Dried Fruit
This is the highest-sulphite food category. Sulfur dioxide is used to preserve color and prevent browning in dried apricots, golden raisins, dried peaches, dried pears, dried apples, dried pineapple, and dried mango. The mechanism is straightforward: sulfur dioxide inhibits enzymatic browning by inactivating polyphenol oxidase, the enzyme that turns cut fruit brown. Without sulphites, dried apricots turn dark brown within hours of drying.
Light-colored dried fruits typically contain sulphites. Dark-colored dried fruits — raisins (dark Thompson seedless), prunes, figs, dates — generally do not, because browning is already part of their natural color profile.
Specific guidance: Dried apricots are consistently the highest-sulphite dried fruit (often exceeding 1,000 ppm). Golden raisins are sulfured; regular dark raisins are not. Sulfur-free dried fruit exists and is labeled "unsulfured" or "sulphite-free." Organic dried fruit may still contain sulphites per USDA organic regulations, which permit sulfur dioxide as a processing aid for dried fruit.
Wine, Beer, and Cider
Sulphites are a natural byproduct of fermentation — yeast produces small amounts of sulfur dioxide during alcoholic fermentation — so all wine contains some endogenous sulphite. The amounts that trigger concern are the added sulphites. Winemakers add potassium metabisulfite or sulfur dioxide at multiple stages — crush, fermentation arrest, barrel aging, and bottling — to prevent oxidation and microbial spoilage. The result is that commercial wine almost always exceeds the 10 ppm threshold.
White wines and sweet wines contain more sulphites than red wines. Red wine's tannins and anthocyanins provide natural antioxidant protection, reducing the need for added sulfur dioxide. Organic wines undergo the same fermentation biology but use lower or zero added sulphite at bottling. The USDA organic standard for wine permits sulfites at lower maximums than conventional wine, but organic wine is not sulfite-free.
Beer and cider are lower-sulphite beverages than wine but are not sulfite-free. Beer typically contains sulfites at concentrations below 50 ppm. Cider varies by producer; sweet ciders use sulfites to arrest fermentation and retain residual sugar.
Since the late 1980s, US wine labels have been required to carry "Contains Sulfites" when sulfur dioxide or sulfiting agents are present above 10 ppm. EU wine labels adopted the same requirement in 2005.
Frozen and Refrigerated Potatoes
Frozen French fries, frozen hash browns, frozen potato wedges, and refrigerated pre-cut potato products use sodium metabisulfite to prevent enzymatic browning. Fresh-cut potatoes oxidize within minutes of being peeled and sliced. The sulphite treatment keeps them visually appealing through freezing, distribution, and cooking. The finished sulphite level in commercially processed frozen potato products varies by manufacturer and process, but the category should be treated as high-sulphite by default.
Shrimp, Prawns, and Crustaceans
Sodium metabisulfite is applied to shrimp, prawns, and lobster to prevent melanosis — black spot formation on the shell and flesh after harvest. Melanosis is a harmless enzymatic reaction, but it makes the product unsellable, and the commercial response is near-universal sulphite treatment of fresh and frozen crustaceans.
Wild-caught shrimp are more heavily sulfured than farmed shrimp because they spend longer in transit from harvest to processing. The 10 ppm threshold means some treated shrimp may test below 10 ppm and carry no declaration. For sulphite-sensitive individuals, this makes shrimp a risk category where the label may not capture the full exposure.
Bottled Lemon and Lime Juice
This is one of the most commonly overlooked sulphite sources. Bottled lemon juice and lime juice — the kind sold in plastic squeeze bottles and small glass jars in the juice aisle or baking section — are almost universally sulfured to prevent browning and maintain flavor. Fresh-squeezed lemon and lime juice contain no sulphites. The bottled version is a different product entirely.
Pickled Foods, Sauerkraut, and Fermented Vegetables
Sulphites are sometimes used in the production of sauerkraut, pickled onions, pickled peppers, and other fermented vegetable products, both to control fermentation and to preserve color. Not all brands use them; ingredient lists must be checked individually. This is a high-variance category.
Molasses, Corn Syrup, and Sweeteners
Sulfur dioxide is used in sugar refining as a bleaching agent and in molasses production. Light molasses (first-boil) has lower sulfite levels; blackstrap molasses (third-boil) has higher levels because sulfur dioxide is applied at each boil. Corn syrup may also carry residual sulfites from the steeping and refining process.
Maraschino Cherries, Fruit Fillings, and Preserves
Maraschino cherries are bleached with sulfur dioxide before being flavored and colored. The bleaching step produces high local sulfite concentrations. Fruit pie fillings, fruit preserves, jams, and jellies may use sulfites as preservatives, though pectin-based preservation has reduced the frequency of this practice. Check labels individually.
Salad Bar and Deli Items (Post-1986 Ban Context)
The 1986 ban prohibits sulphites on fresh raw produce. Fresh lettuce, fresh cut vegetables, and guacamole should be sulfite-free by federal law. Pre-packaged salads with dressing included, and some refrigerated guacamole and avocado products, may contain sulfites in the dressing or preservative component. The distinction is between fresh (banned) and processed/preserved (not banned but must be labeled above 10 ppm).
Dough Products
Sodium metabisulfite is used as a dough conditioner in some frozen dough, pizza dough, and commercial bread production. It relaxes gluten and improves workability. Not all dough products use it, and the levels in finished baked goods usually drop below 10 ppm during baking, but sensitive individuals should be aware of the possibility.
