Introduction to flour milling

3. Wheat Flour Milling
Wheat Flour?
 Wheat flour is a powder made from the grinding of wheat
used for human consumption.
Wheat flour is the most common flour used in baking.
There are different types of wheat flour, and they're
distinguished by the amount of gluten they contain.
 Wheat is unique or its protein content (gluten).

4. What is Gluten?
 Gluten is protein composite( gliadin and a glutelin) found
in foods processed from wheat and related grain species,
including barley and rye.
 It gives elasticity to dough, helping it to rise and to keep
its shape, and often gives the final product chewy texture.
 It gives baked goods their structure. When dough is
kneaded, these glutens develop and become firm.

5. • Whole grain flour contains all grain
parts
• Refined, enriched flours are made from
the endosperm only
• Endosperm (83% of kernel)
Energy for plant growth
Carbohydrates; protein for people
• Bran layers (14.5% of kernel)
Protects seed
Fiber, B-vitamins; minerals
• Germ (2.5% of kernel)
Nourishes seed
Antioxidants, Vitamin E, B-vitamins

6. The basic aim of the milling process
-to break the wheat grain, remove the outer bran layers and the
germ .
-to grind the pure endosperm into flour.
This is achieved by a gradual series of operations including
-a breaking stage,
-a reduction stage and
-a series of separations of the ground material by means of both
particle size and density.
THE MODERN FLOUR MILLING PROCESS

8. First wheat is cleaned and conditioned to a suitable moisture
level for milling before passing through the BREAK ROLLS.
The break rolls consist of pairs of fluted rolls running in opposite
directions at a differential speed so that both a shearing and
grinding action is produced.
The stock from the first roll is sieved in a plansifter and branny
material with endosperm adhering is separated and sent to the next
set of break rolls.
Wheat Flour Milling

9. Coarse endosperm chunks (SEMOLINA) and finer endosperm
particles (MIDDLINGS) are separated in the purifier and sent to the
reduction rolls.
Any remaining fine bran particles may be removed by the purifier
using a combination or sieves and air currents.
Generally, four break stages are used with successively finer flutings
and gap settings for each stage.
After the final break stage, bran is removed as commercial mill bran.
The coarse endosperm particles are ground to flour using smooth
REDUCTION ROLLS.
After each grinding, flour is removed by sieving in a plansifter and
overtailings of the sieves are sent to subsequent reduction rolls.
Wheat Flour Milling

10. The number of reduction stages depends on the flour yield
required but in recent years, the number of stages has gradually
been reduced by the use of impact equipment (flake disruptors,
entoleters).
After the final reduction roll, any remaining fine bran, endosperm
and germ is removed as POLLARD.
Germ is normally flattened on the reduction rolls and, in certain
mills, separated by sieving.
The amount separated is generally less than 2%.
Bran and pollard are sold as animal feeds, although bran and
germ are also packaged separately for human consumption.
Flour Milling

11. EXTRACTION RATE
The number of parts by weight of flour that is produced from one hundred
parts of wheat is termed the FLOUR YIELD or EXTRACTION RATE.
This figure is used as an index of the overall efficiency of a flour milling
system.
In practice, the limit of white flour extraction has been 75-79%;
Further they increases in the extraction rate lead to darker flour colour and
higher ash and fibre contents which adversely affect the breads baked from them.
Milling to produce white flour results in the removal of varying amounts of
bran, pollard and germ which together constitute 12-15% of the grain by weight.
The national average extraction rate has been reported as 75.8% with a range
of 69-80% depending on the efficiency of the mill.

12. DISTRIBUTION OF NUTRIENTS DURING MILLING
 Wheat flour is an excellent source of complex carbohydrates.
 Other than gluten flour, all types of wheat flour derive at least 80
percent of their calories from carbohydrates.
 Depending on the flour type, the percent of calories from protein
ranges from 9 to 15 percent, except from gluten, which has 45
percent protein content.
Flour, comprising about 75-78% of the total mill products, generally
contains 90-95% of the grains protein, 50% of the thiamin (vitamin
B1), and 30-60% of the minerals.
Bran and pollard contain most of the grains fiber and a variable
amount of the vitamins and minerals.

13. Types of wheat Flour
1. Hard wheat flour: including hard white, hard red winter,
and hard red spring wheat have a high protein content
(ranging from 10 to 14 percent), which means the gluten
forming capacity is also higher, suitable for baking yeast
breads and similar products.
2. Soft wheat flour: include soft white and soft red winter,
which are both used for products, such as cakes, cookies.
The protein content of soft wheat varieties, such as cake
and pastry flour, usually ranges from 6 to 10 percent.
3. Durum wheat flour : is the hardest wheat grown. It is
used almost exclusively for making pasta and is most often
ground into a granular flour with a light yellow color known
as semolina,

14. Classifications of wheat flour based on gluten content
and purposes of use
1. All-Purpose Flour: All-purpose flour is formulated to have
a medium gluten content of around 12 percent or so.
2. Bread flour is a strong flour, meaning that it has a
relatively high gluten content — usually around 13 to 14
percent.
3. Cake flour is made from soft wheat and has a lower
gluten content — around 7 to 9 percent. Its grains are
visibly finer than bread flour, and it is much whiter in color.
Its fine, soft texture makes it preferable for tender cakes
and pastries

15. 4. Pastry flour is slightly stronger than cake flour, at
around 9 to 10 percent gluten.
It can be used for biscuits, muffins, cookies, pie doughs
and softer yeast doughs.
It has a slightly more off-white color than cake flour.

16. NON-WHEAT FLOURS
 Types of Flour Ground from Corn
Several varieties of corn are used to produce different types
of corn flour. The degree in which the corn is milled and
processed also determines the type of flour that is produced.
 Corn Flour
A type of flour milled from dried kernels of yellow corn. Corn
flour is very useful for gluten-free quick breads.
Because corn flour contains no gluten, it must be blended
with wheat flour when preparing yeasted breads.

17. Types of Flour Ground from Rice
 Rice flour is produced from uncooked rice that has been
ground into a powder ranging from course to very fine. Rice
ground to a course texture is often used in baked items such
as cookies and cakes.
 Standard rice flour is available in brown or white varieties.
Brown Rice Flour
 Brown rice flour is a type of flour made from rice kernels
that have been processed to remove the outer hulls, but not
the nutritious bran layers covering the kernel.
 When the kernels are ground into flour, the resulting color is
only a shade darker than flour milled from polished rice and
the texture is not quite as smooth.

18. White Rice Flour
White rice flour is a type of flour produced from
grinding polished rice (the bran and germ have been
removed) into a powder.
White rice flour can be used as a thickening agent for
sauces and puddings.
It is also very popular for the preparation of a variety of
Asian noodles.
It is used in some baked goods, such as cakes,
cookies

19. Types of Flour Ground from Rye
 Rye flour is produced from grinding the grains of rye into a
powder.
 Like most other types of flour produced from grains, rye
flour may be ground into varying degrees of fineness ranging
from course to very fine.
 It also is available in light, medium, and dark varieties
according to the quantity of bran included in the flour.
 The type of protein necessary for gluten formation is lower
in rye than wheat, but it is higher than in most other grains.
 Rye flour is often combined with wheat flour when baking
risen breads.

20. Light Rye Flour
During the milling process, the bran is removed from the rye
to produce light rye flour, which is a lightly colored and very
starchy version of rye flour. It is often used for making crusty
black breads.
Medium Rye Flour
Medium rye flour contains some bran, but not as much as
darker versions of rye flour. It is widely used in a variety of rye
breads and other baked goods.
Dark Rye Flour
Dark rye flour is produced from the whole grain minus the
husk. The bran and the germ are retained, which are full of
nutrients.

21. Types of Non-Wheat Flour Ground from Other Grains
Barley Flour
Barley flour is usually produced from barley, which
refers to barley that has been polished to remove the
husk and the bran.
After the malting process has removed the sugar and
starch, the remaining barley (known as malted barley
flour), is steam dried, milled, and sifted to provide the
finished flour product.

22. Oat Flour
Oat flour is produced from hulled and cleaned oats. It is
also ground from rolled oats or oatmeal. Oat flour adds
texture and a rich nutlike flavor to breads and other
baked goods
Seven-Grain Flour or composite flour:
Seven-grain flour is a commercially blended flour
mixture of seven ground grains consisting of wheat, rye,
corn, oats, barley, millet, and flax (or triticale). Usually
used for the manufacturing of baked products.

23. Sorghum Flour
Sorghum, which has a sweet, nutty flavor, is often milled
into flour, but it lacks gluten, so it isn't suitable for making
yeast breads.
Some other non wheat flours are:
buckwheat flour , casava flour, potato flour, chapati
flour , chickpea flour