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The production of flour consists of the following three parts

☆Wheat cleaning and moistening

☆Wheat milling

☆Wheat flour after treatment

1. Wheat Cleaning

(1).Cleaning equipment and working principle

Cleaning equipment is mainly the use of wheat and impurities in the size, weight, shape, gravity, magnetic and other differences to clean up. These devices include the following categories:

Screening equipment: such as roller screen, vibrating screen, plane rotary screen

Scourer Equipment: such as wheat scourer, wheat brush machine, impact machine.

DeStone equipment: such as destoner, the specific gravity grading machine

Selection equipment:Such as disk cylinder separator

Winnowing device: vertical suction duct, circulating air separator.

Magnetic separation equipment: permanent magnetic cylinder

(2).Cleaning process flow

Wheat cleaning including pre-cleaning, raw wheat cleaning, net wheat cleaning
Pre-cleaning process
Raw wheat cleaning process
Net wheat cleaning process
(3)Cleaning requirements

Impurities no more than 0.3%;
Grain impurities not more than 0.5%;
Sandstone no more than 0.015%;
Non magnetic metal;


2. Wheat Moistening

(1)Wheat moistening standard
In order to avoid mildew and germination, the water should be controlled below 12.5%, but it is not good for wheat in this water content. Therefore, before the wheat into the flour, take wheat tempering treatment. In the actual production, the moisture and time should be according to the following rules.
 
Moisture of Wheat: soft wheat14%-15%
Hard wheat 15.5%-16.5%
Hua wheat15%-16%
Moisture Time of wheat:soft wheat in summer 18-24 hours
Soft wheat in winter 24-36 hours
Hard wheat in summer 24-36 hours
Hard wheat in winter:36-48 hours
The control of moisture and time is critical. The moisture content of wheat is too small, the water absorption is not enough in the process of flour milling, and the toughness is not easy to break, which affects the ash color. Too much moisture, will lead to excessive moisture content of finished flour, is not conducive to storage, and because the material is too viscous, prone to clogging in the production process, resulting in instability. Winter wheat moisture need to more fully, time to be longer, so that is conducive to ensuring the quality of flour.

(2)Effect of wheat moistening

Wheat moister is a very important process in the production process of flour, the quality of wheat flour directly affects the quality and stability of production.
Increase the toughness of the cortex, to avoid the impact of the cortex broken flour quality;
Reduce the binding force of cortex and endosperm, make the cortex and endosperm easier to separate;
Reduce the hardness of endosperm, so that the endosperm is easier to be grinded into powder, reduce energy consumption

(3)Factors affecting wheat moistening
Wheat moister temperature
Wheat hardness
Wheat moister

3. Wheat milling
Wheat flour is wheat bran and endosperm and the embryo and endosperm separation, then grinding into powder process. The wheat grain is composed of three parts of endosperm, embryo and oatmeal. Each part by weight percentage: 82 -85% endosperm,  embryos of 2 ~ 3%, 12 ~ 14% oatmeal. Endosperm contains a large number of starch, and contains some of the gluten protein composition, it is the main raw material to make pasta products. Oatmeal containing more fiber, less nutrition, mainly used as feed. Embryo containing protein 25 ~ 33%, fat 6-11%. For wheat and wheat germ mixed with wheat flour will affect the color and baking, and easy to deteriorate during storage, the separation of two and the endosperm, is a necessary step in wheat flour.
(1)Main equipment and working principle of milling

Flour milling mainly equipment is flour mill, high square plansifter, flour cleaning machine

Flour milling machine:Consisting of a pair of grinding rollers with a diameter of 250mm 1000mm, two roller speed is different, one is called slow roll, one is called fast roller, wheat or intermediate particles fall into between two rollers, with a slow roller as the backing, the formation of the fast roller scraping and pressure. The grinding roller of the leather grinding system adopts the roller, which can peel off the role of wheat and the cortex, and the system of the tail of the heart is made of light roller, which is beneficial to rolling.


High square plansifter: The screen body is generally composed of 4-8 screening bins, each sieve bin is equipped with 26-30 layers of sieve surface, the screen surface according to the requirements of different aperture size, you can sort out the bran, slag, fine slag, heart and powder. The screen body is flat and circular motion, the motion diameter is 60-90mm, the speed is 190-280r/min.
Flour cleaning machine:Consists of three layers of sieve surface, from top to bottom, mesh size from large to small. The sieve body is used for reciprocating vibration, and the material can be automatically classified by using the wind force which passes through the sieve mesh evenly, and the bran, the skin particles and the pure wheat heart particles can be separated.

4.Flour after-treatment

Flour milling is an important part of modern flour industry. Including flour bulk transportation, storage, warehouse, flour mixing, addition of modifier, packaging and so on.

After-treatment process