A customer at a McDonald's in Beijing's Chaoyang district on Sunday. [Geng Feifei / China Daily]

Problems with major brands raise public concern over safety, Zhang Yuchen reports in Beijing.

Cheng Qizheng, 19, is a loyal fan of KFC, McDonald's and other foreign fast food. He grew up frequenting their shops, believing their products to be clean and trustworthy.

But doubts raised on Weibo dented the confidence of Cheng and many others.

The quality of the soybean milk at KFC was called into question. So were the burgers at McDonald's and the soup at Ajisen Ramen, a popular Japanese noodle shop.

Food safety was an issue in just one of these cases. The other two involved marketing claims and whether consumers thought the products were as good as advertised.

But people can be unforgiving because food safety is such an important issue.

"We do have food safety problems, but not as many as people think. And not every problem in the food industry is about the safety of the food," Chen Junshi, senior research professor at the National Institute of Nutrition and Food Safety, said.

KFC's problem started on July 28. A Sina micro-blogger writing under the name Fu Xiaoxiao Ki published a photo of boxes of soy milk powder piled outside a KFC outlet in Guangzhou, capital of South China's Guangdong province.

"Even street vendors' soybean milk is freshly ground. How can KFC sell it at such a high price when it is actually made from the powder? I feel cheated," the post read. It was reposted 30,000 times in one day and followed by extensive media coverage as well as the interest of food safety authorities.

KFC acknowledged on its website on July 29 that its soy milk is made from powder. But it also said the powder's Chinese producers follow KFC's special recipe, which makes sure the milk tastes similar to milk from freshly ground soybeans.

On Thursday, Beijing's health authorities announced that they had inspected KFC's 254 restaurants in the capital. They determined that the soy milk KFC sells is not made from freshly ground beans, but it is safe.