The pre-treatment before edible hydraulic pressing mainly includes the following steps: cleaning and removing stones, peeling the shell, crushing, rolling the embryo, and steaming and frying. These steps play a crucial role in the production process of edible oil, taking peanut oil as an example:

Cleaning and removing stones: Peanut raw materials may introduce impurities such as sand, stones, and soil during harvesting, drying, and transportation, which can affect the normal operation of equipment and the quality of oil products. Therefore, it is necessary to clean and remove stones from the raw materials, remove impurities such as stones and soil from the peanuts, reduce the wear and tear of the equipment caused by impurities, and extend the service life of the equipment

Shell stripping: The purpose of shell stripping is to remove the outer shell of peanuts, reduce the wear of peanut shells on oil extraction equipment, and lower their adsorption of oil, thereby improving oil yield

Crushing: Crushing large peanuts into uniformly sized small particles to increase surface area, which is beneficial for the transfer of temperature and moisture in the subsequent steaming and frying stages, and improves oil yield

Rolling embryo: By using a rolling embryo machine to press peanuts into thick, thin, and uniform cakes, the peanut cell tissue is destroyed, the surface area is increased, which is beneficial for the coagulation of oil during steaming and frying, shortening the oil extraction distance, and improving the oil extraction speed

Steaming and frying: Fully stir fry the crushed peanuts at 130-150 ℃, control the moisture content and temperature, thoroughly destroy the oil cells, denature the proteins, coagulate the oil, increase the oil extraction rate and improve the quality of the oil

These preprocessing steps not only improve the oil yield, but also enhance the quality of the oil. Through these processes, the raw materials are pressed in an oil press to obtain pressed peanut oil, which is then refined to remove impurities and ultimately produces the edible oil we use in our daily lives