Traditionally, vegetable oils are "pressed". So when consumers hear that some oils are "leached" with "toxic" chemicals, their instinctive feeling is that "this stuff must be unsafe". And a tea oil leaching varieties have been exposed to "carcinogens" exceeding the standard, more so that the public on this "non-traditional" process of suspicion has reached a new height. What are the carcinogens in tea oil? Why is the traditional "pressed oil" not, and "leaching oil" in the exceeding the standard?

In fact, the "leaching method" of vegetable oil is now the international mainstream. In developed countries, there are few traditional "pressing" plants. The so-called "leaching" is the use of some very volatile organic solvents - the most commonly used is hexane (or a mixture of solvents based on hexane) - to "soak" the crushed oil seeds. Because vegetable oils have a much stronger affinity for these organic solvents, almost all of the oils run into the solvent. After separating the solvent-oil mixture from the oilseed residue, the solvent is removed by heating slightly to obtain the "crude oil". The "crude oil" is further purified and refined to give a pure, clarified vegetable oil. While it is true that organic solvents such as n-hexane are somewhat toxic, because they are so volatile, they hardly remain in the oil at all. Based on the hexane safety standards set by the U.S. Environmental Protection Agency and the possible hexane residue in the leached oil, a person eating dozens of pounds of leached oil a day would not reach a harmful amount.

Leaching requires more complex equipment and processes than pressing, but the advantages are clear. Leaching can extract almost all of the oil from the oilseed, whereas pressing can only yield 70 percent or less, depending on the specific oilseed and pressing process. For food, such a difference can be considered revolutionary.

The "carcinogen" in the "tea oil carcinogen" incident is called "benzo(a)pyrene". It is not a product of modern industry. Any organic combustion, will produce benzo(a)pyrene. Therefore, when the primitive ancestors learned to use fire to roast meat, human beings began to ingest benzo(a)pyrene. Even in natural water sources, there may be some amount of benzo(a)pyrene.

Benzo(a)pyrene is a recognized carcinogen, and high concentrations are capable of inducing cancer. As for the relationship between human intake and cancer risk, there is no clear scientific data. However, since it does not have the slightest value to the human body and people may ingest it from various channels, the requirement of the authorities is that the lower the better. For example, the "target level" of benzo(a)pyrene in the drinking water standard of the United States is zero. However, because of its widespread presence in nature, the zero target cannot be realized. The "actual control standard" set by the U.S. government is no more than 0.2 micrograms per liter of water. It is estimated that a lifetime of drinking water containing this concentration of BaP increases the risk of cancer by an order of magnitude of 1 in 10,000. The safe upper limit of benzo(a)pyrene in cooking oil in China is no more than 10 micrograms per kilogram. Considering that the amount of oil people eat every day is only a few tenths of the amount of water they drink, this "safety standard" is still reasonable.

According to news media reports, the excess of benzo(a)pyrene in tea oil is actually caused by the manufacturer's irregular operation. In order to maximize the extraction of the last drop of oil, the manufacturers of the oil residue for repeated high-temperature heating. Benzo(a)pyrene can be generated from any organic matter at high temperature, and the oil residue is naturally no exception. Finally, these benzo(a)pyrene is "leached" into the oil, so there is a benzo(a)pyrene exceeding the standard of tea oil.

Obviously, the "leaching method" itself does not produce carcinogens, and tea oil itself does not contain carcinogens. The benzo(a)pyrene, which exceeds the national standard permit, is the result of manufacturers' disregard for product quality in order to increase yield. The solution to the problem is not the rejection of tea oil (of course, its misrepresentation and low cost-effectiveness is another matter), not the rejection of "infused oil", nor the return to the traditional oil-pressing workshops, but rather - reasonable and standardized production processes by manufacturers and strong supervision by the competent authorities. The most important thing is that you have to be able to get the best out of it.