CEREAL TECHNOLOGY

CEREALS OF ECONOMIC IMPORTANCE IN KENYA

Kenya produces much kind of cereals such as wheat, maize, sorghum, and millet
Maize and wheat are the most common and are produced in large quantities
The two cereals are prepared in many different ways
Maize is a staple in many communities in Kenya it can be eaten off the cob
When it’s dry it can be mixed with other ingredients to make a meal
It can also be ground into flour and used in many ways
Wheat is mainly ground into flour and prepared into different products
MAIZE MILLING
Variety structures and composition of maize
There are different types of maize (referred to as corn in some communities) cultivated around
the world
The most common are dent corn, flint corn, and pop corn
Each of these are used in different ways; dent and flint corns usually have hard endosperm and a
depression at the top especially when dry
The two are dry and are used as a staple food e.g. ugali or eaten whole
They are also used in the starch industry for making laundry starch
Sweet corn is thin yellowish in color. It has a higher sugar content hence taste sweet
It has small seeds and is suitable for canning when mixed with other ingredients such as peas and
carrots
Structure of maize
The maize grain consists of the following parts;
Tip-1%
Hull-5%
Germ-12%
Soft endosperm and hard endosperm- 82%
The maize contains the nutrients in different parts;

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 starch Protein fats fiber

Endosperm 95.1% 75.3% 12.9% 12.5%

Germ 4.7% 22.6% 85.8% 29.3%

hull 0.2% 2.1% 1.3% 51.2%

MAIZE MILLING
They are two methods;
✔ Wet milling
✔ Dry milling

Wet milling
This is a method that is mainly used in the production of starch
Maize is first soaked with Sulphur dioxide solution to soften and loosen the hull
The maize is then taken to the milling machine which contains the rows and screens for
separating the endosperm from the germ and the hull. After this the endosperm is completely
ground into flour
Dry milling
It is of two types;
● Degerming system
● Non degerming

Both produce maize flour but of different types because in the nondegerming system the whole
maize garin is ground and the flour produced doesn’t have a long shelf life. This is because the
germ oil rapidly develops rancidity
Degerming system
Cleaning and separating
This is the removal of any contaminating material from the maize such as the maize seeds other
mixed cereals, dirt, chuff, small stones and metals
The milling machine usually has screening sieves that help in the removal of small contaminants
Also has a magnetic separator to remove the metals
Tempering
This is a process that helps in the removal of the hull and the germ

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It also involves the introduction of the correct moisture content and temperature and time to
loosen the hull and the germ making them easy to remove e.g. maize tempering can be done in
three ways;
i. 20.5 moisture content. This is done at a temp of 27-32oC for 65 minutes
ii. The moisture content s raised to 22% at 38oC for 75 minutes
iii. Moisture is raised to 24% AT 33oC for 45 minutes
Removal of the tip, the hull and the germ
Drying
The maize is dehydrated to a moisture content of 12-13333% to facilitate milling
Reduction
Involves reducing the maize into flour using iron rolls in milling machines
Grading is also done tom categorize the flour of different qualities
WHEAT MILLING
Classification
There are many different varieties of wheat in the world today
The main differences in varieties are brought about by different color of grain, hardness of the
kernel
Kernel
Wheat is also classified by botanical species of which the two main species of wheat are;
✔ Triticum durum
✔ Triticum compactum

The two main classes of wheat are dependent on the hardness of the kernel. They are;
a. Glassy wheat
b. Chalky wheat
Glassy wheat
It is further classified into;
i. Hard- strong flour (used for bread baking)
Durum flour for pasta products
ii. Semi strong flour- used for bread making
Chalky wheat
It is soft flour and divided into two;

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 a. Pastry flour- for cakes and biscuits
b. Weak flour- for nodules
STRUCTURE AND COMPOSITION OF THE WHEAT FLOUR
It consists of three main parts;
i Germ(embryo)
ii Endosperm
iii Bran(outer covering)
The bran is thee protective covering of the grain and consists of several distinct layers
The germ or embryo lies in the base of the grain
The germ is rich in fats and vitamin E
The brane is rich in the B complex vitamins
The endosperm is the largest part of the kernel and it’s in carbohydrates and proteins
BLANK SPACE
WHEAT MILLING
There are two main aims of milling wheat;
⮚ To separate as completely as possible the bran and the germ from the endosperm
⮚ To reduce the maximum amount of endosperm to flour i.e. obtain maximum extraction
from flour from the wheat
THE MILLING PROCESS
Separating and cleaning
The wheat contains a small amount of contaminating materials of weed seeds, other cereals, dirt,
small stones and metals
● The miller uses the following equipment in the process;
● The milling separator
● Magnetic separator
● Screening machines
● Sieves

Blending
Wheat has so many uses such as bread, cake, pasta e.t.c
The quality of flour depends on the variety of wheat , soil or climatic conditions
Depending on the use of the flour different varieties of wheat must be blended to achieve this

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Tempering and conditioning
The bran of the kernel is tougher than the germ and the endosperm
The toughness of the bran increases with decrease in moisture content
The germ contains oil and therefore with the weight amount of moisture it is easily flattened by
the rolls and removed
The endosperm on the other hand softens with the increase in moisture. For this reason,
tempering and condition preparing prepare the wheat kernel foe separation and milling
Conditions for tempering
The wheat on reception at the industry has an average moisture content of 7-10%
To temper and condition add wheat, a moisture content of 19% should be achievedu the bran and
germ are easily separated from the endosperm
Break~w system
This consists of the break rolls and the sifters
The tempered wheat is carried through a series of grinding operations
It consists of a system of 3-6 sets of corrugated iron rolls revolve in opposite directions and at
different speeds
In this stage the endosperm is separated from the bran and the germ
This system yields 5 products according to the size;
a. The coarsest fragment (germ and bran)
b. The medium fragment (middling)
c. Finest material (break flour)
The medium size particles are known as middling and consist mainly of endosperm and are
carried on the next step of purification
The finest materials is usually the best flour and is called the break flour

Purification
The middlings are composed mainly of endosperm but with small amount of bran and germ.
The bran and germ in the middlings are removed using a sifter specifically known as a purifier

Reduction system

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After purification the middlings are further reduced with smooth rolls which are also referred
to as reduction rolls
The system consist of a set of smooth rolls and sifters
This system has two main products;
● Middling flour
● Gray short- which is coarse endosperm fragment and any remaining bran and germ

Gray short is usually used for manufacture of animal feed

THE NATURE OF WHEAT FLOUR
Wheat protein
At least 80% of wheat protein is found in the endosperm
The two main proteins found in wheat are gliadin and glutenin
These proteins are important in bread making because when they combine with water they
produce gluten
The gluten has the characteristic of elasticity and gase retention
Carbohydrates
The main carbohydrates are starch, dextrin, cellulose and free sugars
The starch in wheat flour consists of two types of particles;
i Normal particles
ii Damaged particles
The damaged particles of starch granules occur as a result of pressure during grinding
In bread making the damaged starch granules are more important and they play the following
roles;
a. They are able to form more sufficient fermentable carbohydrates
b. The damaged starch is easily attracted to 2 and B-amylase enzymes that are naturally
found in wheat flour. The starch on attack by the enzymes changes to maltose which is
then broken down to carbon dioxide and alcohol by enzyme maltose and zymase
found yeast
c. Damaged starch easily absorb water making mixing time shorter
d. The damaged starch produces dextrin which gives taste to the final product
Lipids
The lipids in wheat occur in amount of 2% in the flour
The lipids in wheat are of two types;

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 ✔ Phospholipids
✔ Free lipids

The phospholipid reacts with the proteins in the flour during dough making to form a
lipoprotein system which increases the gas retention power of the dough
However, wheat lipids are prone to rancidity (spoilage by oxidation) therefore millers make
an effort remove an the lipids during milling
Minerals
They are also referred to as ash content
The quantity of ash in wheat depend on the type of soil and rainfall among other climatic
conditions
Ash content in one way influences the flavor of the products and calcium specifically
influences the quality of water used in bread making hence influencing fermentation
Enzymes
Wheat flour naturally contains several types of enzymes; 2 and B-amylase, protease, lipase,
lip oxidase and dehydrogenase
The 2 and B-amylase are important for improving bread flour properties
2 amylase and protease are sometimes sufficient and need to be added artificially
INGREDIENTS IN BREAD MAKING
Yeast
The yeast used in bread making is saccharomyces cerevisiae
There are three types of yeast namely; compressed yeast, bulk yeast and active dry yeast
The active dry yeast is the common one in bread making
This is because it keeps its activity at room temperature for a long time. When it is in a dry
state, the active dry is dormant; it therefore requires free fermentation in warm water for
about 15 minutes before use
The structure of yeast cell

Yeast works in different ways during bread making i.e.

● Fermentation
● Respiration

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In fermentation there is production of CO2 and alcohol and a little energy
In respiration there is production of some CO2 but mainly production of energy used mainly
during fermentation
The rate and power of fermentation depends on the pH value and the temperature of the
dough
The optimum pH value for the yeast is 4.7 (acidic)
The optimum temperature for yeast activity is 38oC. if the temperature is too low there is
reduced yeast activity hence reduced fermentation
Yeast food and dough conditions
There are two types of yeast foods;
● Organic yeast food
● Inorganic yeast foods

The organic is mainly the enzymes that’s not sufficient naturally in it e.g. 2-amylase and
protease
When protease is sufficient it makes mixing time, fermentation time and final proofing time
short
Excessive protease on the other hand is completely disintegrate and the dough loses it
capacity for gas retention
Inorganic yeast food is chemically produced and artificially introduced during bread making
to serve the same purposes as the organic yeast foods
NOTE: Both of them provides nutrients to the yeast and oxidants and improves for the dough
The functions of yeast foods are as follows;
i To supply oxygen as an important nutrient to the yeast
ii To decrease the ph value of the dough
iii To provide oxidants to the dough. Oxidants strengthen the gluten hence helping in its
development
iv To improve the quality of water. This is by addition of Ca2+ ions which adjust the
hardness of water. Hard water toughens the gluten while soft water makes the dough
very soft and sticky
Salt
Performs three main functions in bread making;
i To improve the flavor of products
ii Salt controls fermentation. Salt prevents the dough from fermenting at erratic rate
(controlled CO2 is produced)

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 iii To strengthen the gluten hence proper development
Water
Is one of the key ingredients in bread making without which there will be no dough formation
E see the gluten. This retards fermentation because there is no web like structure to retain the
gas formed
i Soft water makes the gluten very soft and unable to hold the web like structure. It also
produces a sticky dough
ii Alkaline water reduces the fermentation rate because the optimum pH level for
fermentation is 4.7 which is acidic
NOTE: The quality of water is collected by adding calcium ions which are found in bread
improvers. Bread improvers also collect the pH value
Sweetening agent
There are many materials that can be used as sweetening agents in bread making
Sugar is the typical sweetening agent but others such as syrup, inverted sugar, glucose, honey
etc. can be used
Syrup and inverted sugar have become more common because they are sweeter than common
sugar and cheaper
Functions of sweeteners
✔ To give flavor and coloring materials. The mailand reactions and caramelization gives
color and flavor
In mailand reaction there is a reaction between a reducing sugar (carbohydrate) and amino
acids
Caramelization
Sweeteners caramelize an exposure to very high temperatures. At about 190oC the sugar syrup
changes to brown
At a much high temperature the sugar changes to black
✔ To provide nutrients (sugar is carbohydrate in nature hence energy giving)
✔ Sugar regulates fermentation. Sugar plays a role as a yeast food. It provides the energy
for the yeast to grow. The higher the sugar the faster the rate of fermentation.
However, sugar should not exceed 15% of the flour weight
Above 15% sugar destroys the yeast cells by dehydrating them through osmotic pressure
✔ Sugar softens baked products 8 gluten development

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Very soft or fluid oil breaks developed gluten chains resulting in a soft dough that does not
retain gase
In the past lard (fat from pork) was commonly used in bread making because it had the
desired characteristic i.e. it was neither hard nor fluid
Marine oil can’t be used in bread baking because it was too fluid
Beef and mutton fats could not be used because they were too hard
Today animal and vegetable oils have been treated by a method called hydrogenation to
achieve a desired characteristic i.e. not too hard or too fluidly
Because of this treatment these products are referred to as shortening
Functions of fats
1. To give gluten its desired characteristic
2. To give tenderness to bread
3. To improve keeping quality
4. To improve nutritive value
5. To give flavor to the products
6. Stabilize cake butter
7. Help a dough become big in the oven
8. To give shortness and crispness to biscuits
Milk
Available sorts of milk are chiefly fresh and dry (skimmed) milk
Composition of fresh and skimmed

moisture protein fat Lactose ash

Fresh milk 87.5% 3.4% 3.65% 4.75% 0.7%

Skimmed 3.0% 35.5% 0.8% 52.8% 7.9%

milk

Functions of milk
i To increase the nutritive value
ii To help the buffer action (normally the pH within the dough
iii Milk retards the fermentation rate because the pH 4.7 is the optimum pH for enzymes
action
iv To help color and flavor formation; milk contains lactose which is not attacked by
yeast. As lactose is also reducing sugar. It is used for maillard reactions as well as

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 caremalization. When the skimmed milk powder is used it has to be prevented from
touching water directly. The powder form lump with water easily

pH on mixing pH after fermentation for

45 minutes

Milk free dough 5.8 5.1

Milk containing dough 5.94 5.7

Emulsifiers
There are two types of emulsifiers;
✔ Natural
✔ Artificial

An emulsifier has at least on hydrophilic radical and one hydrophobic radical

Functions of emulsifiers
i To retard the retro gradation of starch (see the keeping quality)
ii To increase the volume of bread; the capacity of retention gas become strong
iii To make tender crust, finer grain and smoother texture
Eggs
There are for types of egg products;
✔ Shell eggs
✔ Liquid eggs
✔ Frozen eggs
✔ Dried- moisture has been removed for packaging purpose

Egg is composed mainly of the translucent egg white and yellow yolk
Chemical composition of an egg

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 moisture protein fat CHOs Ash

Whole egg 72.5% 13.4% 11.5% 1.5% 1.1%

Yolk 49.0% 16.7% 31.6% 1.2% 1.5%

white 86.6% 11.6% 0.2% 0.8% 0.8%

The quality of shell egg has to be checked before use. Available methods are; candling and
specific gravity method
The candling method involves holding an egg before a bright light in a dark room and then
looks through the shell. In case of a good egg the yolk moves slightly away from the center
While in case of a bad egg the yolk moves more quickly and floats closer to the shell
The specific gravity of an egg is usually 1.08 to 1.09 (fresh egg)
A very old or bad egg is under 1.02. This being hints and the older the egg the bigger the size
of the air cell
The egg has a lot of pores on the shell surface. The pores of a new laid egg are covered with
the article layer which prevents microorganisms from invading the egg
NB: If you want to keep the eggs for a long time you should not wash the surface of the eggs
water

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Functions of egg
i To give nutritive value and flavor
ii To increase the volume of cakes; this role results from the whipping properties of
white eggs
iii To give good grain, good texture to cake; egg has a property of emulsification because
they all include lecithin
iv To give good color
Dough preparation
Mixers
There are two types of mixers;
✔ Horizontal
✔ Vertical

Horizontal mixers- it's a large capacity mixture of between 45-900kg. It's used in large
companies for mass production
Vertical mixers- it's a small capacity mixer of between 5-20kg
It is convenient for small bakeries or the smaller ones for home use
The vertical mixer has several fittings depending on purpose it has a whisk or whipper and
beater
The whipper and beater are used for butters while the hook is mainly for the dough
These fittings are also called mixer arms
The main purpose is to blend the flour and water with other ingredients and also to mix,
compress, fold and push the blended mash
In bread making the blended mass become elastic and cohesive into a mass called a dough
In bread making therefore the functions of mixers are;
i To form a homogeneous mixture of all the ingredients
ii To physically help the gluten to be formed. Gluten is formed by the physical action
into a web like structure
iii To produce the desired characteristic of gluten i.e. stretch ability or elasticity and
viscosity
Well-developed dough has the following qualities;
✔ The surface has a smooth appearance
✔ When stretched using finger produces a thin translucent membrane
✔ Has optimum or greatest elasticity

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7
STAGES OF DOUGH DEVELOPMENT
Initial stage
This stage involves the incorporation of the dough ingredients. The mas formed at this stage
is slack (weak), wet and sticky
Gluten has not formed but its formation starts
Clean up stage
In this stage hydration of all ingredients has finished and dough formation has started
The dough gains more elasticity and the walls of the mixer bowl are left clean
Development (final stage)
This is a very critical stage. The dough has the strongest elasticity and cohesion (complete
mixing)
When stretched, the dough produces a semitransparent or translucent membrane
The surface is also a smooth
The dough is in its best condition for baking
Let down stage
When the developed dough is continuously mixed for long it begins to lose its elasticity and
become highly extensible
Break down stage
The gluten structure is completely disintegrated
The dough goes back to a slack non elastic mass
It produces products that do not have any volume and have very poor texture
Mixing time
Actual dough mixing time depends on various factors such as the quality of the flour and
other ingredients such as salt, water quality and pH
Other factors are mixing speed, the temperature of the dough, points of salt addition etc.
Explain factors that influence mixing time
Element factor degree effects of mixing time

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1. Quality of flour
✔ Quality of protein more of quantity protein longer
✔ Quality of protein stronger longer the mixing time
✔ Amount of maltose more longer
2. Mixing speed low longer
3. Temperature higher shorter
4. pH value lower shorter
5. Quality of water distilled water very long
There are several methods of dough mixing; the straight dough method, sponge dough
method and liquid fermentation brew
Straight dough method
It's a single step method
All ingredients mixed together at the same time except shortening
The dough temperature should be within the range 25-28°C
There is fermentation that take place during and after mixing to produce CO2 gas
Fermentation also yields alcohol and other by products that give bread its flavor
Procedure of straight dough method
1. Put all ingredients into the mixing bowl (except shortening)
Ingredient quantity required
Flour 100%
Dry yeast 1-3%
Yeast food 0-1%
Shortening 5%
Skimmed milk powder 0-3%
Sugar 5-8%
Salt 2%
Water 60-62%
Emulsifier 0-0.3%
Dough temperature 26-27%
Fermentation time 2-2½ hours

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2. Start to mix, first use a low speed for 1-2 minutes, then increase to medium speed. The
low speed at the start point prevent the mixer from scattering the dry ingredients
3. Add shortening after the cleanup stage. When shortening is added at the beginning, itt
prevents water molecules from dehydrating the dry ingredients this increase mixing time
4. Stop mixing and observe for the characteristic of well-developed dough
5. Ferment the dough (first proofing). The dough is left in the fermentation room with the
right temperature (27-29°C) and the right humidity for about 2 hours or until it doubles in
size
6. After first proofing take the dough to the dividing section where the dough is cut into
portions of the required sizes then molded and placed into prepared baking tins
Preparation of baking tins
Baking tins are basically prepared by applying a thin film on layer of shortening, the dusting
with flour before putting the dough or butter
7. Second proofing- the dough in the baking tins are given second proofing at the same
temperature, humidity and time until it's double in size
Finally bake the cake at temperature of below 180-209° C for about 24 minutes
Sponge dough method
This method has a preferment stage called sponge
Sponge consists of 60-80% of the total flour (usually 70%) all the yeast food and the rest of
the drying ingredients and 55-60% of all the liquid
The mixing time is low speed for 1st 3 minutes then medium speed
The storage is usually stiff and it's mixing temperature 23-25°C proofing time of the sponge is
3½-4½ hours
Procedure
Put 70% of the flour, all the yeast, all the yeast food and other dry ingredients + 60% water in
the mixing bowl
Start to mix at a low speed for the 1st 3 minutes i.e. avoid scattering of dry ingredients and
then at a minimum speed
Ferment or proof the sponge at 29°C for 3½ hours
Add the remaining flour and water into the matured sponge
After the cleanup stage add shortening
Take the dough to the dividing section, mold it and take it to appropriate baking tins
Take the dough to the second proofing until it doubles the size

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Bake at appreciate temperature and time
Comparison between the two methods
✔ Reduced processing time, labor, power and equipment
✔ Less fermentation loss (by adding shortening)
✔ Gives good flavor to final products

Advantages of sponge dough method

i Less amount of yeast is used because of length of proofing time
ii It gives better texture and grain for final products because of the double mixing there
is more uniformity in texture of products
Fermentation
In bread making, fermentation is the action of microorganisms (specifically bacteria and yeast
breaking down organic materials to produce CO2, alcohol, amino acids, esters, organic acid
etc.
Functions of fermentation
1. Yeast produces several fermented materials. In the dough which gives flavor and taste to
the final product. These fermented products include; ethyl alcohol, organic acid (acetic
acid), esters (ethyl ethanoate), Carbonyl compounds (aldehydes and ketones)
2. During fermentation, the gluten is swelled by the heat and the acid produced as well as
the carbon dioxide produced. This gives extensibility and elasticity to the dough giving it
a longer volume
3. Oxidation and CO2 production push the gluten structure giving it a web like look. This
gives the dough a bigger capacity for gas retention
THE ROLE OF YEAST IN THE DOUGH
Yeast consumes sugar in order of priority;
If there is inverted sugar in the dough, the yeast will consume glucose first e.g. sucrose is
inverted to fructose and glucose. The yeast will consume glucose first
Lactose is not consumed by yeast and therefore it reacts with amino acid in the mallard
reaction
Lactose can however be broken down by lactic acid bacteria naturally found in wheat
During the manufacturer of yeast some enzymes are pretreated to help during fermentation

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ACIDIFICATION IN THE DOUGH
Wheat flour contains lactic acid bacteria and acetic acid bacteria
Lactic acid bacteria acts on lactose present in milk to produce lactic acid
The lactic acid is further broken down into butyric acid, hydrogen and CO2 thereby reducing
the pH of the dough to between 4 and 5
Acetic acid is a weak acid produced by the action of acetic acid bacteria on alcohol produced
during bread making. It doesn't make such a big difference in the pH of the dough
Acidification is very important because it has effects on hydration, swelling of the gluten,
enzyme activity and chemical reactions that are important in bread making
Osmotic pressure in the dough
Yeast is a microorganism whose cell activity can be inhibited by high osmotic pressure
In bread making osmotic pressure is brought about by the amount of sugar and salt
Sugar should not be above 15% as this inhibits yeast activities due to high osmotic pressure
Salt should not be above 2%

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Generation and retention of CO2 gas
There are many factors affecting gas generation. Those that increase gas
production/generation include;
a) High yeast concentration
b) Correct amount of sugar
c) The right amount of yeast foods
d) Correct temperature (38°C)
e) pH value of between 4-5
Conditions of the fermenting yeast dough
Yeast activity is best at between 38-40°C
The temperature for fermentation room is usually 27-29°C because the length of time for
fermentation or proofing allows for complete yeast activity
The relative humidity of the fermentation room should be between 75-80%. Less than 75%
result in a dry dough surface which retards fermentation because it doesn't allow the gluten to
stretch any more
Punching
This is a procedure for a straight dough method of bread making
It is done as follows;
✔ Knead the dough using hands to equalize the gas throughout the dough and to
introduce oxygen
✔ Fold the sides of the dough towards the center and continuous kneading

Reasons for punching

a) To equalize temperature throughout the dough, this ensures uniform fermentation
b) To ensure uniform texture and grain
c) To introduce oxygen which enhances enzyme activity
NB: Punch is done when 60% of the fermentation has taken place
Making up process
This process consists of dividing, molding, rolling, panning and final proofing
Dividing
Is the first process in the making up the process
The aim of dividing is to cut off the dough into pieces of the desired weight

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In large commercial industries a divider machine is used
The divider consists of knife that cuts the dough into the desired size
It also consists of a plunger which pushes the dough into a chamber. The chamber then drops
the dough to the next step
Molding
The aims of molding are as follows;
i To make uniform dough pieces as far as shape is concerned
ii To seal the opening made during dividing so as to retain the generated gas
Panning
Is putting the molded dough into the correct size of a baking tray of tin
The seam of the dough should be put at the bottom of the pan to prevent it from opening
during baking
The dough should always be put in the correct size of the baking tins
Final proofing
If the panned dough is baked immediately the final product will be small, will have a dense
grain and coarse texture
This is because of too much handling of the dough during punching, dividing, molding and
panning
The dough needs to be allowed to complete fermentation and regain texture and grain
This process is called final proofing
The temperature is between 35-38°C and humidity 75-80%
THE BAKING PROCESS
There are three main types of oven;
✔ Peel oven
✔ Reel oven
✔ Tunnel oven

Peel oven
Is a small scale oven convenient for home and small scale bakeries
It consists of several shells upper and lower heating elements and control knobs for
temperature and time

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Tunnel oven
It is recommended for commercial production and it behaves like a conveyor belt
It has an entry point for fresh dough and an exit point for baked bread
Between the entry point and the exit is approximately 25 minutes
The tunnel moves at a slow speed to allow for the bread to bake
It also consists of control knobs but mostly a start and stop knob when the oven is not in use
Reel oven
A properties in between the peel and tunnel oven
BAKING STAGE
This is the final and the most important stage or section in bread making
There are there stages involved in bread making
The first stage last about 6 minutes, in this stage CO2 gas will expand giving the bread
maximum volume to increase and other changes e.g. gelatinization and coagulation of gluten
takes place
This stage lasts about 12 minutes
The last stage which lasts about 6 minutes serves to give bread color and firmness to the side
walls of the bread
THE BAKING REACTION
There are three reactions that take place during the baking of bread;
A. Oven spring
When the dough is put into the oven it dramatically expands. This expansion is called oven
spring
Oven spring is caused by the following factors;
i There are numerous gas cells in the dough. The gases begin to increase in pressure due
to the heat and then expand the cell walls of the dough
ii Some of the generated CO2 is soluble in the dough moisture. The released gases also
increase the pressure in the cells
iii High temperature increases vapor from the liquids and this vapor also expand the cell
walls
iv High temperature stimulates yeast activity and this maximizes CO2 production
B. Starch gelatinization and gluten coagulation

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Both of these form the skeleton of the final product
Starch gelatinization begins at 54°C and ends at 95°C
The degree of gelatinization depends on the availability of moisture
Gluten coagulation begin at 74°C and continuous until the end of baking
Gluten loses its affinity for water and therefore it releases the water within it
Moisture or water distribution occurs from the gluten phase to the starch phase
Gelatinization- the process of breaking down the intermolecular bond of starch molecules in
the presence of heat and water allowing hydrogen bond to engage more water
C. Coloring and flavoring
These two involve caramelization and mallard reaction
NB: The temperature on the oven depends on the size of the dough and the formula
A large amount of dough should be cooked at a lower temperature to allow the changes in the
crumb to take place before the crust is burnt or cooked
Sugar and milk are sensitive to high temperature and therefore formulae with these two
ingredients should be baked at a lower temperature
Bread cooling
Bread must be allowed to cool after baking
If bread is wrapped without cooling moisture condensation will occur in the surface. This
encourages mold to grow rapidly
It also increases the chances for stalling
Immediately after baking, the outer zone of the bread its higher in temperature but lower in
moisture than the interior
During cooling moisture moves from the interior to the outer zone
Bread should therefore be given time to completely cool before wrapping
Keeping quality of bread
Staling
Baked bread is subjected to a progressive deterioration in quality. This is referred to as staling
Bread and cakes stale faster than cookies because they have more moisture
In bread there are two types of staling;

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 ● Crust staling
● Crumb staling
● Crust staling

Crust staling
The crust is relatively dry, crisp and brittle when fresh
Upon staling the crust become soft and leathery
The main reaction that occurs in crust staling is the transfer of moisture from the interior of
the loaf to the crust
The wrapping of bread in a moisture proof paper contributes to the staling rate of the crust
If the relative humidity of the air is high crust staling is accelerated
Crumb staling
When fresh the crumb is soft, upon staling it becomes hard and brittle
Crumb staling is caused by:
Loss of moisture if bread is exposed
Starch retrogradation; with time there is a decrease of gel formation within the starch which
presents as the hard texture of the crumb
The crumb also loses flavor upon staling
Stale retarding agents
Agents that can be added during dough making to slow down the chemical reactions that lead
to staling
They introduce changes in starch behavior which yields a more stable condition
They include the following;
i Emulsifiers- slow down the change that takes place in starch granules
ii Potatoes starch- yields a stable condition which also slows down the starch retro
gradations
iii Dextrin- also help in the keeping quality of bread. However the best method to retard
the staling of bread is proper dough fermentation
Methods of measuring staleness
1. Use of compress meter
When the bread crumb is fresh it is easily compressed

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The compress meter is a machine that is able to measure how much the crumb can be
compressed
It has the following parts for this function;
▪ Adjustment knob for slice thickness
▪ Indicator for slice thickness
▪ Scale indicator
▪ Plunger
2. Swelling test
Fresh crumb swells more than stale crumb
The degree of staleness of the crumb dictates how much water will be absorbed by the crumb
3. Crumbliness test
As bread stales the crumb becomes brittle for this reason when the crumb is pressed it gives
bread crumbs more easily
4. ROPY bread
It is caused by bacteria called bacillus mesentericus. This bacteria form highly heat resistant
spores. The enzymes in the bacteria breaks down the protein and starch in the bread
With time when the bread is pulled apart, fine, silky threads can be seen
The spoiled bread also smells like an overripe watermelon and the interior is soft and sticky
with brown discoloration
NB: The main source of infection is flour and yeast. The bacteria can be prevented by a pH of
below 5
For this reason, properly fermented dough is hardly affected by bacteria
CAKES AND BISCUITS MAKING
The ingredients used in cakes and biscuits are different from those of yeast products e.g.
bread
The main difference is that for yeast products, yeast is the main source of CO2 as the raising
agent
In cakes and biscuits the raising agents are CO2 from bicarbonate of soda, air and steam
The other difference between cakes and yeast products is the method of mixing and the
specific spices used for each of these products
The main ingredients for cakes and biscuits are;
Flour

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Flour used for cakes and biscuits are obtained from soft wheat
This flour does not develop a tough dough during mixing
It contains soft gluten which ensures formation of fine foam
Cake flour is also treated with chlorine for the following reasons;
i To lower the pH to between 4.5-5.0
ii To soften the gluten
iii To improve grain and texture
Shortening (refer to bread making for functions)
In cake making fats are used for holding and retaining air. This air expands during baking to
give the product volume
Eggs
Eggs are used more in cake making than in bread making. They play the following important
functions;
a) The binding actions- eggs especially egg white can be whipped into a foam (egg white
has the whipping while egg yolks prevent whipping). Proteins are denatured during
whipping and they form a stable aerated structure. During baking these network
coagulates and maintain a rigid structure giving the baked products volume
b) Leavening/raising action- the whipped eggs are able to hold and maintain air and these
air cells expand during baking to give product volume
c) Tenderizing action- the egg yolk contain lecithin which is a natural emulsifier
d) Enhancing flavor- eggs have an acceptable enriching baked products
e) Eggs enhance nutritive value- eggs are rich in proteins, fats, vitamins e.g. E and
minerals. These highly enrich the baked products
Leavening agents ( baking powder)
Functions are;
✔ Give volume to the baked products
✔ Tenderize the crumb giving a uniform cell structure and soft texture

Baking powder is the typical leavening agent used for cakes and biscuits. It's composed of
sodium bicarbonate, acid reacting agent and ammonium carbonate
Examples of acid reacting agents are; tartaric acid, sour milk, honey etc.
Bicarbonate of soda can be used on its own without the acid reacting agent but it yields only
50% of the CO2
When the acid reacting agent is included, almost 100% CO2 will be received

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Baking powder exist as a white powder with the NaHCO3 and acid reacting agents being kept
separate by a starch during storage
Any introduction of moisture to the baking powder gives a bitter taste to the final products
and streaks of poor color (yellow) within the finished products
Spices and flavors
Spices are classified according to the part of the plants from which they are derived
For example:
Sesame- for topping of bread
Nutmeg, all spice, turmeric- fruit spices (doughnuts, cakes and cookies)
Cloves- flower spices (cakes and cookies)
Ginger- underground stems (cakes and cookies)
Cinnamon- best for cakes cookies and bread
Caraway- seed spice (cakes and cookies)
Colander-
Flavors
They are either natural or synthetic. They can come from essences or oils e.g. vanilla,
strawberry and lemon/orange
Synthetic flavors are chemically made and therefore any flavor can be achieved this way
Sugar (refer to bread making)
METHODS OF CAKE MAKING
Sugar- butter method (creaming)
The basic formula is as follows;

Ingredients percentage
Fats (margarine, butter) 100%
Sugar 100%
Eggs 100%
Vanilla 1%

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Baking powder 2%
Salt 1%
Flour 100%
Water 16%
Procedure
The fats and sugar are mixed to achieve a fluffy whitish mass or a material called sugar fats
Whole eggs are beaten separately and mixed into the sugar fat mixture gradually
Sieve the flour and the rest of dry ingredients to incorporate air and have a good texture
Fold in the flour and the dry ingredients into the sugar butter mixture
The butter is put into prepare baking tins and baked at a temperature and time appropriate for
its size. (150-200°C) time (35 minutes -1½ hours)
Do not open the door of the oven before the butter stabilizes and solidifies
Flour butter method
Fats and the flour (and starch) are mixed together until a fluffy mass is absorbed
Eggs and sugar are whipped together until a semi-firm foam results
The sugar and eggs is combined with the fluffy mass of fats and the flour
The rest of the ingredients are added and incorporated. The advantage of this method is to be
able to make an effective dispersion and distribution of the fats throughout the butter.
However, this method requires mixture. The rest of the procedure is as sugar butter method
Single stage method
This method is literally a single method. All ingredients are put into the mixer and then mixed

METHOD OF THE BISCUIT MAKING

There are hardly any differences between biscuits and cookies
They are called biscuits in Europe while they are called cookies in the United States
There are three methods of biscuit making;
a) Stamped type biscuits

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This dough is quite stiff and lean. The dough is mixed for a fairly long time and then sheeted
by roller. The sheeted dough is cut with a cutter, which has various shapes i.e. circle, triangle,
and rectangle
b) Drop type biscuits
This is soft dough. The dough is put into the hopper of the depositor or the pastry bag then the
dough comes out of the baking tray from the nozzle, which has many kinds of shapes such as
rosette shapes, pear shape, finger shape, star shape etc.
After depositing, the deposited dough are often decorated with many kinds of materials on top
c) Wire cut biscuits
The dough is put into the hopper of the depositor and dough comes out through the die and
then us CT to the desired length with wire. As there are many shapes of dies , so many
various types of biscuits are baked
Wire cut biscuits are devoid of top decorative designs
Baking
Biscuits should not be baked until crisp. Because the biscuits are continued to be baked and
dried on the hot tray after being removed from the tray after being removed from the oven
When the grease is applied on the tray, it should be done carefully. Excessive grease on the
tray causes unexpected spread of the biscuits
Pasta production
Pasta products were first introduced in Italy. Today they are manufactured in huge/large
production industries and they are three main products;
✔ Dry macaroni
✔ Spaghetti
✔ Noodles

The initial production processes are the same but the difference arise in the ingredients used
PASTA MAKING PROCESS
Pasta products are produced using hard wheat, macaroni and spaghetti and soft wheat for
noodles
Dry macaroni is made mainly using water and wheat flour
On the production of noodles and spaghetti other ingredients such as spices, herbs, eggs can
be added
Raw materials

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Pasta products contain milled wheat, water and optional ingredients such as eggs, herbs and
spices
The durum wheat is mainly used for pasta products
Semolina is the soft wheat used for soft products such as noodles
The water used should be free from off-flavors and clean for human consumption. The water
should be of very low bacteria count because pasta is produced below pasteurization
temperature
Eggs are normally added to spaghetti but mostly noodles
They improve the nutritional quality and richness of the pasta products
Small amount of optional ingredients such as salts, garlic, ginger may also be added to
enhance flavor
Disodium phosphate is added to shorten cooking time
Wheat milling
In pasta production wheat is milled in specific ways to achieve the desired products. This
depends on the pasta products to be made
For dry macaroni, spaghetti and noodles, different types of wheat are required
Mixing
In the mixing operation water is added to milled wheat produce a dough with the moisture of
about 31%
Most modern pasta pressers are equipped with vacuum chamber to remove any air bubbles
from the dough before the next year
If air is not removed it will form small air pockets in the pasta, reducing its mechanical
strength exposing it to breakage during storage or transportation
Extruding
After the dough is mixed, it is transferred to the extruder
This is a machine that mixes the dough into a homogeneous mass and forces the dough
through dies or openings of different sizes and shapes
The extruder also controls the rate at which the dough is moving
The extruder also has water control jackets which keeps the dough moist for a smooth
extrusion process
The temperature in the extruder should be about 61°C because above 74°C the pasta will be
damaged

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Uniform flow of the dough through the extruder is important
Products from the non-uniform size cannot be package together
If the product is non-uniform, they are discarded or re-processed
Drying
Is the most difficult and critical step in the pasta production process. The objective of drying
is to lower the moisture content from above 31-12%
This moisture maintains the product hardness, shape and ensures storage without spoilage
It's done immediately after extrusion to prevent the pasta from sticking together
Drying is done in two stages;
● Pre drying- hardens the outside surface of the pasta keeping the inside soft. This
facilitates cutting where need to be without the product sticking together
● Final drying- used to remove most of the moisture from the products. Drying is also
done slow, because very quick drying will crack the product. However, if it is done
too slowly, the product may become moldy in the process
Packaging
Packaging keeps the product from contamination. It also protects the product from damage
during transportation and storage
The package should be able to supply the products favorably therefore most of the primary
packages are transparent but hard enough to protect the products
The secondary packages are harder and box like in nature for easy packaging. They also
provide protection for the products
Both the primary and secondary packages should have a description of the product
Types of pasta
There are different types of pastas whose name originates from the shapes
Long form/stand pasta
This is mostly used for spaghetti production and it's usually twisted along the folk while
eating
It comes with different lengths
Ribbon pasta
Made with an extruder whose die is ribbon shaped. It's mostly for dry macaroni
Tubular pasta

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This is tube shaped and can be whole or cut into halves
It's mainly for macaroni products
Shaped pastas
Usually for macaroni and is in very may varieties of shapes
Stuffed pasta
Contains many optional ingredients
Very soft easy to cook and suitable for noodles

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