Food safety has become a top concern in China as a string of safety scandals, particularly the one in 2008 when melamine-tainted baby formula caused the deaths of at least six infants and sickened 300,000 others, have crippled customer confidence.

Shanghai municipal legislator Xu Liping agreed that the weakness of food safety supervision was at the grassroots.

"The number of inspectors cannot be increased infinitely. The key is to improve their competency and work style," said Xu.

Zhao Renrong, deputy to the Shanghai People's Congress, the city's legislature, proposed that a nationwide blacklisting system be established based on the credit records of food business managers.

"Without such a system, a business owner who breaks the law can easily run away from his problems by reopening another shop under the name of his relative," said Zhao, also chief of the Tingdong Village Branch of the Communist Party of China in Shanghai's Jinshan District.

Although many places including Shanghai have started to experiment with blacklisting lawbreakers, Liu Zhengguo, director of the enterprise credit management committee of the metropolis, said that a nationwide credit system was badly needed to prevent lawbreakers continuing their malpractice elsewhere in the country.

"We must ensure no Chinese can afford to have a bad record in terms of food safety in this country," he said.

Liu Boying, director of the Commission of Commerce in Hongkou district in Shanghai, suggested that digital technologies should be widely used to strengthen certification of products' origins.

For instance, consumers should be able to learn the exact breeding information of aquatic products by scanning the label, said Liu, adding that the biggest challenge was how to raise the enthusiasm of enterprises with certifications of origin.

To solve the problem, Shanghai has started legislation on compulsory certification of the origin of foodstuff, which may cover pork, vegetables, aquatic products, grain crops, dairy and cooking oil, according to the municipality's food safety supervision chief Yan Zuqiang.