Peanut Oil Production Line

 

The Process of Peanut Pretreatment

The peanut pretreatment processes include cleaning and separating of hull & kernels. According to pressing temperature, there are two groundnut oil pressing technologies: hot pressing and cold pressing.

Peanut Cleaning

There are impurities in peanuts before processing. First, a vibrating screen is needed here to remove the impurities from the groundnut. After screening, the impurity content is no more than 0.5%, and the groundnut kernel content in removed materials is no more than 1%. Then the stone is separated from the peanut by a destoning machine.

Peanut Shelling and Separating of Hull & Kernels

When the peanut sheller works, the groundnut are delivered into the hopper quantitatively, uniformly, and continuously. Under repeated strikes, friction, and collision of the rotor, the peanut hulls are broken. Then the groundnut kernels and broken hulls pass through the sieve in a certain hole diameter (the sieve of big hole diameter for the first shelling, and a small hole diameter for the second cleaning). Under the blowing force of the rotating fan, the peanut husks in lightweight are blown outside, and the groundnut kernels pass through the sieve to achieve the cleaning effect.

Peanut Crushing & Softening, Flaking, Cooking

The purpose of this process is to crush the peanut into a certain granularity, which can meet the condition of flaking. After crushing, the surface area of the groundnut is increased, better for the transfer of temperature and moisture when softening.

The peanut kernel is soft, normally it does not need to be softened. Sometimes it can be flaked directly only after the suitable heat treatment. Generally, cooking is adjusted according to the conditions required for hot pressing. When the moisture content is close to 1-2% and the temperature reaches 120-130℃, it is time to finish cooking and begin to press.

Peanut Oil Pressing Process

The peanut pressing processes can be divided into three stages, which are the feeding stage, the main pressing stage, and the cake forming stage. The most common groundnut oil pressing machine is the screw oil press.

Hot pressing is the traditional method of pressing peanut oil. With a high rate of oil output, good taste, and convenient storage, it is popular for home use. However, because of the high production temperature, the peanut protein is usually severely denatured and loses plenty of nutrients.

Cold pressing technology is often applied in large peanut oil production plants. The production temperature is conducted under 60℃, which is beneficial to preserve the nutrients and comprehensively utilize peanut protein in groundnut oil. The disadvantage is low oil yield, not suitable for small oil plants.

The pressed groundnut meal cakes can be used as animal feed, or the residual oil can be further extracted through the extraction process.

Peanut Oil Refining Process

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

Refining is to remove impurities, odors, and pigments from groundnut oil and improve the quality and taste of the oil. The refining process mainly includes steps such as degumming, deacidification, decolorization, and deodorization.