With the inefficiency of current techniques for detecting and identifying the use of illegal cooking oil in China, there is an urgent need to improve kitchen waste recycling procedures to prevent the continued use of such oil in food production, a leading food expert has said.

He Dongping, of Wuhan Polytechnic University, who is leading a study on waste oil.

He Dongping, a professor of food science engineering at Wuhan Polytechnic University (WHPU), revealed last Thursday that one in every 10 meals in the country might have been cooked with dirty oil based on an ongoing study.

The revelation has raised widespread alarm. The State Food and Drug Administration on Thursday issued an emergency notice to restaurants nationwide, warning them against recycling oil.

In an interview with China Daily over the weekend, He said his research team at WHPU is working on developing a method for detecting and identifying illegal cooking oil, which is a difficult task.

"It's hard to tell the difference between illegal cooking oil and its ordinary counterparts just by looking and smelling," said He.

In addition to an effective method of detection having yet to be found, the difficulty is compounded once the illegal oil has been blended into ordinary ones.

The "illegal cooking oil" is usually made from discarded kitchen waste that has been refined. Although it looks clean and clear, it actually contains toxic substances, including "aflatoxin", which can cause cancer.

"The country's underground oil refining businesses have grown pretty mature. There is a whole set of procedures for producing illegal cooking oil," He explained.

In the current situation, preventing of the use of illegal cooking oil should start at its source, kitchen waste, He said.

"The first step is to ensure an official, standardized collection of kitchen waste," he recommended.

In the interim, the use of illegal cooking oil continues to be sustained by its high profitability.

An investigation in Wuhan showed few restaurants are willing to hire the city's sanitation workers for kitchen waste collection.

The owner of a restaurant in the Wuchang district of Wuhan, capital of Central China's Hubei province, last Friday told China Daily he serves at least 50 tables a day, which produces two big barrels of kitchen waste.

According to the restaurateur, the waste could be collected and recycled by sanitation workers, but an official with the Wuhan urban management bureau told China Daily that sanitation workers never collect waste from restaurants.

"The restaurants have to pay a certain fee if they hire the city's sanitation workers, whereas selling kitchen waste to private parties can make up to 10,000 yuan ($1,500) every year," Zeng Wei, director of the Wuhan Airui Biodiesel Company, told Xinhua News Agency on Saturday.

According to Zeng, many restaurants contract out their kitchen waste collection to private parties, a stable set-up in which there is no room for the entrance of an outside party.

Under the arrangement, a large restaurant is capable of making 2 million yuan per year just by selling its kitchen waste, Xinhua reported.

As a country with a prosperous restaurant business, the amount of kitchen waste produced on a daily basis in China is quite large, forming 40 percent of a city's total waste, He told China Daily.

He said Chinese cities fall into five categories for the amount of kitchen waste they produce. First level cities (Beijing and Shanghai) produce 1,000 to 1,500 tons of waste per day; second level cities (such as Wuhan) produce 500 to 1,000 tons; third level cities (of which Qingdao and Ningbo are examples) produce 200 to 500 tons; fourth level cities (like Xiangfan in Hubei) produce 100 to 200 tons; and fifth level cities (which are primarily at the county level) produce less than 100 tons, according to He.

Refining 1 ton of the waste would produce 130 kg of illegal cooking oil. With its price being half that of ordinary cooking oil, a profit of 1.5 to 2 billion yuan is produced in the entire illegal cooking oil business in the country every year, He said.

"The profit margin is almost 200 percent. It's easy to understand why the business is so hot."