On Oct 5, nine people in Jidong county, Heilongjiang province, fell ill after dining together at home. On Monday, the last of the nine people died in hospital.

The deaths were caused by bongkrek acid, a fatal acid produced by a bacteria that contaminates suantangzi, a kind of corn noodles they had eaten that day. The bacteria usually contaminates fermented rice-or flour-based food and can survive even when the food is boiled at high temperatures. The fatality rate from such infection is higher than 50 percent.

On Monday, the National Health Commission warned people against eating fermented food left over for a long time. It said 14 bongkrek acid cases involving 84 people had been reported since 2010, in which 37 people had lost their lives.

On social networking sites, some users said people had been eating the traditional food for generations and wondered why no such deaths had been reported in the past. However, they should realize that there was little health awareness in the past, and food poisoning deaths went unnoticed or failed to catch the attention of the authorities. But today, food poisoning deaths are unlikely to escape attention.

The NHC named some other popular snacks, including fermented glutinous rice dumplings and fried rice noodles, which, like suantangzi, are hand-made, fermented, and usually made at home or by hawkers.

It advised people to cook small amounts at a time to prevent leftovers. That would also be in accordance with the leadership's call to prevent food wastage.

Also, it is important for local market regulators to strengthen the supervision of foods sold by vendors by conducting random testings to ensure they are safe for consumption.

There is no bar on people enjoying fermented food, but safety must always come first.