First the extraction of oil from a wood press can be traced back more than a thousand years. The old-fashioned wooden pressing equipment has been popular for more than 700 years. And it may have existed for more than a thousand years, because there is a record of using wooden oil pressing as a tribute to the court in the Tang Dynasty. It is precisely because of their appearance that a real professional oil extraction workshop has been produced.
Second,the traditional wood press oil extraction process is to put the packaged cake embryos into the press chamber of the wood press one by one. And arrange them in an orderly manner. After loading the embryo, insert a wooden block on one side of the seed cake. And then hit a wedge between the wooden blocks with a heavy hammer or a hanging ram. For this purpose, as the wedges are driven into the press chamber. The wooden blocks placed horizontally in the press chamber will exert a pressing force on the embryo to produce oil.
On the one hand, the manual swinging and hanging is also called the ram hitting the wooden wedge, which is the core link of the wood pressing process. Commonly known as “oiling”. In fact,hen the vegetable was squeezed, wisps of golden clear oil flowed out from the small opening in the middle of the oil tank. Add wooden wedges at the right time, squeeze the seed cake out of oil by physical action, until the oil is squeezed dry.
Precipitation and oil extraction
Finally,the squeezed oil flows into the oil tank through the stone trough under the oil lump, collects and precipitates. And after the oil is filtered and precipitated for 15-30 days. The impurities are separated from the oil, and it can be sold.
Disadvantages of traditional wood press oil extraction process
1. The oil yield is low, and the residual oil in the pressed cake can reach 7-10%, which is easy to waste.
2. The temperature of fried seeds cannot be precisely controlled. If the heating temperature is controlled too high, it is easy to produce benzopyrene.
3. There are many impurities in the oil, which has not been refined, has a low smoke point and is not conducive to long-term storage.
4. The production technology is backward, which will inevitably bring hidden dangers to food safety. For example, poor sanitary conditions and poor facilities and equipment.
In addition，the traditional wood press oil extraction process has high labor intensity, low oil yield and low productivity level. And the production environment is difficult to meet the food production standards of modern society.
Wooden pressing to make oil is a unique traditional folk craft of the Chinese nation, which contains the essence of five thousand years of civilization. Furthermore as a concentrated expression of the wisdom of the ancestors. Another,the wooden press craft has made great contributions to the inheritance and development of Chinese civilization and is indelible.