Sulfur dioxide

E220, also known as sulfur dioxide, is a chemical compound with the formula SO₂. It is a colourless gas with a pungent, suffocating odour, commonly recognized as the smell of burning sulfur. Sulfur dioxide is highly soluble in water, forming sulfurous acid, and it exhibits strong reducing properties. It is widely used as a preservative and antioxidant in the food and beverage industry due to its ability to inhibit microbial growth and prevent oxidative spoilage.

Origin

Sulfur dioxide can be of both natural and artificial origins. Naturally, it is released into the atmosphere from volcanic eruptions and the burning of organic matter. Industrially, sulfur dioxide is produced primarily through the combustion of sulfur‑containing fossil fuels or by the roasting of sulfide ores in metal extraction processes.

Characteristics

Sulfur dioxide is utilized in food preservation and processing due to its several beneficial properties:

• Preservative: Inhibits the growth of bacteria, molds, and yeasts.
• Antioxidant: Prevents enzymatic and non‑enzymatic browning reactions in foods.
• Colour Stabilization: Maintains the appearance of dried fruits and vegetables.
• Flavour Preservation: Helps in retaining the fresh taste of food products.
• Disinfectant: Used in sanitizing equipment and food surfaces.

Uses in Ultra‑Processed Foods

Sulfur dioxide is extensively used in ultra‑processed foods due to its beneficial properties. Here’s how and why it is used:

• Microbial Inhibition: Sulfur dioxide prevents the growth of bacteria, molds, and yeasts in ultra‑processed foods. Ensuring the safety and extending the shelf life of products such as dried fruits, sauces, and condiments.
• Oxidation Prevention: It acts as a powerful antioxidant, inhibiting oxidative reactions that can cause spoilage. In beverages like wine and beer, sulfur dioxide helps maintain flavour and colour by preventing oxidation.
• Colour Preservation: Sulfur dioxide helps in preserving the natural colour of processed fruits and vegetables. For instance, it keeps dried fruits like apricots and raisins from turning dark, maintaining their appealing visual quality.
• Flavour Retention: By preventing oxidative spoilage, sulfur dioxide helps in retaining the fresh taste of ultra‑processed foods. This is particularly important in products like fruit juices and purees, where flavour integrity is key.
• Texture Stabilization: In baked goods and certain processed foods, sulfur dioxide helps in maintaining texture by preventing microbial growth and spoilage, ensuring that products remain fresh and enjoyable for longer periods.
• Sanitization: Sulfur dioxide is used to sanitize equipment and surfaces in food processing facilities, reducing the risk of contamination and ensuring the overall safety and hygiene of the production environment.
• Shelf Life Extension: Its preservative qualities are critical in extending the shelf life of ultra‑processed foods. This is especially beneficial for products that are stored for long periods or transported over long distances, such as canned foods and packaged snacks.

Health Considerations

While sulfur dioxide is effective in food preservation, its consumption can pose several health risks, particularly in susceptible individuals:

• Respiratory Issues: Exposure to sulfur dioxide can cause respiratory problems, particularly in individuals with asthma or other respiratory conditions. It can trigger bronchoconstriction and asthma attacks.
• Allergic Reactions: Some individuals may experience allergic reactions, including skin rashes, itching, and hives. Sulfite sensitivity is more common in people with asthma.
• Gastrointestinal Issues: Ingestion of high levels of sulfur dioxide can cause gastrointestinal discomfort, including nausea, vomiting, and diarrhea.

Due to these potential risks, regulatory bodies such as the U.S. Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA) have set limits on the allowable concentration of sulfur dioxide in food products. It is also mandatory to label foods containing sulfur dioxide to inform consumers.

References

1. European Food Safety Authority (EFSA). (2016). Re‑evaluation of sulfur dioxide (E 220) as a food additive. Retrieved from EFSA Journal
2. Health Canada. (2021). Sulphites in Food. Retrieved from Health Canada website
3. Stevenson, D. D., & Simon, R. A. (1981). Sensitivity to ingested metabisulfite in asthmatic subjects. Journal of Allergy and Clinical Immunology, 68(1), 26‑32. Retrieved from PubMed
4. Lester, M. R. (1995). Sulfite sensitivity: significance in human health. Journal of the American College of Nutrition, 14(3), 229–232. https://doi.org/10.1080/07315724.1995.10718500
5. Vally, H., & Misso, N. L. (2012). Adverse reactions to the sulphite additives. Clinical and Experimental Allergy, 42(2), 164‑172. doi:10.1111/j.1365‑2222.2011.03943.x