Publicizing information on tests for gossypol

By Chang Yeh-shen 張葉森  / 

Fri, Nov 22, 2013 - Page 8

On Oct. 24 the Northern Taiwan Society issued a statement pointing out that ordinary cottonseed oil contains between 0.5 percent and 0.7 percent free gossypol. When cottonseed oil is pressed, some gossypol is dissolved in the oil. There are three types, or tautomers, of gossypol — phenol-aldehyde, lactone and cyclic ketone types — which are interconvertible under certain conditions. Gossypol can be analyzed by high-performance liquid chromatography (HPLC), and experts around the world use phenol-aldehyde gossypol as the reference standard for such tests.

Taiwan’s Ministry of Health and Welfare has appointed the Food Industry Research and Development Institute to conduct gossypol tests, but more than half a month later, there is still no answer as to what reference standard is being used in these tests.

Soon after the current uproar over cooking oils broke out, the ministry announced that gossypol content was “not detected” in local tests of refined and unrefined cottonseed oil, based on a minimum quantity of 1 part per million (ppm) that can be detected using HPLC.

Gossypol can occur as free gossypol or bound gossypol. Free gossypol is generally considered to be toxic to animals, whereas bound gossypol generally cannot be absorbed by farm animals and is widely considered to be nontoxic. However, quite a lot of research done in recent years indicates that some bound gossypol can detach to form free gossypol and have toxic effects. It is a fact that if gossypol is present in animal feed, it is not good for the growth of the animals that eat it.

Council of Agriculture regulations on gossypol content in animal feed state that gossypol residues should not exceed 0.04 percent (400ppm) in cottonseed meal intended for use in animal feed or 10ppm in finished feed. Some Taiwanese companies import cottonseed pellets for use in animal feed. The council announced that the gossypol content of the first lot of cottonseed to be tested in the nation was 3,800ppm, and that if this cottonseed is added to animal feed so that it makes up 2 to 7 percent of the feed, then the gossypol content of the feed will be between 100ppm and 350ppm.

The council said that the higher and lower figures are both lower than the maximum gossypol content of 5,000ppm in cottonseed material and 500ppm in finished feed allowed under EU regulations. At this point we might well ask why the council has its own set of established standards and yet is not referring to them.

The Northern Taiwan Society is concerned about how much gossypol residue there actually is in cooking oil and animal feed, and about what kind of tests are being used to detect and measure it. It would be good if the ministry and the council could answer these questions and make the information public, so that Taiwanese can have peace of mind about what they and domestic animals are eating.

Chang Yeh-shen is a physician and chairman of the Northern Taiwan Society.

Translated by Julian Clegg