Why is it possible that soy sauce contains 3-MCPD?

       This has to do with the production process of soy sauce, whose main ingredient is vegetable protein of soybeans that is fermented or acid-hydrolyzed into small particles of amino acids, aldehydes, ketones and organic acids. Common salt, food coloring and flavoring agent are then added to the mixture of soybeans to give its taste. So far, soy sauce production can be broadly divided into brewing by microbial fermentation, rapid brewing and mixed method.

       Traditionally, soy sauce is produced by microbial fermentation of soybeans and other raw ingredients under appropriate conditions, during which proteins are broken down to become its flavor components. The most traditional way of brewing soy sauce is natural fermentation in large urns under the sun that takes approximately six months to complete the process. More contemporary way of its production is by fermentation under a controlled warm environment that takes 10 to 30 days.

      Since traditional brewing method is time-consuming and costly, rapid brewing and mixed method have been introduced as alternative options, in which hydrochloric acid is added to facilitate hydrolysis of vegetable protein to save the time taken for its hydrolysis by microbial enzymes. But during the production of acid-hydrolyzed protein, the reaction of hydrochloric acid with the residual fats and oils in vegetable protein over heating may form 3-MCPD.

       3-MCPD is a naturally occurring contaminant formed during production, cooking and other processing activities of soy sauce. In traditional brewing of soy sauce by fermentation in which no hydrochloric acid is added, no 3-MCPD is formed.

What is 3-MCPD?

       It is a contaminant formed during food manufacturing, cooking and other processing activities. In the case of soy sauce production by rapid fermentation or mixed method, hydrochloric acid is added to facilitate hydrolysis of vegetable proteins. But during the production of acid-hydrolyzed protein, the reaction of hydrochloric acid with the residual fats and oils in vegetable proteins over heating may form 3-MCPD.

What are the impacts of 3-MCPD on health?

       According to the report of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) of the United Nations in 2001, it concluded that 3-MCPD is not carcinogenic to humans and not genotoxic in vivo in experimental animals. But JECFA recommends the maximum tolerable daily intake of 3-MCPD to be 2mg/kg body weight. Generally, when soy sauce is consumed as a seasoning, the amount of its intake is of low concern for human health.

How to choose soy sauce safely?

• Purchase soy sauce from reputable shops with good hygiene condition;
• Careful reading about the label on the packaging and the specified expiry date;
• Check whether packaging of soy sauce is intact and without damage;
• Keep soy sauce in a cool and well-ventilated place or under cold storage;
• In case the soy sauce has an abnormal taste or repulsive smell, do not buy or consume it;
• Be a smart consumer. Do not buy or consume any soy sauce if doubtful about its safety on health. 

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