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Is your soy sauce safe?

by Junelyn S. de la Rosa


toyoA NO answer would probably send the whole country into a tailspin since almost all Filipino dishes are flavored with the versatile soy sauce. While this issue was relatively resolved a couple of years ago when the local Bureau of Food and Drugs (BFAD) declared that all BFAD-registered soy sauce products are safe, there is still a lingering paranoia that some sauces might not be safe since some countries banned our export soy sauce products a couple of years ago.

To solve the problem, scientists from the Department of Chemistry at the Ateneo de Manila University developed a simple, accurate, and inexpensive analytical method to test whether soy sauce and other sauces contain high levels of 3-MCPD- a dreaded cancer-causing chemical.

What is 3-MCPD?

3-MPCD or 3- monochloropropane-1, 2-diol belongs to a group of chemical contaminants known as chloropropanols. 3-MCPD can be found in some soy sauces that are produced through a process called “acid hydrolysis”. Acid hydrolysis is a modern processing method used to treat proteins such as soya in making soy sauces. However, soy sauces produced using the traditional (natural) fermentation process are safe since they do not contain the chloropropanols.

A study conducted by Australia’s New Zealand Food Authority (ANZFA) reported that two-thirds of the samples containing 3-MCPD also contained smaller amounts of another chloropropanol (1,2-DCP). While these substances are present in very minute amounts in many foods and food ingredients, it has been found that they can cause cancer in laboratory animals fed large amounts over their lifetime.

Scientists said that there is no need to fear occasional consumption of contaminated soy sauces but that regular consumption over long periods of time can be a potential cause of cancer.

Europe’s Scientific Committee for Food said that a person could consume only 0.002 mg/kg bodyweight/day of 3-MCPD over a lifetime without harm to health. Further studies stated that safe consumption levels for 3-MCPD can be set because it does not directly affect genetic material. However, people should be more careful of 1,3-DCP since it is harmful to genetic material. Scientists said that cancer found in reproductive cells caused by 1.3-DCP could be passed on to children.

Banned sauces

In 2001, various studies abroad reported that popular sauce brands contain unsafe levels of 3-MCPD. ANZFA found that some sauces’ 3-MCPD levels were above 3.5 milligrams per kilogram which was way above the level of safe use. Some soy sauce products that were banned abroad included: Amoy seafood soy sauce from Hong Kong, Gia Minh seasoning soy sauce from Vietnam, Kimlan soy sauce and dark soy sauce from Taiwan, Knorr seasoning from Hong Kong, President creamy soy sauce from Taiwan, Silver Swan soy sauce from the Philippines, Ta Tun soy bean sauce from Taiwan, Tau Vi Yeu seasoning sauce and Soya bean sauce from Vietnam, Zu Miao Fo Shan soy superior sauce and Mushroom soy sauce from China and Golden Mountain and Wanjashan Soy Sauces.

Other soy sauces that were removed from the shelves were: Golden Mountain soya bean sauce, King Imperial dark soy sauce, Pearl River Bridge mushroom soy sauce, Jammy Chai pure soy sauce, XO soy sauce, Golden Mark superiro soy sauce, Lee Kum Kee oyster sauce, Tung Chun gold label soy sauce, Golden Swan superior dark soy sauce, Golden Mountain Seasoning sauce, Pearl River Bridge shrimp flavor soy sauce, Pearl River Bridge superior soy sauce, Kimlan Lo Chau, Lee Kum Kee chicken marinade, Sinsin oyster sauce.

Testing for 3-MCPD

To test for the presence of 3-MCPD, the scientists from Ateneo de Manila University have developed an analytical method using gas chromatography-mass spectrometry at a concentration range of 1-5000 ng g-1 using 4-heptanone as a derivatizing ketone and 3-MCPD as an internal standard. Gas chromatography is a method of separating the volatile constituents of a substance by means of gas, for the purpose of analysis. Mass spectrometry, on the other hand, is a method of identifying the chemical constitution of a substance by means of the separation of gaseous ions according to their differing mass and charge. The scientists said this method is safe, simple, and effective. Finally, they are optimistic that this method can be used in the near future to make sure that soy sauce products found in the shelves are safe.

Development of an analytical method for 3-monochloropropane-1-2,-diol in soy sauce using 4-heptanone as derivatizing agent by Fabian Dayrit and Milady Niñonuevo of the Department of Chemistry, Ateneo de Manila University, Loyola Heights, Quezon City