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Oil pretreatment process

August 18, 2021

In the edible oil production process, the entire preparation process from raw materials to extraction of edible oil is collectively referred to as oil pretreatment. Oil pretreatment includes a series of steps such as oil cleaning, shelling, crushing, softening, rolling, puffing, and steaming. Oil pretreatment equipment includes cleaning equipment, shelling machine, crusher, softening pot, embryo rolling machine, puffing machine, steaming and frying pan, etc. After pretreatment, the impurities in the oil are removed, the service life of the oil processing equipment is prolonged, and the internal structure of the oil is changed, which is conducive to the extraction of edible oil. Therefore, oil pretreatment is a key step in the edible oil production process.


Oil pretreatment equipment


The following is the oil pretreatment process:

1. Oil cleaning

Oil cleaning is the general term for the process of removing impurities contained in the oil. In the process of harvesting, transportation, and storage of oil, various impurities may be mixed in. The oil generally contains 1%-6% of impurities, and some up to 10%. According to the characteristics of impurities, we need to adopt different cleaning methods, mainly including screening, winnowing, magnetic separation, stone removal, cleaning "side by side mud", dust removal and other steps. Commonly used cleaning equipment mainly includes vibrating screen, magnetic separator, stone remover and other equipment. After the various oils are cleaned, they must not contain large impurities such as rocks, iron impurities, hemp rope, and Kobresia. The content of total impurities should comply with national standards.

2. Oil peeling

Shelling is mainly suitable for shelled oils, such as peanuts, cottonseeds, sunflower seeds, etc. The oil in the oil is mainly concentrated in the nucleus, and the oil content in the shell is very small. If the oil is made with shells, not only will the oil not be produced, but the oil will be absorbed in the cake and the oil production rate will be reduced. Shelling can speed up the oil yield, speed up the quality of crude oil and cakes, reduce the wear on the equipment, and increase the reasonable production capacity of the equipment. Shelling equipment mainly includes disk shelling machine, knife plate shelling machine, toothed roller shelling machine, shell and kernel separation combined machine, roller shelling machine, etc. According to the technical requirements of oil peeling, choose a suitable peeling machine. 

3. Crushed oil

Using mechanical methods, the process of reducing the particle size of the oil is called crushing. Fragmentation is for oilseeds with large grains, such as soybeans and peanut kernels. After the oil is broken, the surface area increases, which is conducive to the transfer of temperature and moisture during softening, and the softening effect is accelerated. Commonly used crushing equipment includes roller crushers, toothed roller crushers and hammer crushers. Different oils and different process technologies have different requirements for crushing. Our engineers will equip you with suitable crushing equipment according to your oil properties and processing technology.

4. Oil softening

Softening is the process of adjusting the moisture and temperature of the oil, making it soft, increasing the plasticity of the oil, and making the oil meet the conditions of rolling. Softening has the required selectivity to the oil, and different oils have different requirements. Softening is indispensable for oilseeds such as soybeans with low oil content, rapeseeds with low water content, and cottonseeds. If it is not softened, the billet will produce a large amount of powder, which will also bring wear to the equipment. For oil with high oil content, it is generally not softened, otherwise, it will be easy to stick to the surface of the roll when rolling, which will cause difficulty in operation. Our engineers can decide whether the soft chemical section is needed according to the characteristics of the oil. The softening equipment is mainly the drum softening pot. The steaming pan also has a softening effect.

5. Oil billet

Blank rolling is the process of pressing the oil from the granular shape into thin slices by the action of machinery. The sheet material after rolling embryo is called raw embryo. The purpose of embryo rolling is to destroy the cell tissue of the oil, increase the surface area of ​​the oil, and provide convenient conditions for steaming and frying, so that the oil can be separated smoothly during pressing or leaching. Commonly used oil-bearing billet rolling equipment includes in-line billet rolling mills, such as three-roll billet rolling mills, and counter-row billet rolling mills, such as single-roll billet rolling mills. 

6. Oil puffing

The puffing of oil is a process of using puffing equipment to transform the crushed, rolled or whole grain oil into a porous puffed material. After expansion, the oil cell tissue is destroyed, the inside has more porosity, the outer surface has more free oil, the particle size and mechanical strength are increased, the permeability of the solvent to the material layer is greatly changed during leaching, and the leaching speed is increased. , The leaching time is shortened, so the output of the extractor can be increased by 30%-50%. In addition, the puffing process reduces the acid value of the crude oil and speeds up the quality of the leached crude oil. Oil puffing is mainly used in rice bran oil production and soybean oil production. Puffing equipment is mainly a puffing machine.

7. Steamed and fried oil

Oil steaming refers to the process in which the green body undergoes treatment such as wetting, heating, steaming and frying the body to change its internal structure and transform it into a mature body. The purpose of steaming and frying is to fully destroy the oil cells through the action of temperature and moisture, denature protein, accumulate grease, reduce grease viscosity and surface tension, adjust the elasticity and plasticity of the blank, and passivate enzymes to make grease It is more fully prepared and taken out, and the quality of the crude oil is improved. Common oil steaming and frying equipment include layered steaming and frying pan, horizontal steaming and frying pan, cylindrical frying pan and so on.

This is the general process of oil pretreatment. The characteristics of different oils are different, and the pretreatment process and equipment will also be different. Zhongxing’s engineers can formulate a suitable and economical pretreatment equipment program according to the characteristics of the oil and your needs. You are welcome to consult.