2. INTRODUCTION
Bread is a staple foodstuff, which is made and
eaten in most countries around the world.
Bread is a yeast leavened product.
3. The character of bread and other fermented products depends heavily on the
formation of a gluten network which traps gas from yeast fermentation and makes a
direct contribution to the formation of a cellular crumb structure which, after baking,
confers texture and eating qualities quite different from other baked products.
Crumb structures of most baked breads and you will find that the common linking
theme is that they are formed of holes of differing shapes, sizes and distributions.
Each hole is embraced by a network of connected strands, coagulated gluten, in
which starch granules and bran particles are firmly embedded.
When this crumb is subjected to pressure with the fingers it deforms, and when the
force is removed it springs back to assume its original shape, at least when the
product is fresh.
This combination of a cellular crumb with the ability to recover after being
compressed largely distinguishes breads from other baked products these are the
very characteristics that bakers seek to achieve in most bread products
4. PURPOSE OF DOUGH MIXING IN BREAD
MANUFACTURING PROCESS
While there are many different bread making processes, they have the common aim of
converting wheat flour and other ingredients into a light, aerated and palatable food.
The unique properties of the proteins in wheat with their ability to form a cohesive mass
of dough once the flour has been hydrated and subjected to the energy of mixing, even
by hand, provides the basis of the transition from flour to bread.
This cohesive mass is the ‘gluten’ and once it has formed into a dough it has the ability
to trap gases during fermentation, proof and baking which allows the mass to expand to
become a softer, lighter and more palatable as a food after baking.
The combined effect of these rheological changes during mixing and fermentation is for
the baked mass to increase in volume and give a product with an even softer, more
digestible character and different flavor.
5. RAW MATERIAL INVOLVED
Flour:
Hard wheat containing 11.5% to 13% protein and a moisture content of 14% is used. The
amount of water required to produce a dough of standard consistency can be found by
farcinograph which also gives the indication of mixing time and gluten strength.
Yeast:
The quantity of yeast employed in a bread determines the time required for the formation.
concentration of yeast used is about 2-2.75% of the flour weight permit efficient bread
production to inhibit the yeast activity .
Water:
he optimum proportion of water or milk for a good loaf volume varies with the hydration
capacity of the gluten in the flour. This proportion is reported to vary from 51 to 71%. Good
bread flour requires 60-65% of water.
6. Sugar:
Sugar is used as nutrient for yeast in bread production . It also modifies the bread
flavour
Salt:
About 1.5-2% of salt is added to bread. Salt helps to stabilize fermentation,
strengthens the gluten and develop flavor, owing to its effect on the flavor of other
ingredients.
Fat:
A small amount of fat (<3%) added lubricates the dough and helps the gluten to
stretch, yielding a loaf with greater volume in addition to contributing flavor.
7. BREADMAKING PROCESS
The process of manufacture of bread starts with mixing
and formation. Mixing of dough is carried out by:
1. Straight dough method
2. Sponge dough method
3. Charleywood process
4. Spiral mixing and no time dough method
8. STRAIGHT DOUGH METHOD
Straight dough method involves mixing of all bread
ingredients together at about 80˚F.
It is also called the direct dough method and is
commonly used in India
The quality bread depends upon the thorough mixing
of all components and proper kneading.
9.
10. Sponge and dough method
Elements of the processes are similar to those for bulk fermentation in that a
prolonged period of fermentation is required to effect physical and chemical
changes in the dough. While in sponge and dough method only part of the
ingredients are fermented—the sponge. Sponge fermentation times may vary
considerably, as may their compositions
11. The key features of sponge and dough processes are as follows:
• A two-stage process in which part of the total quantity of flour,
water and other ingredients from the formulation are mixed to
form a homogeneous soft dough—the sponge.
• The resting of the sponge so formed, in bulk for a prescribed
time, mainly depending on flavour requirements.
• Mixing of the sponge with the remaining ingredients to form an
homogeneous dough.
• Immediate processing of the final dough after mixing.
12. The sponge contributes to flavour modification and the development of the
final dough. The process of flavour development in the sponge, though
complex, is observed as an increase in the acidic flavour notes arising from
the fermentation by the added yeast and other microorganisms naturally
present in the flour.
To maintain the right flavour profile in the finished product the sponge
fermentation conditions are closely controlled and care is taken to avoid a
build-up of unwanted flavours.
Improver additions are commonly made in the dough rather than the sponge.
Flours used in typical sponge and dough production will be at least as strong
as those used in bulk fermented dough with protein contents not less than
12%
13. Preparation of ingredients (weighing)
Sifting and blending flour
Tempering of water
Preliminary mixing of yeast
Sponge mixed
Sponge placed kin trough
Sponge allowed maturing (proofing)
Sponge broken up and mixed with dough ingredients
Allowed to rise sometime turned and folded
Dough dividing
Dividing and scaling
Rounding
Intermediate proof
Moulding
Panning
Pan proof
Slicing
Cooling
Baking
14. Advantages and Disadvantage of Straight
Dough and Sponge and Dough Method
Advantages :
Straight dough method:
1. The advantage of straight dough method over sponge and dough
method lies in saving of time and labour, as all ingredients are
mixed at a time.
2. The length of the time can be controlled according to the amount of
yeast, salt and sugar.
3. The straight dough method is simple.
15. Disadvantage:
1. A straight dough method requires more mixing than a sponge
and dough method or gluten must be worked for more
elasticity.
Advantages:
Sponge and dough method:
1. Sponge and dough method requires less yeast.
2. A greater volume, soft and white crumb is produced by
sponge method.
16. Chorleywood bread process
Compared to the older bulk fermentation process, this process enables to
use lower protein wheat, and produces bread in a shorter time.
The Chorleywood bread process allows the use of lower-protein wheats
and reduces processing time, the system being able to produce a loaf of
bread from flour to sliced and packaged form in about three-and-a-half
hours.
This is achieved through the addition of Vitamin C, fat, yeast, and intense
mechanical working by high-speed mixers.
17. Flour, water, yeast, salt, fat, and, where used, minor ingredients common to
many bread-making techniques such as Vitamin C, emulsifiers and
enzymes are mechanically mixed for about three minutes.
The high-shear mixing generates high temperatures in the dough, which is
cooled in some advanced mixers using a cooling jacket. Chilled water or
ice may also be used to counteract the temperature rise during high-speed
mixing. Air pressure in the mixer headspace can be controlled to keep gas
bubbles at the desired size and number. Typical operating regimes are
pressure followed by vacuum, and atmospheric followed by vacuum. The
pressure control during mixing affects the fineness of crumb texture in the
finished bread.
Baking takes 17–25 minutes at 450 °F (about 230 °C
18. Spiral mixing and no-time dough
processes
In many of the smaller bakeries around the world a no-time dough-making process has
evolved based on mixers running with a single, vertical S-shaped mixing tool. Typically
the bowl will rotate and often there is a single, vertical, fixed bar to enable greater
energy input to the dough. Mixing speeds are somewhat lower than those seen with the
CBP or sponge and dough bread making methods and energy inputs are also somewhat
lower.
After mixing the dough may be given a short period of fermentation in bulk before
dividing.
Spiral mixers are more effective at incorporating air during mixingand therefore have a
greater potential to make more effective use of ascorbic acid. However, the bread cell
structure which comes from this type of mixing is more open (i.e. larger average cell
size)