In March of last year, reports on the widespread sale and use of recycled cooking oil shocked Chinese consumers. By one estimate, almost 1 of 10 meals in China is prepared with recycled oil, and China may consume 2 to 3 million tons of recycled cooking oil per year! Gross…
While periodic reports reach the papers of recycled oil operations found in Chengdu, Wuhan, Guangdong, Jiangxi, Hainan, and Fujian, Suluku looked at the situation in Beijing.
An investigation last summer by the Beijing Public Health Bureau inspected 279 roast duck restaurants but found no evidence of using or selling old oil. While it’s reassuring that some types restaurants are safe, we still have no data on other types of restaurants. Restaurant owners in Beijing have reported in the media that they will pay private companies to collect waste oil, and it’s anyone’s guess where that goes.
Unfortunately, with no standardized way of testing whether cooking oil is fresh or recycled, the government may be limited in how well it can regulate the problem. Last July the China State Council ordered a crackdown on recycled oil, and required restaurants to keep records of how they discard kitchen waste. The directive was an opinion issued on behalf of the national government but implementation falls to local governments. Preliminary commentary suggests the rules have been only weakly enforced and are generally ineffective.
When we asked Professor Luo Yunbo, 罗云波, who teaches at Beijing Agricultural University, he said he felt reused oil is a serous problem in Beijing. The oil from the supermarket is generally safe, he said, but small restaurants, especially those that cook Sichuanese and Hunanese dishes traditionally high in oil, may be cause for concern.
If you’re not sure the oil you bought is safe, Professor (罗云波) recommends the following tests:
Is the oil dark and cloudy looking, and not transparent?
Is there sediment in the oil?
Does the oil congeal at low temperatures?
If the answer is yes to any of these questions, you should be concerned. However, good-looking oil is still not a guarantee of fresh oil, and it’s very difficult to know if the oil in restaurant dishes is fresh or not.
The safest way is likely to avoid the types of restaurants mentioned above, and cook food at home so you can verify the oil source.
What is recycled oil and where does it come from?
Recycled oil is cooking oil that has been used, discarded, reprocessed, and sold again. Mid-sized Chinese restaurants (think 10-40 rmb dish, 50 tables, 家常菜 restaurants) can go through up to 2 barrels of oil per day. There is no government service that collects recycled oil, so restaurants may pay collectors to haul it away or will sell it to private companies. Illegal processors may then sell the oil back to restaurants.
Robert Earley, the Clean Transportation Program Manager at iCET (Innovation Center for Energy and Transportation), an NGO headquartered in Beijing that has studied the potential of waste oils for biodiesel production in China, confirmed this process.
“Generally we see that waste oil collection is one of the few lucrative businesses that is really controlled locally, and ends up being quite corrupt, with waste oil basically going to the highest bidder,” he said.
能源与交通创新中心（iCET, Innovation Center for Energy and Transportation ）是一家总部设在北京的非政府组织，它曾就在中国用废油生产生物柴油是否可行进行评估。Robert Earley ，iCET的清洁交通项目经理，证实了加工过程的可行性。
People have also been caught collecting oil from drainage gutters as a source for reprocessed oil. That’s where we got the term 地沟油 di4gou1you2 (gutter oil).
Why do people use it?
The allure of the second-hand oil is driven by economics: reprocessed oil can be less than half the price of fresh oil. The entire illegal oil industry is estimated at 1.5-2 billion RMB per year. Depending on its size, restaurants can make between 10,000 – 2 million RMB per year selling oil and kitchen waste to collectors.
Why is recycled oil dangerous?
When vegetable oil is heated repeatedly to high temperatures, it forms a number of toxic by-products. Polyunsaturated fats like soy, canola, sunflower, and corn have been shown to produce carcinogenic polycyclic aromatic hydrocarbons (PAH), and the toxin 4-hydroxy-trans-2-nonenal (HNE). Before and after cooking, peanut oil may be contaminated with aflatoxin, a powerful carcinogen. As a result, reused oil has been linked to atherosclerosis, inflammatory joint disease, birth defects, digestive track problems, and may be carcinogenic.
What CAN we do with all that oil?
Professor Luo said converting waste oil into biofuels or animal feed would be an appropriate way to dispose of it. However, according to Robert Earley, biofuels produced from waste oils have yet to take off in China.
“The quality of waste oil biodiesels in China is typically very low, mostly unsuitable for high performance engines of any sort. The feed stocks are usually high in acid and other impurities, meaning that extra processing is needed in the fuel production phase,” he said.
He also noted that the lack of government incentives for waste oil biodiesel programs combined with low market prices for diesel means that the waste oil is most likely to end up back in more profitable products such as food, soap, or cosmetics.
The European Union has banned the use of used cooking oil in animal feed as toxins may accumulate in the animal and be passed on to meat consumers. China still allows the practice.