Gutter oil

Gutter oil (Chinese: 地沟油; pinyin: dìgōu yóu, or 餿水油; sōushuǐ yóu) is a term used in mainland China, Hong Kong, Macao and Taiwan to describe illicit cooking oil which has been recycled from waste oil collected from sources such as restaurant fryers, sewer drains, grease traps and slaughterhouse waste. The issue is frequently found in the People's Republic of China. Reprocessing is often very rudimentary; techniques include filtration, boiling, refining and the removal of adulterants. It is then packaged and resold as a cheaper alternative to normal cooking oil. Another version of gutter oil uses discarded animal parts, animal fat and skins, internal organs, and expired or otherwise low-quality meat which is then cooked in large vats in order to extract the oil. Used kitchen oil can be purchased for between $859 and $937 per ton while the cleaned and refined product can sell for $1,560 per ton. Thus there is great economic incentive to produce and sell gutter oil. It is estimated that up to one in every ten lower-market restaurant meals consumed in China is prepared with gutter oil. This high prevalence is due to what Feng Ping of the China Meat Research Center has made clear: "The illegal oil shows no difference in appearance and indicators after refining and purification because the law breakers are skillful at coping with the established standards."

The first documented case of gutter oil in mainland China was reported in 2000, when a street vendor was found to be selling oil obtained from restaurant garbage disposals.

The first documented case of gutter oil in Taiwan was reported in 1985. In a subsequent investigation, 22 people were arrested for involvement in a recycling oil ring over 10 years based in Taipei. The worst offender was sentenced to 7 years in prison.

Additionally, some reported an earlier incident in Taiwan in the 1960s, where "trench oil" was imported from Japan to Taiwan and then used in food processing.

...
Wikipedia