and molded to desired
shape. The dough was set in baking pans, it was then transferred to a electric proofing machine
(D23-N11, Dierus and Sohne, Germany) where proofing of the dough was done for 3 hours at
32 o c. This was further facilitated by filling the ground tray with warm water. The proved dough
was baked in a temperature controlled deck oven (P1CCOLO-1, Genway, Germany) at 180 o C
over a period of 30 min. The baked bread was allowed to cool prior to analysis. The flow chart
for bread production is shown in Figure 5.

FIGURE 5:
FLOW CHART FOR THE PRODUCTION OF BREAD

3.7.0 DETERMINATION OF PHYSICAL PARAMETERS
3.7.1 WEIGHT, VOLUME AND SPECIFIC VOLUME MEASUREMENT
The weight of the baked bread was determined using a digital scale of 0.1 accuracy. The volume
was determined with the aid of bread volume measurer (BVM 370-LC). The bread volume
measurer uses a laser technology to determine the volume. A laser sensor moves in a half circle
around the rotating product. The length/height, width and depth are measured and the volume is
calculated by a specially devised computer program. Instead of just assessing the volume, which
is the best description of the seed displacement method, the BVM will determine the correct
volume. The specific volume was calculated as:
Specific volume
Loaf volume (cm
Loaf weight (g)
3
)
3.8.0 STATISTICAL ANALYSIS
Linear regression of the values of specific volume against baking was carried out using
Microsoft Excel 2007 and SPSS version 15.

CHAPTER FOUR
4.0 RESULT AND DISCUSSION
4.1.0 CHEMICAL COMPOSITION OF COMPOSITE FLOUR
The results of some chemical composition tested for each flour type are stated in Table 1. The
moisture, ash and protein contents of the composite flour ranged from 13.0-13.3%, 0.82-0.88%
and 9.95-12.7%, respectively. The higher protein content in soy-wheat composite flour might be
due to higher protein in soy flour than other substituent flours.

Table 2: Chemical composition of the composite flours
FLOUR TYPE
MOISTURE ASH PROTEIN
(%)
(%)
(%)
SOY-WHEAT 13 0.88 12.7
MAIZE-WHEAT 13.3 0.82 10.45
CASSAVA-WHEAT 13.1 0.86 9.95

4.2.0 FUNCTIONAL PROPERTIES OF FLOURS USED AS SUBSTITUTES FOR
WHEAT
The results of the functional properties of cassava, soy and maize flour tested for are stated in the
table 2. The water absorption capacities and oil absorption capacities ranged from 1.65-2.24 g/g
and 0.98-1.36 g/g respectively. There is a negative correlation between the water absorption
capacity of flours used as substitute for wheat and the water absorptivity of their respective
composite flours. i.e. soy flour had the highest water absorption capacity followed by cassava
flour and then maize flour, however, the water absorptivity of soy-wheat flour was the lowest
followed by maize-wheat and cassava wheat.

Table 3: Functional properties of the flours substitute
FLOUR
WAC
(g/g)
OAC
(g/g)
CASSAVA 1.76 1.36
SOY 2.24 1.09
MAIZE 1.65 0.98

4.3.0 FARINOGRAPH ANALYSIS
The farinograph data for wheat and the three composite flours are stated table 6. The water
absorption, dough stability, mixing tolerance index and degree of softening ranged from 56.9-
60.4 %, 8-20.5 min, 20-70 BU and 60-80 BU, respectively. Cassava-wheat flour had the highest
water absorptivity followed by maize-wheat then soy-wheat. There was high correlation between
dough stability and the protein content of the flour. Soy-wheat had the highest degree of
softening, followed by cassava-wheat flour, then maize-wheat flour. All flour types had the same
development time.

Table 4: Farinograph data for the composite flours
QUALITY INDEX
FLOUR TYPE
Wheat Soy-Wheat Maize-Wheat Cassava-Wheat
WATER ABSORPTION (%) 58.3 56.9 59.0 60.4
DEVELOPMENT TIME (min) 2 2 2 2
DOUGH STABILITY (min) 10 20.5 10 8
MIXING TOLERANCE INDEX (BU) 30 20 30 70
DEGREE OF SOFTENING (BU) 80 80 60 75

4.4.0 ALVEOGRAPH TEST
The alveograph data for wheat and the three composite flours are stated in table 7. The
extensibility ratio and gluten factor ranged from 1.05-2.76 and 15.7-20.8 respectively. The
extensibility ratio of each flour samples compared to wheat was higher and but the higher the
extensibility ratio, the poorer the flour quality hence, the composite flours are of low quality
when compared with wheat flour. However, the value of extensibility ratio of maize-wheat flour
tends to be closer to that of wheat flour. The gluten factor of the composite flour was lower
compared to the value of gluten factor of wheat flour. The value was the same for maize-wheat
and cassava-wheat flour while it was lowest in soy-wheat flour.

Table 5: Alveograph data for the composite flours
QUALITY INDEX
FLOUR TYPE
Wheat Soy-Wheat Maize-Wheat Cassava-Wheat
DOUGH STRENGTH (kJ) 47.4 48.5 38.9 48.6
WORK DONE (kJ) 310 317 255 318
PRESSURE (mm H 2 O) 91 138 95 122
EXTENSIBILITY (mm) 87 50 60 60
EXTENSIBILITY RATIO 1.05 2.76 1.58 2.76
GLUTEN FACTOR 20.8 15.7 17.2 17.2

4.5.0 STATISTICAL ANALYSIS OF RESULT
Figure 6 : Effect of bromate concentration on the specific volume of the composite bread
samples. Sample means (n=10) followed by the same alphabet are not significantly different
at P

The effect of different level of bromate on specific volume is shown in Figure 1, from where it is
evident the as the level of bromate increases as the specific volume decreases for cassava-wheat
and soy-wheat bread while for maize-wheat the specific volume marginally increases as the level
of bromate increases. However, the specific volume was highest in pure wheat non bromated
bread sample. Soy-wheat bread did not compare with the other composite bread; it was the
poorest in terms of specific volume when compared with maize-wheat and cassava-wheat bread.
Maize-wheat composite bread showed similar trend with wheat bread if bromate were to be used
in baking wheat flour in that unlike cassava-wheat and soy-wheat flour, the specific volume of
bread produced from maize-wheat flour has a positive relationship with bromate level. This
observation in bread baked from maize-wheat flour can be explained based on the fact that maize
and wheat belong to the same family (cereal family) thus there is resemblance in their starch
chemistry and dough behavior of their flours, the only difference between these grains lies in
their gluten content. Cassava belongs to root and tuber family while soya bean belongs to the
legume family, there is definitely variability in their starch system apart from gluten content
when compared to that of wheat flour.
From the statistical analysis, potassium bromate had the same effect on the specific volume of
bread baked from cassava-wheat flour at 60 ppm bromate level and maize-wheat flour at 30 ppm
bromate level at p

CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
5.1.0 CONCLUSION
It can be concluded that the use of potassium bromate has a detrimental effect on the loaf volume
of cassava-wheat and soy-wheat bread in that it causes reduction in the specific volume of the
bread which decreases as the bromate level increases. However, the use of bromate on maizewheat
flour increases the specific volume of bread made from this flour.
5.2.0 RECOMMENDATION
It is recommended that government should ensure effective implementation of inclusion of 10%
cassava-wheat flour into wheat formulation by flour manufacturers so as to improve the
commercial feasibility of composite cassava-wheat flour. In doing this, bakers who remain
adamant in using potassium bromate as bread improver despite its ban in Nigeria will be forced
to respect this government policy because the use of bromate in composite cassava-wheat bread
does not work as an improver; rather it reduces the loaf volume.

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