Recently, after a week-long investigation by the Huaxi Dushi Bao Daily reporter, a secret for Shantou's preservation was unveiled: Adding sodium metabisulfite bleached. On November 27, Shuangliu County law enforcement officers conducted surprise inspections of the processing plants and markets in question. Among the steamed dumplings, one of the samples had been found to have exceeded the standard for sulphur dioxide. What is sodium metabisulfite? Can it be used for food bleaching? We consulted nutritionist Yang Juan.  

Q: What is sodium metabisulfite? Is it a food additive? Can food be added to its solution for food bleaching?

A: Sodium metabisulfite is a white to light yellow, pungent odor crystal. It is a food additive used as a preservative, bleaching agent, and bulking agent in food processing. When sodium metabisulfite is used as a bleaching agent, it is limited to fumigation and cannot be bleached by direct contact with objects such as soaking.  

Q: What kind of health hazards may result from eating foods soaked with sodium metabisulfite?

A: Sodium metabisulfite is artificially synthesized, and the purity cannot reach 100%. There will be some heavy metal residues such as lead and chromium. Long-term consumption may cause excessive heavy metals. Sodium metabisulfite decomposes sulfur dioxide in the air. This compound residue strongly stimulates the body's respiratory and gastric mucosa, causing cough and asthma. Moreover, sodium metabisulfite is easily soluble in water and produces sulfurous acid, which can corrode the intestinal tract.  

Q: What foods are commonly used for the bleaching of sodium metabisulfite? How to judge whether the food bleached by the substance is normal?

A: China's provisions for sodium metabisulfite can be used for candied fruit, biscuits, sugar, rock candy, sugar, candy, glucose, liquid glucose, bamboo shoots, mushrooms and canned mushrooms, the maximum use of 0.45g. It is difficult for the consumer to judge whether the bleached food is normal by the naked eye. It is recommended not to purchase it if it is unusually different from ordinary foods (such as white). (Reporter Tang Gang)