Waste cooking oil generally refers to all kinds of inferior oils existing in life, such as recycled cooking oil and repeatedly used fried oil. The biggest source of waste oil is the grease trap in the sewer of large hotels in the city. Long-term consumption may cause cancer, which is extremely harmful to the human body.

This three-no product, called "waste oil", is still composed of triglycerides, but there are many more toxic substances that cause disease and cancer than real edible oil.

The main component of "gutter oil" is triglyceride, and the chemical formula is C39H74O6.