One of the cities that claims to be the birthplace of spicy hot pot, Chongqing, has introduced standards for the dish that, most notably, urge restaurants to stop reusing oil.

On Thursday, the Chongqing Commerce Commission issued a set of guidelines that cover everything from ingredients to cooking temperature. The guidelines suggest that restaurants advise customers from outside Chongqing on the optimal dipping time to achieve the best flavor. They also include definitions for certain terms, such as the dipping sauce used to cool down ingredients after they are lifted from the soup.

The move is intended to strengthen regulation of the hot pot industry in the southwestern city, and to “meet the needs of people’s increasing demand for a good life,” the Chongqing Daily reported.

In June 2016, the northwestern city of Xi’an issued regulations on producing roujiamo, a popular local snack known as a “Chinese hamburger.” Yangzhou, a city in eastern China’s Jiangsu province, in 2015 specified standards for the color, texture, smell, and ingredients of Yangzhou fried rice. In response, a commentary in Party newspaper People’s Daily argued that such regulations would inhibit culinary creativity.

One of the more contentious elements of the Chongqing guidelines pertains to the recycling of the hot pot broth. Many Chongqing-style hot pot restaurants prefer to reuse the buttery residue that remains after a meal as a base for the next day’s soup. Some consumers argue that these oils are more flavorful, but the guidelines call for an end to this practice on the grounds of hygiene.

In March, a Chongqing-style hot pot restaurant in the southern city of Guangzhou came under scrutiny after a local television station reported that the eatery changed its soup only once a week.

Yao Shun, a 29-year-old Chongqing native who lives in Shanghai, told Sixth Tone that people from Chongqing prefer it that way. “Most Chongqing people would agree that homemade hot pot never tastes as good on the first day as it does on the second day,” he said. “But it may not be easy for nonlocals to accept this.”

Yet Zou Sicong, another Chongqing native who co-owns a hot pot restaurant in Beijing, agrees that the practice of reusing oil is unhygienic. “It is too greasy; it feels good when you’re eating it, but it’s very uncomfortable afterward,” said the 26-year-old.

In November 2010, Chongqing issued regulations on food production that forbid the use of waste grease as an ingredient in new edible oil products. In November last year, the municipal government launched an initiative to turn Chongqing into a national model city for food safety.

“Hot pot originally was not high-end cuisine. It was created for laborers, for boatmen at the wharf,” restaurant owner Zou told Sixth Tone, explaining that Chongqing’s lower classes originally created the soup by cooking waste products from slaughterhouses, such as animal organs, with chilies and other spices.

The dish has since grown in popularity. Chongqing itself has 28,000 hot pot restaurants, according to the Chongqing Hot Pot Association, and many more are spread around China.

Four restaurant chains from Chongqing ranked among the top 10 national hot pot brands, according to the China Hospitality Association. Industry leader Haidilao, which serves hot pot in the style of neighboring Sichuan province, was hit with its own hygiene scandal in August when journalists discovered rats and other sanitation scares in kitchens at the chain’s Beijing branches.

Editor: Kevin Schoenmakers.

(Header image: Wei Yang/IC)