Finding better ways to identify 'gutter oil'
Updated: 2011-09-20 07:47
By Zhou Wenting (China Daily)
Experts say nation's current tests fail to detect all illegally produced samples
BEIJING - The country's food safety and health watchdogs are working jointly on finding an accurate scientific method to identify "gutter oil", as the current national standard for the content of edible oil fails to disqualify the illegal sort.
Gutter oil, or illegally recycled cooking oil, is often scooped up from sewage drains and gutters behind cooking establishments and then sold to small restaurants. More broadly, it also refers to oil refined from low-quality pork and animal offal as well as oil overused for fried food.
Seven central departments, including the Ministry of Health and the State Food and Drug Administration, have jointly initiated a project to develop better testing methods for gutter oil, and an expert panel formed by the authorities on edible oil processing, food safety, health inspection and chemical analysis has been established to examine and verify the proposed detection methods.
Many experts have claimed that the country's current standard, which has nine test indicators, including acid value and pesticide residue, could easily allow illegal oil to slip through. Police in Ninghai county, Zhejiang province, recently sent 10 samples of gutter oil they had confiscated in raids for tests, but by current standards only two samples were found to be of poor quality.
Some experts said it is technically difficult to distinguish reprocessed oil from ordinary cooking oil.
"The illegal oil may appear to be the same in indicators after being refined and purified," said Feng Ping, chief engineer at China Meat Research Center.
"For example, law breakers know watchdogs will test acid value, so they cover bad smells in various ways."
It is harder to detect illegal oil after it is blended in ordinary cooking oil, according to Fan Zhihong, associate professor with China Agricultural University's college of food science and nutrition engineering.
"Some crafty manufacturers add 10 or 20 percent worth of bad oil to normal oil products after refining it and later dilute the mixed oil many times. It is difficult to find fault with it in appearance, water content and acid value."
Food safety experts said gutter oil is unacceptable although no scientific experiment has been carried out to reveal how carcinogenic it is.
But they said the problem should be tackled by close monitoring of the production process instead of by detection after it has been made.
"What the police did this time is great, because all of the health, quality and market watchdogs bet on detection technology, but police caught the illegal oil makers during the production process," said Chen Junshi, a food safety expert at the Chinese Academy of Engineering.
Chen was referring to the fact that police detained 32 suspects who allegedly produced gutter oil and sold it to restaurants during the latest nationwide crackdown on illegal oil. More than 100 tons of the oil were seized after the exposure of a criminal network spanning 14 provinces, the Ministry of Public Security said on Sept 13.
"It is wiser to stop the illegal behavior when it is happening than to depend on testing end products," Chen said.
"The central authorities might not know about illegal production, but local governments cannot claim they don't know what is going on."
The Beijing Food Safety Monitoring Center has found four effective indicators that can tell gutter oil from standard cooking oil: polycyclic aromatic hydrocarbon, cholesterol, conductivity and specific genes.