Recently, a professional counterfeiter claimed that the Ecuadorian imported frozen South American white shrimp he purchased in the Oriental Selection live broadcast room was found to have excessive sulfur dioxide residue after testing by relevant institutions, and it is speculated that the shrimp medicine “sodium metabisulfite” was added. However, the ingredient list of this white shrimp product only includes South white shrimp, water, and salt, without disclosing the relevant ingredients. The food safety issues involved in the incident have attracted public attention.
What is shrimp medicine?
After catching shrimp, their heads tend to turn black, and the industry commonly uses sodium metabisulfite, also known as “shrimp medicine,” as a preservative. For many years, this substance has been used in the fishing and transportation of shrimp in the sea.
Public information shows that sodium metabisulfite is usually a white or yellow crystalline powder or small crystals, with a strong sulfur dioxide smell and strong reducibility. In the aquaculture industry, this substance can be used as a preservative, but the dosage is strictly controlled.
In the industry, using sulfite (including sodium metabisulfite) as a preservative additive for aquatic products is a common practice and also recommended by the United Nations as a preservative for marine shrimp. However, sodium metabisulfite will produce sulfur dioxide dissolved in water during the decomposition process, resulting in residual sulfur dioxide. Excessive intake in the human body can cause severe gastrointestinal disorders in mild cases, and organ damage in severe cases.
The National Food Safety Standards of the People’s Republic of China for Food Additives (GB 1896.7-2015) and the National Food Safety Standards for the Use of Food Additives of the People’s Republic of China (GB 2760-2014) provide regulations on preservatives and antioxidants such as sodium metabisulfite. The maximum dosage of sodium metabisulfite for fresh aquatic products (limited to shrimp and crab products) and frozen aquatic products and their products is 0.1 g · kg-1 (100 mg · kg-1).
Does sulfur dioxide residue necessarily come from food additives?
Does the sulfur dioxide residue detected in South American white shrimp necessarily come from food additives? not always.
Sulfur dioxide naturally exists in aquatic organisms and has a natural background value. The academic paper “Investigation and Analysis of Residual Sulfur Dioxide in Aquatic Products” points out that sulfur dioxide in aquatic products may come from their own metabolic products. Due to the high protein content in aquatic products, especially those containing thiol proteins, thiol substances are easily produced during their metabolism, which exist in the body of aquatic products and cannot be eliminated during processing, resulting in the detection of SO ₂ during testing. However, this value must be within the standard range.
In many market regulatory notifications, there are occasional examples of exceeding the detection limit of sulfur dioxide residues in seafood. The use of food additives is an indispensable part of the modern food industry, ensuring the beauty, taste, and freshness of food. However, excessive or improper use can pose a potential threat to consumers’ health. Consumers can discern this.
