Summary - Sulfites
Sulfites (sulphites) are inorganic salts that contain the sulfite ion SO2-3. These compounds have antioxidant and preservative properties. They occur naturally in some foods and beverages as a result of fermentation, such as in beer and wine. Sulfites are also regulated food additives used as preservatives to maintain food colour and prolong shelf-life, prevent the growth of micro-organisms, and to maintain the potency of certain medications. Sulfites are used to bleach food starches (e.g. potato) and are also used in the production of some food packaging materials (e.g. cellophane). In fresh fruits and vegetables, sulfites prevent an enzyme called polyphenol oxidase (PPO) from working properly in order to prevent brown pigment formation (Sapers, 1993; Sayavedra-Soto and Montgomery, 1986). Sulfites are thought to inhibit browning by acting as a reducing agent that combines with the ortho-quinones and converts them back to colorless diphenols. They're used to keep dried fruit like apricots from turning brown and to prevent unwanted bacteria from spoiling the wine.
The list of food and products that often contain sulfites is long. It includes wine, beer, cider, fruit and vegetable juices and concentrates, canned and frozen fruits and vegetables, cereal, cornmeal, cornstarch, crackers and muesli, condiments (coleslaw, horseradish, ketchup, mustard, pickles, relish and sauerkraut), dehydrated, mashed, peeled and pre-cut potatoes, dried fruits and vegetables, dried herbs, spices and teas, fresh grapes, starches, vinegar and wine vinegar, sugar syrups, tomato pastes, pulps and purees, fruit fillings and syrups, gelatin, jams, jellies, preserves, marmalade, molasses, pectin, glazed fruits.
The sulfites that can be added to foods as food additives are:
Sodium bisulphite (sodium hydrogen sulphite)
Sulfites are counted among the top food allergens. They don't cause problems for the vast majority of people but asthmatics that are steroid-dependent or have a great degree of airway hyper reactivity may be at an increased risk of having a reaction to a sulfite containing food (Lester, 1995). Varying degrees of bronchospasm, angiodema, urticaria, nausea, abdominal cramping, and diarrhea are commonly reported (Knodel, 1997). Adverse reactions to sulfites in non-asthmatics are extremely rare. These reactions can range from very mild to quite severe. In very rare cases, a reaction can be life-threatening
Labeling product containing sulphites, sulfites, sulphur dioxide or sulfur dioxide is a subject of
EU REGULATION No 579/2012, applicable on June 29th 2012.