Gutter oil

Gutter oil, trench oil, sewer oil and tainted oil (Chinese: 地沟油 / 地溝油; pinyin: dìgōu yóu, or 餿水油; sōushuǐ yóu) are Chinese slang terms primarily used in China and Taiwan to refer to recycled oil.

It can be used to describe the illicit practice of restaurants reusing cooking oil that has already been cooked with longer than safety codes permit. It can also be used to describe the reprocessing of rancid yellow grease collected from sources such as restaurant fryers, kitchen and slaughterhouse waste and sewer drains.

The usage of gutter oil is highly frowned upon and often leads to prosecution. For example, selling gutter oil in China can result in lengthy prison sentences or the death sentence with reprieve. For example, in 2014, businessman Zhu Chuanfeng was sentenced to the latter for selling gutter oil. That same year, a major gutter oil scandal was uncovered in Taiwan. In 2015, Yeh Wen-hsiang, who was the chairman of a Taiwanese food company, was sentenced to 22 years imprisonment and fined the equivalent of $1.6 million for selling 243 tonnes of gutter oil.