Fragrant Peanut Oil Production Line

The peanut oil production line is the extraction process of fragrant oil from peanut kernel by adopting the unique pressing technology. Peanuts are high-oil-containing oilseeds. Currently, the unique pressing processes are suited to extract high-flavored edible oils, which has really achieved “no chemical production”. The fragrant peanut oil obtained by pressing process maintains the natural ingredients and aroma of peanut oil, and it is rich in antioxidant vitamin E and has a long shelf life, so there is no need to add chemical antioxidants for storage; it is a pure natural oil products that are produced by combination of modern and traditional technology. With the improvement of living standards, the fragrant peanut oil is deeply loved by consumers for its unique pure fragrant flavor and have a broad market prospect. And the production line can be customer-made according to material variety, factory location, and labor resource.

pressed peanut oil manufactured by peanut oil pressing production line

Peanut Oil Production Process and Operating Points

In order to ensure the nutrition, flavor, and safety of fragrant peanut oil and reduce the cost, we adopt a physical squeezed method in the peanut oil production line. And the features of the pressing line are: (1) Extraction adopts pure physical pressing method to completely avoids the contact of raw materials and chemical solvents throughout the entire production process; (2) To abolish the unfavorable refining process which affects the quality of finished oil, such as solvent leaching, alkali refining and deodorization, so as to ensure the natural nutrients in the refined oil. (3) The refined oil is stored in an underground storage and the cooling water coil technology is used to ensure long-term storage.

1. Production Processes

1.1 Raw Material

The raw material which is used to produce fragrant peanut oil is fresh, full-grained, undamaged, mildew-free, free of insects and has not undergone an aging period. Raw materials would be cleaned by removing immature, damaged, and moldy grains during the cleaning process.

1.2 Process Flow of Peanut Oil Production Line

peanut oil press processing flow

1.3 Process Parameters and Procedures

Peanuts are cleaned and shelled, medium-sized peanuts are screened (about 25% of the treated amount), and the rest are large- and small-sized peanuts (about 75% of the treated amount). The large-sized and small-sized peanuts are broken, rolled and steamed. The medium-sized peanuts are crushed and cleaned by red skin eliminator, then being baked. Finally, the three sized materials are mixed and then pressed in the press to obtain the crude oil. After pressing, the oil is settled and filtered to produce a fragrant peanut oil.

1.4 Operating Points

Stones, metals, etc. may damage mechanical equipment; moldy, insect-infested peanuts will seriously affect the quality of the oil. In order to reduce oil loss, improve oil yield, ensure high quality of oil, and prolong the service life of equipment, the cleaning process should be strictly controlled. Metals could be removed by magnetic separation, using magnets to remove magnetic impurities in raw materials. Other impurities like stones are removed by self-regulation vibrating sieve, using peanuts and impurities’ difference in the particle size and weight, with the help of peanuts and impurities in the relative movement of the screen surface.

  • Equipment: Self-regulation vibrating sieve, magnetic separator
Vibrating cleaning screen for screening impurities from soybean Magnetic separator for cleaning soybean

Self-regulation vibrating sieve is widely used for separating impurities of large, medium and little-sized in grain, the machine has many features like the simple structure, smooth operation, low noises and consumption, good cleaning results, etc.

The magnetic separator has the horizontal and vertical type. The separator is made of stainless steel, and the raw peanut flows through the body and the magnet separator extracts contaminants.

In order to increase the oil yield, improve the quality of the oil and cake, reduce the equipment wear, increase the effective production capacity of the equipment, and facilitate the follow-up processes such as embryo rolling, the peanuts are shelled after cleaning.

  • Equipment: Peanut shelling machine
Peanut dehuller large scale peanut shelling machine

The shelling machine consists of racks, fans, rotors, single-phase motors, screens (number two), feed hoppers, vibrating screens, V-belts and its transmission belts.

  • Working principle

The peanuts are fed continuously and fall into the coarse grating firstly. Due to the force between the rotation of the stainless steel plate and the fixed grating, the peanut shells are separated from the kernels, then peanut kernels and shells pass through the grid at the same time. After they pass through the air duct, most of the peanut shells are blown out of the machine by wind, and unshelled kernels and some unpeeled peanuts fall into the gravity sorting screen together. After re-screening, the peanut kernels are separated by the screen and passed through the outlet, and flowed into the sacks. The unpeeled would flow into the hoist, and then into the fine-grained grid to perform secondary shelling. Then through screening, you can achieve full stripping.

The large and small peanuts are then separated by vibrating screen and as a raw embryo material in the main processing line, the middle size peanut for frying materials in the deputy processing line, the two processing line are treated separately. The ratio of raw embryo material to hot air baked material is 3:1.

  • Equipment: Peanut kernel grading machine

peanut grading machine

This machine uses five-layer folding structure and the automatic feeding device, four to five different sizes of peanut kernels can be screened at a time, and by changing the screen pieces, can achieve the required screening purpose. Peanut kernel grader has characteristics of the compact and reasonable structure, high efficiency, low cost, convenient and reliable use, which is applicable to select peanut, via a selection can achieve precise classification standard.

The purpose of crushing is to remove peanut’s skins, after crushing, the red skins can be sucked out by a wind separator, and the separated peanut red skin can be used as the raw material in medicine and chemical industry. Through crushing, the large-sized peanuts have a smaller size. Peanuts could be broken into 4 to 6 pieces, and moisture of crushing is controlled in 7% to 12%.

  • Equipment: Peanut crushing machine

peanut crushing machine

Double-pair tooth roller crushing is the key process of oil preparation for large grain (soybean, peanut) oil crops in oil processing enterprises. The crushing effect directly affects the quality and output of the rolling process. The crusher can meet the crushing demand of different output of 20T~1500T per day.

  • Features of peanut crushing machine
  1. The whole machine adopts full sealing safety protection.
  2. The crushing roller is cast by centrifugal composite technique, using high alloy wear-resistant material.
  3. Reasonable tooth pitch was designed so that the crushing effect and output reached perfect combination.
  4. The bearing adopts SKF imported original product, automatic cooling of bearing belt fan, lubrication technology in bearing collection, which can be maintained under working condition.

After crushing, peanuts are rolled through the instantaneous extrusion force between the two rollers to form the embryo slice, the shape of the peanut is changed, the oil path is shortened, which is beneficial to the oil extraction. Please note: The embryo slice which can be sieved through 1mm sieve hole is not more than 10~15%, and the embryo thickness is below 0.15mm.

Equipment: Peanut rolling machine

peanut tooth roller

Peanut rolling machine is used for the processing of oil embryo pieces. The embryo rolling machine consists of a feeding device, a roller device, a hydraulic device, an adjusting mechanism and a transmission device. The start-up, operation, feeding, rollers tightening. and rollers loosening of the rolling mill are all controlled by the electrical control system program. The machine has reliable quality, simple operation, compact structure, beautiful appearance, low noise, stable operation and high output.

Steaming and baking process are divided into two processing lines.

Equipment: Peanut baking machine, ZCL steaming cooker

rotary oilseeds roasting machine and vertical cooking machine

I. Hot air baking

The total amount of 25% to 30% of the peanut kernels is sent to a hot air baking oven where the peanut is heated to 18~200℃. The roasting temperature is the key factor for the fragrant peanut oil. The temperature is too low and the fragrance is lighter; the temperature is too high and the oil is easily gelatinized.

Please note: In order to prevent the gelatinization and spontaneous combustion of the oil, it should be quickly cooled after being baked, and then rolled into granules after cooling with a tooth roller crusher.

II. Steaming

Using a five-layer vertical steamer to steam the raw embryo. The 1st to 2nd layer of steamer should be fully loaded to play a role of steaming; the 3rd to 5th layer should be loaded shallow, which has an effect of removing moisture; the discharge temperature should be 108℃ to 112℃, and the moisture content should be 5% to 7%. To ensure that peanut oil has a strong aroma, the steam pressure of steam boilers should not be less than 0.6mpa.

1. Equipment: ZCL steaming cooker

ZCL steaming cooker is a equipment that processes the raw, rolled embryo into the mature embryo by wetting and steaming and frying, so as to meet the technological requirements for subsequent oil extraction. After softening the oil, the quality of the rolled product can be improved, thereby improving the oil yield and improving the quality of the oil. ZCL steaming frying pan is composed of pan body, steam inlet pipe, condensate water pipe, stirring device, speed reducer, automatic material controlling door and material outlet.

2. Process characteristics of ZCL steaming cooker

  • It has the feature of condensing grease and increasing oil yield.
  • The machine could adjust the oil structure to prevent blocking the oil path.
  • The wetting and softening of peanut can improve the quality of rolled embryo, and then improve the oil yield, and improve the quality of crude oil, which is the necessary equipment for the pretreatment of peanut oil in peanut oil factory.

The steamed peanut is then pressed by expeller for oil extraction. Using a mechanical screw press, the original cell structure of the peanut is destroyed under mechanical force to obtain a pressed crude oil.

Equipment: ZY32 type screw oil press

zy32 peanut oil screw press

ZY32 spiral oil press is a large-scale continuous oil extraction equipment. It has passed ISO9001-2000 quality system certification and is suitable for pressing high oil-containing seeds such as cottonseed, rapeseed, ramie, sunflower seeds, and peanuts. With the features of large processing capacity, low power consumption, low operating cost, loose cake structure without breaking, easy solvent penetration, low residual oil rate, etc., ZY32 type screw oil press is an ideal oil extraction equipment for large-scale oil plants.

1. Performance characteristics of screw oil expeller

  • ZY32 spiral oil press is suitable for pre-pressing or one-time pressing of oilseeds with high oil content in large plant oil plants. It is also suitable for crushing animal carcasses in pollution-free projects. With its reasonable structure design, it not only ensures high output but also is easy to operate and maintain.
  • The screw oil expeller is a kind of continuous oil press equipment, which uses screw shaft to rotate the embryo in the press cage and the embryo is extruded into the cake while the oil is squeezed out. Compared with “hydraulic press”, the mechanical screw press has the following characteristics: continuous production, the large processing capacity of the single unit, adaptability to various oil materials, dynamic pressing and extrusion, short pressing time, high oil yield, the easy crushing of thin cake and low operating strength. The disadvantages are high maintenance requirements of mechanical failure and greater thermal impact of cake.

2. Main structures of screw oil press

ZY32 type pre-pressing machine is mainly composed of steamer, feeding mechanism, press cage, press screw shaft and transmission device.

  • Steamer: It is a vertical two-layer steamer and is mounted on a bracket. It can adjust the moisture of the material embryo before pressing and heat the embryo.
  • Feeding mechanism: it is composed of a feeding shaft with a spiral leaf at the lower end, a feeding head, and a feeding hopper, and a sluice board is installed between the inlet of the feeding head and the discharging port of the steamer to control the flow of the falling material. A feed hopper is placed below the feed head from which the feeding conditions can be observed and the pressed embryo could be extracted as a sample. The feeding shaft is driven by a steamer reducer.
  • Press cage and the press screw shaft: Press cage and the screw shaft are the main working parts of this equipment. The embryo pressed from the feeding mechanism continuously enters the gap between the press cage and the press screw shaft (called pressing chamber). Due to the rotation of the screw press shaft and the narrowing space of the pressing chamber, the embryo is subjected to strong pressure. The oil is squeezed out and flows out through the gap of the cage bar.

Please note: A cake adjusting mechanism is used to adjust the thickness of the cake at the outlet of the squeezed screw shaft. The end of the squeezed screw shaft is connected to the output shaft of the gearbox of the equipment.

After a long period of precipitation, the crude oil can be filtered by a vertical leaf filter and sent to a refining plant. The pressed cake can be crushed and sent to a leaching plant for secondary leaching. Leached oil is refined and sold as ordinary oil.

1. Crude oil refining process flow

Filtration of oil→primary cooling→adding filter aids→secondary cooling→48h precipitation→filtration→refined oil→filter cake

2. Process description

  • Primary cooling: The temperature of the crude oil sent from the press workshop is generally 60℃ to 70℃. To save energy, the oil is first cooled with tap water (cooling water) under low-speed stirring (30rpm) and the temperature is reduced to near room temperature.
  • Adding filter aids: The purpose of adding filter aid is to improve the final filtration effect, accelerate the formation of filter cake, reduce the content of phospholipids and peptized impurities in refined oil; filter aids are activated carbon and solid peanut cake powder; the added amount is about 0.1% of the weight of the oil.
  • Secondary cooling: The peanut oil is cooled to 10℃ to 15℃ by low-speed stirring with frozen brine, and then kept to stand for 48h in heat preservation.
  • Filtration: After 48 hours’ precipitation, oil is pumped into the frame filter press for filtration. In the process of filtration, the suspended impurities can be separated from the crude oil and the colloidal impurities in the oil, such as mucus and protein, can be further removed, too.

Please note: The filtered oil which is obtained before the formation of the filter cake is relatively turbid and should be filtered again after the filter cake is formed. After filtration, the obtained oil can be packaged.

  • Filter cake treatment: The filter cake from the press workshop can be pressed again; the filter cake obtained from the refining workshop can be added to the meal for feed production.

Equipment: Frame filter press

1.5 Peanut Oil Storage

The appropriate condition for peanut oil storage is 8% moisture content and the temperature which does not exceed 20℃. Sealed storage can prevent the infection of pests and the influence of the outside temperature and humidity, which is conducive to maintaining a low temperature.

Peanut oil is stored at a temperature below 15℃ in a sealed container to prevent lipase hydrolysis and oxidation, and to avoid the increase in acid number and peroxide value. The average temperature of the ground below 4m is below 20℃, so the storage house is built underground.

Factors That Affects the Fragrance of Peanut Oil

groundnut oil

The Effect of Peanut Raw Material Itself

The oilseed used to produce fragrant peanut oil requires full grain without aging period. Immature, broken, mildew and aged grains cannot be used to produce aromatic peanut oil: The acid value of oil produced by immature and aged grains is higher and the flavor is poor, while moldy and damaged grains are liable to be contaminated by aflatoxin. Therefore, in the production process, these oilseeds must be separated for the ordinary secondary oil processing alone.

The Effect of Baking Temperature

Hot-air roasting is a key process for the production of fragrant peanut oil. The flavor of peanut oil has a direct relationship with the baking temperature. The temperature is too low and the fragrance is lighter; the temperature is too high and the oil is prone to scorching. The baking temperature is generally controlled at 180℃~ 200℃. In order to prevent the gelatinization and spontaneous combustion of the oil, it should be cooled immediately after baking.

The Influence of Steaming

The steaming of embryo is another important step in the production of strong fragrant peanut oil. The level of oil content, flavor and color, and the content of phospholipids and pectin-soluble components in fragrant peanut oil are directly related to the steaming process. High-moisture steaming embryo technology should be adopted to adjust the moisture content of the oil in the steaming cooker to 12% to 13%; within the pressure range that the equipment can withstand, try to increase the pressure of indirect water vapor, generally controlled at 0.6MPa~MPa; and enterprises with conditions shall be encouraged to use hot water steam. In the process of steam cooking, it is necessary to make the phospholipids and peptic substances absorb water to combine with the protein, which is the key to guarantee the qualified test of the refined oil 280℃ heating and improve the transparency of refined oil.