+
France
Baguette
Mexico
Tortillas India/
Pakistan/Iran
Naan
Germany
Sourdough
bread Italy
Focaccia
China
Bun
+
The history of bread
One of humanity's oldest foods.
The first bread was unleavened
Dough is made by just flour and water
It was flat, similar to a Mexican tortilla.
Unleavened Bread
Mexican tortilla
+
The history of bread
Around 5,000 years ago the Egyptians started producing
fermented bread (Yeast Bread)
The Egyptians used little old dough with the new one, these
two dough were combined together and kneaded and then
were set to rise.
This made the dough more spongy and the bread had more
volume.
+
Unleavened Bread and Passover
Bread was part of everyday life, as well as special occasions
(religious, funerals, etc)
Unleavened bread is a wide variety of breads which are not
prepared with raising agents (e.g yeast, baking powder etc.)
+
The history of bread
Until the mid-18th century white bread was only
consumed by the more wealthy, as it was more
expensive.
Today, white bread and wholemeal bread are
equally affordable.
+ Different types of grains
used in bread making
Wheat 小麥
Wheat is the most commonly used grain
for bread.
Wheat is not only used for bread, but
also for making many other products,
such as cakes, muffins, crumpets,
croissants, pastries, pizzas and biscuits.
+ Different types of grains
used in bread making
Rye 黑麥 is also commonly used for
bread making.
It is traditionally used for bread making
in Central Europe.
Flour from other types of grains such as
oats, barley, corn, spelt or kamut can also
be used for bread making, but these are less
commonly used.
+ The structure of a grain
Endosperm – this is the largest component of the grain and
contains the ‘floury’ bit of the grain, which is white.
Bran – this is the outer layer or ‘skin’ of the grain; it is darker than
the endosperm.
Germ – this is the seed. It is the smallest part of the grain and sits
between endosperm and bran; it is rich in nutrients.
+ The principal ingredients of
bread
Flour
When flour is moistened and stirred, beaten or kneaded,
gluten develops to give the dough ‘stretch’.
What are the two major ingredients of
flour?
Bread Flour
High in gluten protein
~12.5-14% protein
Gluten is a protein naturally present in wheat and
is what makes the dough ‘stretch’.
Cake Flour
Low in gluten protein
~8.5 - 9.5% protein
+
Types of Flour
Strong flour:
High in protein and gluten
For bread making
Soft flour:
Low protein content, high in starch.
For cakes and biscuits
+ Wheat facts
The protein content of wheat is important in bread making as it
has a significant impact on the finished product.
Flour made from wheat that is high in protein/gluten is called
‘hard’ or ‘strong’ wheat, whereas flour with a lower protein content
is called ‘soft’ or ‘weak’.
Gluten is a protein naturally present in wheat and is what makes
the dough ‘stretch’.
+ What is Gluten?
Gluten: The rubbery mass that is left when wheat flour is
washed with water to remove starch, non-starchy
polysaccharides, and water-soluble constituents.
• Gliadin and Glutenin are two fractions of
Gluten , a major wheat protein.
Dough
Wash out starch granules
Gluten
Mix with alcohol/water
Insoluble Soluble
Glutenin Gliadin
+
Gluten formation
Glutenin Molecules
When flour is mixed with
water and made into a dough,
glutenin protein molecules
link up end-to-end to form
long, composite gluten
molecules.
Gluten Molecules
Varieties of gliadin and glutenin cross link together through
disulfide, ionic and hydrogen bonds to form gluten.
• http://scialert.net/qredirect.php?doi=jas.2010.2478.2490&linkid=pdf
• Belton, P.S., 1999. On the elasticity of wheat gluten. J. Cereal Sci., 29: 103-107.
+
Gluten formation
As this fluid is stirred, it quickly
When water is first added to flour,
develops into a tangle of fibers as
the gluten proteins are randomly
the gluten proteins form
oriented in a thick fluid.
elongated bundles of molecules.
+
Microscopic Picture of Dough
air bubbles
gluten
starch granules
Making high quality dough
Gluten is formed when two
classes of water-insoluble
proteins in wheat flour (glutenin
and gliadin) are hydrated with
water and mixed.
Only dough can contain gluten, not the
raw flour alone.
Molecular interpretation of gluten development
a) Beginning of mixing;
optimal mixing;
Over-mixing
The mechanical shear causes the
gluten bonds to form and become
a viscoelastic matrix holding the
starch granules and water in the
flour.
http://scialert.net/qredirect.php?doi=jas.2010.2478.2490&linkid=pdf
+ https://www.youtube.com/watch?v=zDEcvSc2UKA&spfreload=10
+ The principal ingredients of
bread
Yeast
Yeast is a living microscopic organism that
converts sugar or starch into alcohol and carbon
dioxide;
Yeasts are naturally present in grains, but yeast is
added during bread making to speed up the
process;
It is needed for the dough to rise through
fermentation and to form bread crumb;
Yeast is also important for the typical flavour and
aroma of bread;
High temperatures during the baking process
kill any live yeast cells.
+
What is yeast?
• Yeast are single-celled fungi
• The scientific name for the yeast that baker’s use
is Saccharomyces Cerevisiae, or “sugar-eating
fungus”
Fresh Yeast
+
Active dry yeast
Active dry yeast is the form of yeast most commonly
available to non-commercial bakers.
Consists of coarse oblong granules of yeast, with live yeast
cells encapsulated in a thick jacket of dry, dead cells with
some growth medium.
Active dry yeast must first be rehydrated.
+ Which gas is produced by
yeast during the
fermentation process?
Oxygen
Nitrogen
Air
Carbon dioxide
ANSWER: During the fermentation process carbon
dioxide is produced, which causes the dough to rise.
+
FERMENTATION:
Theprocess that allows the dough to rest in a warm
place in which the yeast acts upon the sugars in the
bread dough to form alcohol and carbon dioxide.
+
Fermentation
The alcohol evaporates during baking
Time depends on the amount of yeast,
temperature of the room and the kind of flour.
The dough should be at least double in volume.
To check…gently push 2 fingers into the dough.
If an indentation remains, the dough has risen
enough.
+
Activity: Observing
the activity of yeast
Materials provided:
Sugar, water,
balloon, water
bottle
Say Hi to the yeast!
+
Another method for creating CO2
in bread
Two basic methods for creating carbon dioxide:
Using baking soda, baking powder to create a chemical
reaction that yields the gas
Using yeast in a biological process to create gas
+
Baking Soda
Baking Soda = chemical compound
sodium bicarbonate (NaHCO3)
Bakingsoda releases sodium carbonate as well as carbon
dioxide when heated
Releases CO2 according to the equation:
2NaHCO3 → Na2CO3 + CO2 + H2O
Sodium carbonate Na2CO3 gives food a bad taste and a yellowish color.
However, baking soda is always used with an acid, which alters the
chemical reaction to prevent sodium carbonate from forming
Some examples of acid are buttermilk, vinegar, lemon juice,
molasses, honey, fruits, fruit juices, and cream of tartar.
+
Baking Powder
Baking Powder = leavening compound that
contain baking soda, dry acids and starch or
some other filler.
The filler in baking powder, usually cornstarch or
calcium carbonate, absorbs moisture in the air,
which helps prevent a chemical reaction from
taking place too soon.
CO2 is generated from the acid-base reaction:
NaHCO3 + H+ → Na+ + CO2 + H2O
+
Baking powder
Baking powder comes in two types:
1. Single-acting baking powder = as soon as liquid is added,
carbon dioxide starts to be released
– The quick reaction occurs because the acid in
baking powder is soluble in a cold liquid
2. Double-acting baking powder = usually preferred,
contains two acids, one that reacts with cold liquid and
one that reacts with heat.
– Some carbon dioxide is released as soon as liquid
is added, but most is produced as the batter heats
in the oven
+ https://www.youtube.com/watch?v=qylxpwNhFYI
+ The principal ingredients of
bread
Salt
Although it is usually used in small amounts, salt
is an essential ingredient in bread.
It helps to strengthen the gluten and helps the
yeast during fermentation and is therefore
important for good volume and texture.
Water
Water is needed to form the dough.
+ Other ingredients of bread
Fat – vegetable fat is used in very
small quantities to keep the bread
soft.
Flour treatment agents – the most
commonly used is vitamin C; it is
used to strengthen the dough and
keep it soft.
Emulsifiers – these are based on
vegetable oils and are used to
provide dough stability and improve
volume.
+ Other ingredients of bread
Enzymes – these can be added to
supplement the enzymes naturally
present in flour to minimise variations
cause by climate and soil quality. They
are destroyed by heat.
Preservatives, such as vinegar, to
increase the shelf-life of bread.
Soya flour to strengthen the dough and
give it better structure.
+
INGREDIENTS AND FUNCTIONS
IN A YEAST BREAD
INGREDIEN T FUNCTION
FLOUR STRUCTURE, FORMS GLUTEN
YEAST LEAVENING AGENT
LIQUID MOISTEN
SALT FLAVOR
SUGAR FOOD FOR THE YEAST
FAT TENDERNESS AND RICHNESS
EGGS STRUCTURE, FLAVOR, RICHNESS
+ The 4 key steps of bread making
https://www.youtube.com/watch?v=VrUdtzXquWk
1. Mixing/kneading
The ingredients are mixed together
and kneaded.
Kneading is required for the
development of the gluten and to
incorporate air bubbles.
The gluten structure is also required
to catch the gas produced during
fermentation.
+ The 4 key steps of bread making
2. Proving/fermenting
During this step some of the starch
present in flour is broken down and is
fermented by the yeast and other raising
agents.
Production of carbon dioxide which
causes the gluten network to expand
and therefore makes the dough rise; the
produced gas is trapped in pockets.
The quality of gluten is important – if it is
too weak bubbles can burst causing a
lack of volume, if it is too strong the
dough won’t stretch enough.
+ The 4 key steps of bread making
3. Baking
this step is required to produce a solid
structure and deactivate the yeast.
4. Cooling.
