Sulphite

Sulphite is a chemical species with the general formula [SO3]n2− or SO3 2−. It is a salt or ester of sulfurous acid. Common examples include sodium sulphite (Na2SO3) and potassium sulphite (K2SO3). Sulphites are often found as solids and are typically soluble in water. In aqueous solutions, sulphite exists in equilibrium with bisulphite (HSO3−) and sulfurous acid (H2SO3).

Sulphites have a variety of industrial applications. They are frequently used as reducing agents, disinfectants, and preservatives. In the food industry, sulphites are added to foods and beverages to prevent oxidation, inhibit microbial growth, and maintain color. This is why they are often found in dried fruits, wine, and some processed meats. The use of sulphites in food is regulated, and products containing them are usually labeled.

Some individuals can experience adverse reactions to sulphites, particularly those with asthma. These reactions can range from mild symptoms like hives and digestive upset to severe respiratory distress. For this reason, food labeling laws in many countries require the declaration of sulphite content if it exceeds certain thresholds.