What is the factors affecting the whiteness of flour?

As the main staple food and food processing raw material in the world, whiteness is one of the important indicators that influence the quality of its evaluation. The factors affecting the whiteness of flour are multifaceted. As a professional factory of wheat flour mills, Hongdefa had the following analysis of factors affecting flour whiteness from a professional perspective.


1. wheat

1. Influence of raw materials

In terms of raw materials, the softness and hardness of the wheat, the color and the oldness, and whether it is hot during the storage process, and insects, can affect the whiteness of the wheat flour;

The endosperm of durum wheat contains more carotene, the color of endosperm is milky yellow, so the processed flour is darker than soft wheat. In the process of milling, a small amount of wheat bran is inevitably broken into bran stars and mixed into flour. Because the white wheat bran is light, it is not obvious when mixed into the flour, so the flour processed by white wheat under the same conditions is white;

The cortex of old wheat and heated wheat will become more breakable, and it is easy to be broken, the flour has more bran stars and darker color;

The newly harvested wheat has higher physiological activity, loose structure and poor quality stability,so the produced flour is pink and dark;

Moth wheat contains a small amount of eggs and excreta. When grinding flour, it is easy to make the flour dark because of its hormone and other reaction;

When wheat has more scab grains and black embryo wheat, the flour produced is poorer in color;

Organic impurities in raw grains also affect the flour color, such as barley, which easily causes the flour to turn green. In addition, different wheat varieties and origins, different mineral and nitrogen contents in the soil of wheat growth also affect the whiteness of wheat.

Different kinds of wheat

different kinds of wheat

Different kind of wheat flour in different colors

3.different kinds of wheat flour in different colors

2. Quality control effect of milled wheat

In the process of wheat processing, it is usually required that the dust mustard impurities in the milled wheat should not exceed 0.2%, of which the sand and stone should not exceed 0.015%, and the grain impurities should not exceed 0.5%. There are no magnetic metal impurities in the milled wheat, and the grinding water and the time of moistening wheat meet the requirements.

After several routes of screening, beating, suction and stone removal, the impurities entrained and surface impurities of wheat can be removed mostly. However, in the later conveying process of bucket elevator, screw conveyor and chute, the friction between wheat grain and wheat grain, wheat grain and equipment will regenerate some wheat fur and wheat skin. In addition, the dust remaining in wheat skin, wheat germ and wheat ditch, which is torn by wheat beater, will also fall off, forming new entrainment impurities affecting the flour color.

Cleaning machines

4.cleaning machines

Hongdefa’s cleaning process is divided into wet cleaning and dry cleaning to ensure that impurities can be cleaned up very cleanly.

Wet way cleaning is to remove stubborn impurities by washing the wheat after several routes of screening, beating, suction, stone removal and other comprehensive cleaning.
Dry way cleaning is that the wheat will have second time screening, beating, suction, stone removal and other comprehensive cleaning.

Washing machine

5.washing machine

To remove the stubborn impurities after the fist time cleaning and moisture.

Dry way cleaning system

6. dry way cleaning system

Wet cleaning saves equipment investment, and its disadvantage is large water consumption and waste water can not be reused, resulting in a large amount of water pollution. Despite the large investment in equipment, dry cleaning saves water resources and does not produce waste water pollution.

Customers can flexibly choose cleaning methods according to local requirements.

In addition, the control of water and time of wheat moistening will also have a great impact on flour color. Because proper watering and moistening can weaken the binding force between wheat cortex and endosperm and enhance the toughness of the cortex. During the subsequent grinding process, the endosperm is easy to peel off the cortex and the cortex is not easy to break up, thus reducing the content of bran in the flour and improving the flour pink. On the contrary, if the water content and moistening time are not properly controlled, the flour color will be worse.

3. Flour system Design and Operation Regulation Effect

The length of the flour system design has a greater impact on flour color. For example, the shorter the design of flour road, in order to ensure the yield of powder, it is necessary to enhance the grinding strength of the mill. The increase of grinding strength will increase the percent of crushing of wheat skin, increase the quantity of bran in the powder, and make the flour color worse. Compared with the shorter powder road, the longer powder route has more grinding times, so it can be lightly ground and fine grinding, thus reducing the crushing of wheat skin. Opportunities to improve flour whiteness.

Wheat flour milling system

7. wheat flour milling system

But even in the long flour mill process, the unreasonable allocation of equipment in each system will affect the flour color, such as: the contact length of the front and middle road bran grinding roll is not enough, the production process may not be milled properly, resulting in a tight rolling distance, making the bran not easy to maintain integrity, the flour is easy to mix with bran, thus making the flour color worse; and also, the front and middle road flour grinding roll, If the contact length is not enough, the flour with low ash content will not be put forward in time and in sufficient quantity in front of the mill, will be pushed to the middle and back of the mill for repeated grinding, which will also make the flour color worse.

Advanced flour milling technology also needs high level of professional operation skills. If flour milling operators do not fully understand the design essentials of modern flour milling technology and grasp the key points of operation in flour milling process, such as: front skin grinding scraping rate, front core grinding rate, slag grinding system and the technological effect of flour cleaner, etc., flour color will be affected. There is a famous saying in flour milling industry. The proverb “three-point process, seven-point operation” fully reflects the importance of the control effect of flour milling system.

Hongdefa has more than 30 years experience in wheat flour milling and design. There are many more than 35 years of experience engineers to make the design equipment and control quality.

Hongdefa professional engineer team 

8.Hongdefa Professinal engineer Team

Hongdefa provides overseas installation and commissioning training services. According to the customer’s requirements, engineers can training in the customer’s factory for more than 6 months or even a year until the customer’s workers can operate the equipment skillfully and solve the daily problems afterwards.

Engineer Mr Huang in Zimbabwe client factory

9. Engineer Mr Huang in Zimbabwe

Ethiopia Branch office people with 40T wheat flour client and workers


4. Other impacts

Whether wheat germ is ground into flour, grinding temperature, flour yield, flour coarseness and fineness, storage time and adding whitening agent can also affect flour whiteness. Under the same conditions, wheat germ is ground into flour, grinding temperature is too high, flour yield is high, flour particle size is coarse, storage time is short, without whitening agent, the wheat flour whiteness is much poor.

Micro dosser for the whitening agent

11. Micro Dosser

Hongdefa Machinery supply you best solution for the wheat flour mill processing. And have installed many big capacity wheat flour mills in different countries.

Ethiopia 500T/24H wheat flour milling machine;

Afghanistan 300T/24H wheat flour mill machine;

Egypt 200T/24H wheat flour milling machine;

Brazil 200T/24H wheat flour mill machine;

China 120T/24H wheat flour mills


Afghanistan 300T/24H wheat flour mill

12. Afghanistan 300T flour mill

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