Flour Milling Process

Crown Flour Mills is constantly striving to secure both production efficiency and product quality by making the best possible use of raw material. 

Wheat CleaningBefore wheat can be grounded into flour it must be free of foreign material such as stones, dust and weed seeds. This requires several different cleaning processes.The wheat next passes through an aspirator that works like a vacuum cleaner sucking up strange substances which is lighter than the wheat and removing it.

Wheat GradingSamples 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 and quality. A number of grades are usually then blended together to produce the desired type of flour. 

Wheat Tempering The tempering of grains prior to milling is essential since the milling yield is highly dependent on the moisture content of the grain going into the first break of the mill: Preparing the wheat for grinding

The cleaned wheat is conditioned with water using highly sophisticated equipment that measure:- Test weight;- Moisture;- Temperature;- Hardness

Grinding the wheat• Wheat of different grades and moistures is blended together to obtain a batch of wheat with the characteristics necessary to make the kind of flour being manufactured. 

• The wheat moves between two large metal rollers known as breaker rolls. These rollers crack open the grains of wheat and begin to separate the interior of the wheat from the outer layer of bran. 

• The product of the breaker rolls passes through metal sieves to separate it into three categories:o The finest material resembles coarse flour and is known as middlings or farina. 

o Larger pieces of the interior are known as semolina. 

o The third category consists of pieces of the interior which are still attached to the bran. By sifting, separating, and regrinding the flour, several different grades of flour are produced at the same time. These are combined as needed to produce the desired final products. 

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. Dough made from wheat flour

is particularly well suited to baking bread because it contains a large

amount of gluten, a substance composed of strong, elastic proteins. The

gluten forms a network throughout the dough, trapping the gases which are

formed by yeast, baking powder, or other leavening agents. This causes the

dough to rise, resulting in light, soft bread.

Flour has been made since prehistoric times. The earliest methods used for

producing flour all involved grinding grain between stones. These methods

included the mortar and pestle (a stone club striking grain held in a stone

bowl), the saddlestone (a cylindrical stone rolling against grain held in a

stone bowl), and the quern (a horizontal, disk-shaped stone spinning on top

of grain held on another horizontal stone). These devices were all operated

by hand.

The millstone, a later development, consisted of one vertical, disk-shaped

stone rolling on grain sitting on a horizontal, disk-shaped stone. Millstones

were first operated by human or animal power. The ancient Romans used

waterwheels to power millstones. Windmills were also used to power

millstones in Europe by the twelfth century.

The first mill in the North American colonies appeared in Boston in 1632

and was powered by wind. Most later mills in the region used water. The

availability of water power and water transportation made Philadelphia,

Pennsylvania, the center of milling in the newly independent United States.

The first fully automatic mill was built near Philadelphia by Oliver Evans in

1784. During the next century, the center of milling moved as railroads

developed, eventually settling in Minneapolis, Minnesota. During the

nineteenth century numerous improvements were made in mill technology.

In 1865, Edmund La Croix introduced the first middlings purifier in

Hastings, Minnesota. This device consisted of a vibrating screen through

which air was blown to remove bran from ground wheat. The resulting

product, known as middlings or farina, could be further ground into high-

quality flour. In 1878, the first important roller mill was used in

Minneapolis, Minnesota. This new type of mill used metal rollers, rather

than millstones, to grind wheat. Roller mills were less expensive, more

efficient, more uniform, and cleaner than millstones. Modern versions of

middlings purifiers and roller mills are still used to make flour today.

Raw Materials

Although most flour is made from wheat, it can also be made from other

starchy plant foods. These include barley, buckwheat, corn, lima beans,

oats, peanuts, potatoes, soybeans, rice, and rye. Many varieties of wheat

exist for use in making flour. In general, wheat is either hard (containing

11-18% protein) or soft (containing 8-11% protein). Flour intended to be

used to bake bread is made from hard wheat. The high percentage of

protein in hard wheat means the dough will have more gluten, allowing it to

rise more than soft wheat flour. Flour intended to be used to bake cakes and

pastry is made from soft wheat. All-purpose flour is made from a blend of

soft and hard wheat. Durum wheat is a special variety of hard wheat, which

is used to make a kind of flour called semolina. Semolina is most often used

to make pasta.

Flour usually contains a small amount of additives. Bleaching agents such

as benzoyl peroxide are added to make the flour more white. Oxidizing

agents (also known as improvers) such as potassium bromate, chlorine

dioxide, and azodicarbonamide are added to enhance the baking quality of

the flour. These agents are added in a few parts per million. Self-rising flour

contains salt and a leavening agent such as calcium phosphate. It is used to

make baked goods without the need to add yeast or baking powder. Most

states require flour to contain added vitamins and minerals to replace those

lost during milling. The most important of these are iron and the B vitamins,

especially thiamin, riboflavin, and niacin.

The Manufacturing Process

Grading the wheat

1 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.

Purifying the wheat

An illustration from The Young Millwright and Miller's Guide, depicting the

processes of an automated grain mill.

(From the collections of Henry Ford Museum & Greenfield Village.)

In 1795, an American engineer published a book called The Young

Millwright and Miller's Guide. In the book, simple theories are transformed

into a set of mechanical devices that form a flour mill. At the back of the

book is a drawing, illustrating how these devices make a continuous

production line in which the human hand is eliminated from the beginning

of the process to the end of production. The author of this book was Oliver

Evans, himself the son of a miller. He and his brothers ran their own mill,

developed the systems, and perfected the operations that led to the

automated grain mill.

Today, Evans is considered one of America's most ambitious mechanical

innovators. He used his understanding of the way in which water turned a

mill wheel and developed it into a viable grain-milling system.

Most important was the fact that his system contained the idea of the

integrated and automated factory. When a machine substitutes human

intervention, the problems of the fully automated assembly line are solved.

This concept was not fully applied until the 1920s by Henry Ford, who was

able to develop a successful, operational assembly line. Ford had the

advantage of living at the end of the machine age, but Oliver Evans was the

first to present the concept of automation before it was even possible.

Henry Prebys

2 Before wheat can be ground into flour it must be free of foreign

matter. This requires several different cleaning processes. At each

step of purification the wheat is inspected and purified again if

necessary.

3 The first device used to purify wheat is known as a separator. This

machine passes the wheat over a series of metal screens. The wheat

and other small particles pass through the screen while large objects

such as sticks and rocks are removed.

4 The wheat next passes through an aspirator. This device works like

a vacuum cleaner. The aspirator sucks up foreign matter which is

lighter than the wheat and removes it.

5 Other foreign objects are removed in various ways. One device,

known as a disk separator, moves the wheat over a series of disks

with indentations that collect objects the size of a grain of wheat.

Smaller or larger objects pass over the disks and are removed.

6 Another device, known as a spiral seed separator, makes use of the

fact that wheat grains are oval while most other plant seeds are

round. The wheat moves down a rapidly spinning cylinder. The oval

wheat grains tend to move toward the center of the cylinder while the

round seeds tend to move to the sides of the cylinder, where they are

removed.

7 Other methods used to purify wheat include magnets to remove

small pieces of metal, scourers to scrape off dirt and hair, and

electronic color sorting machines to remove material which is not the

same color as wheat.

Preparing the wheat for grinding

8 The purified wheat is washed in warm water and placed in a

centrifuge to be spun dry. During this process any remaining foreign

matter is washed away.

9 The moisture content of the wheat must now be controlled to allow

the outer

layer of bran to be removed efficiently during grinding. This process is

known as conditioning or tempering. Several methods exist of

controlling the amount of water present within each grain of wheat.

Usually this involves adding, rather than removing, moisture.

10 Cold conditioning involves soaking the wheat in cold water for one

to three days. Warm conditioning involves soaking the wheat in water

at a temperature of 115°F (46°C) for 60-90 minutes and letting it rest

for one day. Hot conditioning involves soaking the wheat in water at a

temperature of 140°F (60°C) for a short period of time. This method is

difficult to control and is rarely used. Instead of water, wheat may

also be conditioned with steam at various temperatures and pressures

for various amounts of time. If conditioning results in too much

moisture, or if the wheat happens to be too moist after purification,

water can be removed by vacuum dryers.

Grinding the wheat

11 Wheat of different grades and moistures is blended together to

obtain a batch of wheat with the characteristics necessary to make

the kind of flour being manufactured. At this point, the wheat may be

processed in an Entoleter, a trade name for a device with rapidly

spinning disks which hurl the grains of wheat against small metal

pins. Those grains which crack are considered to be unsuitable for

grinding and are removed.

12 The wheat moves between two large metal rollers known as

breaker rolls. These rollers are of two different sizes and move at

different speeds. They also contain spiral grooves which crack open

the grains of wheat and begin to separate the interior of the wheat

from the outer layer of bran. The product of the breaker rolls passes

through metal sieves to separate it into three categories. The finest

material resembles a coarse flour and is known as middlings or farina.

Larger pieces of the interior are known as semolina. The third

category consists of pieces of the interior which are still attached to

the bran. The middlings move to the middlings purifier and the other

materials move to another pair of breaker rolls. About four or five

pairs of breaker rolls are needed to produce the necessary amount of

middlings.

13 The middlings purifier moves the middlings over a vibrating

screen. Air is blown up through the screen to remove the lighter

pieces of bran which are mixed with the middlings. The middlings

pass through the screen to be more finely ground.

14 Middlings are ground into flour by pairs of large, smooth metal

rollers. Each time the flour is ground it passes through sieves to

separate it into flours of different fineness. These sieves are made of

metal wire when the flour is coarse, but are made of nylon or silk

when the flour is fine. By sifting, separating, and regrinding the flour,

several different grades of flour are produced at the same time. These

are combined as needed to produce the desired final products.

Processing the flour

15 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.

16 The flour is packed into cloth bags which hold 2, 5, 10, 25, 50, or

100 lb (About 0.9, 2.3, 4.5, 11.3, 22.7, or 45.4 kg). For large-scale

consumers, it may be packed in metal tote bins which hold 3000 lb

(1361 kg), truck bins which hold 45,000 lb (20,412 kg), or railroad

bins which hold 100,000 lb (45,360 kg).

Quality Control

The quality control of flour begins when the wheat is received at the flour

mill. The wheat is tested for its protein content and for its ash content. The

ash content is the portion which remains after burning and consists of

various minerals.

During each step of the purification process, several samples are taken to

ensure that no foreign matter ends up in the flour. Since flour is intended

for human consumption, all the equipment used in milling is thoroughly

cleaned and sterilized by hot steam and ultraviolet light. The equipment is

also treated with antibacterial agents and antifungal agents to kill any

microscopic organisms which might contaminate it. Hot water is used to

remove any remaining traces of these agents.

The final product of milling is tested for baking in test kitchens to ensure

that it is suitable for the uses for which it is intended. The vitamin and

mineral content is measured in order to comply with government standards.

The exact amount of additives present is measured to ensure accurate

labeling.

Byproducts/Waste

A kernel of wheat consists of three parts, two of which can be considered

byproducts of the milling process. The bran is the outer covering of the

kernel and is high in fiber. The germ is the innermost portion of the kernel

and is high in fat. The endosperm makes up the bulk of the kernel and is

high in proteins and carbohydrates. Whole wheat flour uses all parts of the

kernel, but white flour uses only the endosperm.

Bran removed during milling is often added to breakfast cereals and baked

goods as a source of fiber. It is also widely used in animal feeds. Wheat

germ removed during milling is often used as a food supplement or as a

source of edible vegetable oil. Like bran, it is also used in animal feeds.

Read more: http://www.madehow.com/Volume-3/Flour.html#b#ixzz2LjsdwQ9r

PROJECT PROFILE ON MINI FLOUR MILL

PRODUCT : WHEAT FLOUR (Atta),

SOOJI/RAWA

WHEAT FLOUR (Maida),

BRAN

PRODUCT CODE : 204109000 (Wheat Flour)

204111003 (Sooji /Rawa)

204108004 (Maida)

QUALITY STANDARD. : The Product may be manufactured as per

‘AGMARK’ Specification. The BIS have also laid

down Specification for the Products :

IS :1155 – 1968 (Wheat Atta).

IS : 1009 - 1979 (Maida)

IS : 1010 – 1968 (Sooji/Rawa)

PRODUCTION CAPACITY (P.A.) : Item Qnty. (MT) Value (Rs.)

Atta 1800 2,43,00,000

Maida 4500 6,52,50,000

:

:

Sooji 1080 1,56,60,000

Bran 1620 1,53,90,000

MONTH & YEAR OF

PREPARATION

: March , 2011

PREPARED BY : MSME-Development Institute,

11-A,IDC,Karnal..2

A. INTRODUCTION.

There are 812 roller flour mills in our country producing approximate 25 million tonnes, of

milled cereal products worth Rs. 1200 crores. Flour Mills can be installed with minimum capacity of 30

TPD of raw material crushing capacity per day to maximum 1000 TPD. The capacity suggested in this

report is for mini flour mill i.e. 30 tonnes of raw material crushing capacity per day. As per CII mckinsey

survey it is estimated that by 2005 the market for branded Atta has grown to Rs. 15000 crore.

B. MARKET POTENTIAL.

Whole wheat flour is used in making Chapaties, Puries, Parotha and other

roasted cereal based products. Wheat flour or Maida is a basic raw material for making

Bread, Biscuits Cakes and other bakery products. Sooji / Rava is used in many

sweetmeat products. Bran separated on milling is used as cattle feed. The products

sold under brand names are very few. The concept for branded cereal flour products is

now increasing. The big giants like Hindustan Lever, NEPC Agro, Nirma etc. have

jumped in to this lucrative industry.

C. BASIS AND PRESUMPTIONS: -

1. It is presumed that the unit will run three shift per day and 300 working days per

annum.

2. The following extraction rates are presumed :

Maida 50 %

Sooji 12 %

Atta 20 %

Bran 18 %

Extraction rates are only suggested. Miller can change according to demand,

Wheat quality & climatic conditions.

3. Labour wages have been taken as per market rates.

4. Different varieties of wheat may be blended for producing desired end product.

5. The rate of interest has been taken 14% on an average both for fixed investment

and working capital.

6. The rates quoted in respect of Machinery/equipment raw materials are those

prevailing at the time of preparation of report and are likely to vary from place to

place and supplier to supplier and necessary changes are to be made as and

when required.

D. IMPLEMENTATION SCHEDULE.

The approximate time required for various activities is given below. However, it may vary from

place to place depending upon the local circumstances: -3

i. Selection of site. 1 Month

ii. SSI Registration . 7 days

iii. Project Report Preparation. 1 Month

iv. Availability of Finance 2 Month

v. Machinery Procurement, Erection,

Commissioning & Trial Run, etc.

8

th

months

onward.

E. TECHNICAL ASPECTS.

1. Production Details & Process of Manufacture

Wheat is first cleaned thoroughly to remove dust, stone and other foreign matters clean

wheat is tempered before grinding by treating with water so that the bran is separated from the

endosperm. The tempered wheat is crushed between corrugated rollers (Break rolls). The first

break rolls are set relatively far apart to grind the wheat lightly, while successive break yield

finer and finer products. The first break is separated by sieving or bolting in to very fine particles

(flour), intermediate particles (middlings) and coarse particles (stock). The stock is then sent to

second break rolls. This process may continue through 5 to 6 breaks. The stock contains pieces

of endosperm and bran and the stock from the last break is principally bran. The middlings

contain endosperm, bran and germ which are then successively classified and some of the bran

removed are sent to reduction rollers. These are smooth rollers, but like the break rolls they are

graduated so that successive reduction becomes finer and finer. After each reduction, sifters

separate the flour, middling and stock, this process is continued until most of the endosperm

has been removed as flour and most of the bran has been separated in the sifters.

2. Power requirement of the unit is 300 HP.

3. There are no pollution problems for unit except dust which may damage the plant and

machinery and adversely affect the health of workers also, for this cyclones may be used to

separate dust.

4. The Miller should be made aware about the energy requirement of the milling system and for

this selection of motors should be proper.