The difference between screw oil press and hydraulic oil press

Hydraulic press and screw press are both physical presses, but hydraulic press and screw press are essentially different:

The hydraulic oil press adopts a static pressing method, which is called soil pressing in the south and stupid pressing in the north. It is the continuation of the essence of my country’s thousand-year-old wood pressing. It is a typical cold pressing process. The protein and nutrient content of vegetable oil is maximized. The original color and flavor of the extracted oil can be eaten directly without filtering. General high-end oils, such as tea oil, olive oil, and linseed oil, are generally required to use hydraulic pressing due to their high nutritional value and high price; now many peanuts, soybeans, and rapeseeds are also hydraulically pressed, and the squeezed oil tastes better. good.

Changde, Hunan is the original place of origin of the earliest horizontal hydraulic oil press, which is represented by "Tangqiao", "Dingliang" and "Hegde".

The screw press oil extraction is a dynamic pressing method. The pressing process is accompanied by friction, and the high temperature inside the press chamber, often exceeding 200 degrees, is a typical hot pressing process. The temperature is too high, resulting in severe damage to the protein structure, producing phosphoric acid and other acid value substances, the color is black, the squeezed oil needs to be filtered, and sometimes saltwater is needed to remove the acid. Nowadays, most rapeseed oil is screw pressed, so people often think that the oil is not as delicious as when they were young (more than ten years ago, horizontal hydraulic pressing of rapeseed was more common (for cakes)). The characteristics of screw press are large output and simple process.

In addition, the hydraulically squeezed cakes are round cakes. Because there is no overheating in the static pressing process, the dry cakes are fully preserved in protein and have high nutritional value. They can be used as a feed or high-grade fish bait for pigs and fishing; while spiral squeezing The oil cake is a flaky dry cake. Due to the high temperature during the pressing process, the nutritional value of protein and other nutrients is lost, and it can only be used as fertilizer or as a raw material for leaching.