Flour is a powder which is made by grinding cereal grains or other seeds or roots.

It is the main
ingredient of bread, which is a staple food for many cultures. Wheat flour is one of the most
important ingredients in Oceanic, European, North American, Middle Eastern, Indian and North
African cultures, and is the defining ingredient in most of their styles of bread and pastries.

Major Categories of Flour

1.Unbleached Flour
Unbleached flour is simply flour that has not undergone bleaching and therefore does not have the
colour of “white” flour.
2.Bleached Flour
“Refined flour” has had the germ and bran removed and is typically referred to as “white flour”.
“Bleached flour” is any refined flour with a whitening agent added.
3.Plain Flour
Flour that does not have a leavening agent is called plain or all-purpose flour. It is appropriate for
most bread and pizza bases. Some biscuits are also prepared using this type of flour. Bread flour is
high in gluten protein, with 12.5-14% protein compared to 10-12% protein in all-purpose flour. The
increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation
process, resulting in a stronger rise.
4.Self Rising Flour
Leavening agents are used with some varieties of flour, especially those with significant gluten
content, to produce lighter and softer baked products by embedding small gas bubbles. Self-rising (or
self-raising) flour is sold premixed with chemical leavening agents. The added ingredients are evenly
distributed throughout the flour which aids a consistent rise in baked goods. This flour is generally
used for preparing scones, biscuits, muffins, etc.
5.Enriched Flour
During the process of making flour nutrients are lost. Some of these nutrients are replaced during
refining and the result is “enriched flour”.

Methods to judge quality of Flour

Flour Colour
A very simple way to determine colour differences in different batches of flour is to look at the colour
of different types of flour under a sheet of glass. This can be done with more than one flour at a
time. This method not only facilitates a comparison of the whiteness of different flours but also
allows for an inspection for impurities. The flour should be of “perfectly regular consistency and not
contain any specks”. This obviously does not pertain to mixed grain or to other than white flours.
Several methods exist for the measurement of colour, all of which relate to the quantity of reflected
or absorbed light.
Texture and Feel
The texture and size of granulation plays an important role in kneading and also determines the
speed at which the dough rises. In general, bread flour is slightly coarse and falls apart when pressed
into a lump. Pastry flour is smooth and fine and can be squeezed into a lump. Cake flour is smooth
and fine, can be squeezed into a lump, and stays in a lump more solidly when pressed.
Absorption Ability
Absorption measures the amount of water that can be absorbed by a given quantity of flour. In bread
making, it is usually preferable to have flour that can absorb a large amount of water. Measurements
of absorption are done to determine the amount of water the dough can absorb, which in turn
indicates dough yield and shelf life. Optimum absorption represents the maximum amount of water,
as a percent of the flour weight that will produce a high yield of bread during the baking process.
Flour Protein
Traditionally flour protein has been the main parameter used to judge flour quality and strength.
Today we know that not all wheat protein is created alike. Wheat “protein” or Albumen is composed
of four types of protein: gliadin, glutenin, albumin and globulin. Gliadin and glutenin comprise
roughly 85% of the Albumen, and are the gluten-forming components. Albumin and globulin are
water soluble, and thus don’t add to the strength of the flour. The percentage of protein (Albumen)
only tells us the amount of protein, and is only a hint as to the real character of the flour. This figure
does not tell us anything about the type, or quality of protein. The farinograph test gives us more
valuable information about the “quality” of the protein; and thus how it will perform in the bakery.
Flour Moisture
The level of moisture in flour is important mainly f or the issue of storage. When the moisture level
exceeds 16 % the shelf life of the flour is greatly reduced. Generally, the moisture will be 14-15%,
which when stored in appropriate conditions (relatively cool, dry and aerated) allows for plenty of
shelf life. There is a correlation between moisture content and water absorption but can be
counteracted by starch damage.
Flour Ash
The ash content of the flour is determined by incinerating a sample of flour. The minerals naturally
present in the flour do not burn and remain as ash. The weight of the ash is then compared to the
original sample. The ash content tells us something about the extraction of the flour. In the
endosperm of the wheat kernel, the mineral content increases from the centre outwards. The area of
the endosperm nearest the aleurone and bran layers has the highest mineral content. Higher ash
contents indicate higher extraction. Most flours will have an ash content below 0.6%, patent flours
can go as low as 0.35%
Falling Number
The falling number test determines the amylase activity of a flour sample. The amylase enzymes are
used to break down the starch in flour to release sugar ready for fermentation. The test entails
heating measured amounts of water and flour in a special test tube. The tube is placed in a boiling
water bath and agitated with a plunger for 55 seconds to allow the sample to gelatinise. Then the
plunger is released at the top of its cycle on the surface of the sample, the time that it takes the
plunger to sink through the gelatinised starch to the bottom of the tube is recorded. The total time in
seconds (including the original 55 seconds) is recorded as the “falling number”. Therefore the
minimum number is 55 and some flours can push into the high 400’s and beyond.
Depending on the alpha-amylase activity, the degradation of the starch paste will vary. The higher
the alpha-amylase activity, the lower the number, and vice versa. In Australian and Canadian wheats,
typically the falling number has to be adjusted (reduced) in the flour through the addition of diastatic
malt, or fungal amylase for use in the Bakery. Generally the baker will find that fermentation
progresses more rapidly as falling numbers become lower.
Farinograph
The “Brabender Farinograph” is one of the most common flour testing machines in use today. The
farinograph produces a graph that represents the force required to turn two mixing arms in a small
mixing chamber with dough at an adjusted hydration. On the graph each vertical line represents
thirty seconds
MTI
Mixing tolerance index is the difference in BU, from the top of the curve at the peak to the top of the
curve measured at five minutes after the peak. Higher MTI numbers indicate greater mixing
tolerance.
Starch Damage
Inherent characteristics of the wheat, along with the physical effects of milling determine the level of
starch damage. The process of wheat milling damages a portion of the starch granules. This tendency
is amplified as the hardness of the wheat increases. Because of this, the starch damage is of
particular concern here in New Zealand. Starch damage increases the amount of fermentable
carbohydrate as well as the absorption of the flour. Normally starch granules absorb one-third their
weight in water, when damaged that increases to 2-3 times their weight. Damaged starch granules
are very susceptible to attack by alpha-amylase enzymes.
The combination of high levels of fermentable carbohydrate, and water, (and thus rapid enzymatic
activity) make conditions optimal for more active fermentation as the damaged starch levels
increase. Also, though flour with high starch damage figures absorbs a lot of water, once the amylase
enzymes do their work, the dough becomes slack. Balance, as always, is key. Too much starch
damage and the dough tends to be slack and over-fermented; too little and the fermentation stalls
after the immediately available sugars are consumed.
One should expect to see starch damage at 6-9% for winter wheat, and 7-10% for spring. Damaged
starch significantly affects both Farinograph water absorption, and dough extensibility and resistance
(Alveograph).
Extensograph
Produced by Chopin, the Alveograph is an instrument that gives valuable rheological information
about a dough sample by measuring the pressures attained during the inflation of a dough sample
into a bubble. Because the test expands a dough sample in a biaxial plane, similar to the way dough
cells expand in actual bread dough, this test is highly regarded. This test is traditionally used as a
standard in countries that have historical or cultural links to France but is used elsewhere in the
world as a supplementary test for evaluation or verification purposes.

Types of Wheat
Wheat is categorised according to its hardness(hard/soft), colour (red/white) and shape of its
kernel.

 Hard Red Winter

 Hard Red Spring

 Soft Red Winter

 Durum

 Hard White Wheat

 Soft White Wheat

THE DIFFERENT PURPOSES OF DIFFERENT TYPES OF WHEAT

The protein content of the wheat is what primarily determines what the wheat will be used
for and the greater the protein, the greater the elasticity of the dough will be.

 Hard red winter and hard red spring contain the highest percentages of protein are most
often used in goods requiring size, like breads and rolls.

 Hard white and soft white contain the lowest percentages of protein and best suited for
baked goods like cakes, cookies, crackers, pastries and muffins.

The colour of the wheat plays a part too and as you may have already guessed, red wheat is darker
than white wheat. Red wheat also has a stronger, more bitter flavour than white.

 Soft red winter is often used in blatantly obvious brown crackers and flat breads. These are
often marketed as “whole grain” crackers and such.

 Soft white is used in goods when manufactures want the item to look and taste “white,” but
be able to claim as healthy with wheat. One example of this are muffins “made with white
wheat.”

 Durum is a variety of wheat that has a higher protein and gluten content than other kinds of
wheat and that is most often found in pasta.

Wheat milling process:

Flour is a finely ground powder prepared from grain or other starchy plant foods and used in baking.
Although flour can be made from a wide variety of plants, the vast majority is made from wheat. The
earliest methods used for producing flour all involved grinding grain between stones.
A typical Diagram Showing Processing of wheat
Grading the wheat

Wheat is received at the flour mill and inspected. Samples of wheat are taken for physical and
chemical analysis. The wheat is graded based on several factors, the most important of which is the
protein content. The wheat is stored in silos with wheat of the same grade until needed for milling.

Primary processing of wheat

Two methods of milling can be used for wheat, stone grinding and roller milling. Stone grinding is the
traditional method of grinding the wheat between two large, heavy circular stones, where the top
stone revolves on the lower one. The stones are grooved to assist in the grinding process. The final
product is stone-ground wholemeal (or whole wheat) flour. Roller milling is the most common
method of milling wheat. Roller milling involves the wheat being passed through a series of steel
rollers, each rotating at a different speed. These crush the grain and separate the outer bran layer
from the inner endosperm. The endosperm is passed through several more rollers, the wheat germ is
removed and the final product is plain (white, refined) flour.

Processing the flour

Small amounts of bleaching agents and oxidizing agents are usually added to the flour after milling.
Vitamins and minerals are added as required by law to produce enriched flour. Leavening agents and
salt are added to produce self-rising flour. The flour is matured for one or two months.