Sulfur dioxide (SO2) is a chemical compound widely used as a preservative in the food industry. The Centre for Food Safety (CFS) recently identified instances where prepackaged dates contained excessive levels of sulfur dioxide without proper labeling, leading to food alerts and recalls. This article delves into the use of sulfur dioxide in food, its safety, and regulations surrounding it.
Why is Sulfur Dioxide Used in Food?
Sulfur dioxide has been a staple in food production for years due to its versatile properties. But what exactly does it do? It functions primarily as a preservative in various food and beverage products like dried fruits, pickled vegetables, fruit juices, and wines.
SO2 inhibits the growth of microorganisms such as yeasts, bacteria, and molds. It works by penetrating the cell walls of these microbes and disrupting their normal functions, effectively preventing spoilage and extending the shelf life of food products.
Beyond its antimicrobial properties, sulfur dioxide acts as an antioxidant, preventing browning caused by oxidation in foods, especially dried fruits and vegetables. This helps maintain the products’ appearance and color. Without it, light-colored fruits like dried apricots can quickly darken upon air exposure.
Sulfur dioxide is also commonly used in winemaking to prevent spoilage and oxidation, preserving the wine’s quality and freshness.
Figure 1: Sulfur dioxide is used in a variety of foods and beverages.
Is Sulfur Dioxide in Food Safe to Consume?
Like all food additives, sulfur dioxide undergoes extensive safety assessments before being deemed safe for consumption. The Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA), a leading international food safety authority, has evaluated its safety.
When used according to Good Manufacturing Practice (GMP), which means using the minimum amount necessary to achieve the desired technological effect, sulfur dioxide is considered safe for normal consumption.
However, some individuals are hypersensitive to sulfur dioxide and may experience allergic reactions, including breathing difficulties, headaches, and nausea, after consuming foods containing it.
Sulfur Dioxide Regulations in Hong Kong
In Hong Kong, the use of sulfur dioxide as a preservative and antioxidant is governed by the Preservatives in Food Regulation (Cap. 132BD), which specifies its permitted use and levels in certain foods.
According to the Food and Drugs (Composition and Labelling) Regulations (Cap. 132W), prepackaged foods containing sulfur dioxide must declare its presence on the ingredient list, including its functional class (i.e., preservative) and specific name (sulfur dioxide, sulfites, or sulfite derivatives) or its International Numbering System (INS) identification number (220-228 and 539).
Furthermore, because sulfur dioxide is a potential allergen, these regulations mandate that all prepackaged foods with a sulfite concentration of 10 parts per million or more must specify the functional class and name of the sulfite in the ingredient list.
Foods in bulk packages that are re-packaged into smaller units for retail must also declare the presence of sulfur dioxide, if any, on both the bulk and smaller packages’ labels. When in doubt, checking with suppliers for detailed ingredient information is essential.
Clear labeling is crucial for consumers to identify and avoid sulfur dioxide if they are sensitive to it.
Key Takeaways Regarding Sulfur Dioxide
- Sulfur dioxide functions as a preservative and antioxidant in various foods, such as dried fruits, to extend shelf life and prevent browning.
- In Hong Kong, the Preservatives in Food Regulation governs the use of sulfur dioxide.
- The Food and Drugs (Composition and Labelling) Regulations require proper labeling of sulfur dioxide.
Advice for Consumers
- Sulfur dioxide has undergone thorough safety evaluations and has a long history of use as a food additive in many countries.
- If you are susceptible to sulfur dioxide, carefully check food labels before purchasing and avoid products containing it.
Advice for the Food Industry
- Use sulfur dioxide according to the Preservatives in Food Regulation and Good Manufacturing Practices.
- Clearly and accurately declare the presence of sulfur dioxide on labels in compliance with the Food and Drugs (Composition and Labelling) Regulations.
- Always declare the presence of sulfur dioxide on labels for both bulk and smaller retail packages.
