Shanghai's food safety authority is consulting experts about regulations to standardize the operation of vending machines for ready-to-eat food.
The machines have become common in the city, thanks in part to the advent of mobile payment systems and advances in artificial intelligence technology.
The regulations, which are being drafted by the Shanghai Food and Drug Administration, cover vending machines that dispense fresh food and beverages, such as orange juice, coffee, coconut juice, noodles and even hairy crabs.
Popular among white-collar workers because of their convenience, the machines are not covered under current regulations.
After carrying out risk assessments on multiple vending machines last week, experts said standardization of their design and operation - including microbial contamination control, sterilization and cleaning - is imperative.
Last month three vending machines in the city made news headlines for their "magical" production of hot noodles in less than a minute.
Bowls of frozen noodles are defrosted quickly using steam, which is piped in, and then boiling water and sauces are injected into the bowl through another pipe.
While use of the three machines was suspended indefinitely, awaiting official approval from the Shanghai market management department, experts said the machines themselves can also pose hygiene risks if not managed properly.
"The second pipe is extremely vulnerable to microbial contamination," said Li Shuguang, a professor at the School of Public Health at Fudan University in Shanghai.
"The temperature of the pipe is over 100 C when water is flowing through it, but in between orders it will decrease to 25 to 30 C, which invites bacterial reproduction," Li said. "Operators should submit reports regularly to prove that their machines are clean enough to prevent this kind of pollution."
Zhao Zhihui, director of the research management department at Shanghai Academy of Agricultural Sciences, said operators should also prepare emergency plans to tackle incidents such as power failures.
While local and national standards and guidelines are still in the making, Zhao suggested that vending machine makers should come up with a set of standards for operators to follow.