Shortened oil is hydrogenated oil, which contains a lot of trans fatty acids, causing damage to developing children and human brain nerve cells. The repeatedly fried oil contains all kinds of harmful polymers, so it is poison on top of poison. \x1d\ However, the present situation is that the catering or food processing industry cannot do without hydrogenated oil, and it is impossible and unrealistic to use the oil only once, so we provide several methods for the landlord to filter the oil: \x1d\1) White gauze filtration. \x1d\2) Slice the white radish, poke the hole, fry it in oil, absorb dirt, and make the oil clear (the radish can be reused after being taken out and washed). \x1d\3) Egg shells are put in oil and let stand without heating, and absorbed by calcium carbonate.