While consumers worry about the consequences of eating food cooked in recycled oil, officials have confirmed that the oil used by the US fast-food giant KFC is safe.
Last week, Chinese media reported that the cooking oil at KFC restaurants is often used for four days in a row or longer, raising concerns about the safety of their food.
On Tuesday, the Shanghai Municipal Food and Drug Inspection Institute inspected the oil found at a KFC restaurant in Shanghai and deemed it to be safe.
"Our test result showed that all the main indicators - the acid value, oxidation and polarity composition content of KFC's cooking oil - meet national standards," Qiu Congqian, deputy director of the institute, said on Wednesday.
Qiu said they tested the safety of oil based on whether it is within the standards, rather than how many days it has been in a restaurant.
Earlier this week, KFC issued a statement on its website denying the information reported by the media. The company said the oil in its restaurants is tested every day before it is used and that the oil meets the country's safety standards.
KFC has strict requirements for the use of cooking oil, the company said.
Every day its restaurants run the oil they have used through filters to remove food residue. With special test strips, they monitor the oil's chemical composition. If they discover oil that is on the verge of becoming substandard, they throw it away.
"We conduct tests on the oil every morning and every night, and record how long the cooking oil is used," said an employee at a Shanghai KFC, who declined to be named.
Despite the official safety tests and KFC's statement, consumers are worried that recycled cooking oil is dangerous.
A woman surnamed Zhang, who is in her 40s, said, "After hearing the news, I felt extremely upset. I don't think I will go to KFC anymore.
"We have all known that some chemicals will form if oil is frequently re-used. This may have some effect on people's health. It's terrible to know that KFC doesn't replace its cooking oil for days," she said.
"It may cost too much for businesses to discard their cooking oil every day. But those in the food business or industry should demand a lot of themselves. I think food businesses should let the public see how they make food. That may entail some difficulties in practice but will really help to inspire consumer confidence," said a man surnamed Xu, who is a middle school teacher.
Experts said using oil at high temperatures causes the concentration of acrylamide and trans- fatty acids in deep-fried foods to increase greatly, which may endanger consumers' health.