Can walnuts, soybeans, rice, and pumpkin seeds be pressed for oil? How much oil can you get from one jin?
Walnuts, soybeans, rice, and pumpkin seeds are all things we commonly eat, so can they all be pressed for oil? How much oil can you get from one jin? It is understood that pumpkin seeds and rice cannot be pressed for oil, while walnuts and soybeans can. Below is a detailed introduction.
Walnuts and soybeans can be pressed for oil, how much oil can you get from one jin?
Walnuts:
Walnut is an oilseed crop with a very high oil content; the oil yield of walnut kernels can reach 40%-50%, and walnut oil has the effects of strengthening the body, nourishing the brain, preventing cardiovascular and cerebrovascular diseases, improving endocrine system function, and supplementing calcium.
The oil pressing method is basically the same; the main thing is to see whether the walnut oil content is high and whether it meets the requirements for oil pressing. However, wild walnuts seem to have low oil content and cannot yield much oil. Nowadays, high-quality walnuts are generally used for oil pressing, first because the kernel yield is high, and also because the oil yield is high, which is what gives it economic value.
Generally, 4 jin of walnuts can produce one jin of oil, because the oil yield of walnut kernels is about 70%, 500*0.7=350 grams, and one jin of walnut kernels yields only 7 liang of oil.
Walnuts of different qualities have different oil yields. The walnuts used for oil pressing on the market have an oil yield of about 30%, which is basically the highest oil yield.
Soybeans:
Soybean oil processed from soybeans is one of the important edible oils. It is a semi-drying oil and a good vegetable oil.
1. Moisture adjustment and cleaning to remove impurities. Soybeans and yellow soybeans from different regions have different moisture levels and different types, so the moisture of these raw grains needs to be adjusted. This step is not optional. The moisture requirement for soybean oil extracted by a soybean oil press is no higher than 12%, and the impurity content is below 0.5%. The moisture and impurity content will directly affect the quality of the oil. Although the soybean oil press can be equipped with a refining process, the degree of refining is limited. Moreover, if the impurity content is too high, it will also cause oil passage blockage and accelerate the wear of oil equipment parts.
2. Peeling and shelling of soybeans and yellow soybeans. If soybeans are not shelled during oil extraction, it will affect the oil yield of the oil press and the production efficiency of the oil machinery. In addition, there will be some impurities and pesticide residues on the soybean skins. Once they enter the oil, they will affect the color and quality of the oil.
3. Soybean crushing and flaking. This step can be set up or not. The main function of this step is to press the soybeans into flakes, increase the oil extraction area, and improve the processing capacity of the oil equipment. Of course, flaked soybean blanks will also reduce wear on the oil press screw.
4. Seed roasting. This step is a signature process in hot pressing, but it is not needed for cold pressing. Generally speaking, the oil yield and production efficiency of hot pressing are higher than those of cold pressing.
Depending on the soybean variety, the oil yield is mostly between 18--22%. Generally speaking, the genetically modified soybeans currently from the United States and Brazil are mostly high-fat beans, so the oil yield is higher.
Rice and pumpkin seeds cannot be pressed for oil
Rice itself cannot be pressed for oil, but the layer of rice bran between the rice and the rice husk contains the rice skin and rice germ, which include many nutrients from a rice grain. In fact, many nutrients in the rice we usually eat have been lost, and rice bran oil is extracted from this nutrient-rich rice bran, so this oil is very nutritious.
Pumpkin seeds have a low oil content. So currently no one uses them to press oil.