Soaking dried fruit in warm or hot water is the most effective home method for reducing sulfur dioxide, and it can remove a significant portion of the preservative in as little as 5 to 10 minutes. Sulfur dioxide (SO₂) is highly water-soluble, so it leaches out of fruit tissue and into the surrounding liquid. The warmer the water and the longer the soak, the more sulfite you remove.
Why Dried Fruit Contains Sulfur Dioxide
Sulfur dioxide prevents browning and inhibits mold growth during drying and storage. It’s the reason sulfured apricots stay bright orange instead of turning dark brown, and why golden raisins look so different from their unsulfured counterparts. Dried apricots, peaches, grapes, prunes, and figs can legally contain up to 2,000 parts per million (ppm) of sulfites in the European Union. Dried apples and pears are permitted up to 600 ppm. These are among the highest sulfite levels allowed in any food category.
On ingredient labels, sulfur dioxide may appear under its own name or as one of several related compounds: sodium sulfite (E 221), sodium bisulfite (E 222), sodium metabisulfite (E 223), potassium metabisulfite (E 224), calcium sulfite (E 226), calcium bisulfite (E 227), or potassium bisulfite (E 228). In the U.S., any food containing 10 ppm or more of sulfites must declare it on the label.
How to Tell if Your Dried Fruit Has Sulfites
Color is the easiest visual indicator. Sulfured apricots are vivid orange. Unsulfured apricots are dark brown, almost chocolatey in appearance. The same pattern holds for other fruits: sulfured versions retain their fresh, bright color, while untreated versions darken considerably during drying. If the package doesn’t list sulfites but the fruit looks unnaturally bright, check the ingredients list again carefully for any of the E-number additives listed above.
Soaking in Water
Because sulfur dioxide dissolves readily in water, a simple soak pulls it out of the fruit. Here’s how to do it effectively:
- Warm water soak (easiest method): Place the dried fruit in a bowl and cover it with warm water, around 40 to 50°C (105 to 120°F). Let it sit for 15 to 30 minutes, stirring occasionally. Drain and rinse thoroughly. This is gentle enough to preserve texture while removing a substantial amount of sulfite.
- Hot water soak (faster removal): Use water just off the boil. Submerge the fruit for 5 to 10 minutes. The higher temperature speeds up the release of SO₂ into the water. Drain, rinse, and pat dry. The fruit will soften more with this method, which works well if you’re using it in baking or cooking.
- Repeated soaking: For maximum reduction, soak the fruit once, discard the water, then soak again in fresh water. Each cycle pulls additional sulfite from the fruit tissue.
Always discard the soaking water. That’s where the sulfites end up. Rinsing the fruit under running water after draining removes residual sulfite clinging to the surface.
Blanching for Quick Reduction
A brief blanch in boiling water is another option, especially for firmer dried fruits. Plunge the fruit into boiling water for 30 seconds to a minute, then transfer it to cold water to stop the cooking process. This short, intense heat exposure drives off sulfur dioxide as a gas (SO₂ is volatile at high temperatures) while also dissolving it into the water. The trade-off is texture: blanching softens fruit more than a warm soak, so it works best when you plan to cook or blend the fruit afterward.
Steam Treatment
Steaming dried fruit over boiling water for 5 to 10 minutes also reduces sulfite levels. The heat causes SO₂ to volatilize off the fruit surface. This method adds less water to the fruit than soaking does, so it preserves a chewier texture. Spread the fruit in a single layer on a steamer basket, cover, and let the steam do the work. You won’t remove as much sulfite as a full water soak, but it’s a useful compromise when you want the fruit to stay relatively dry.
What You Can’t Fully Remove
No home method eliminates 100% of sulfur dioxide. Some SO₂ binds chemically to sugars and other compounds in the fruit, forming what chemists call “bound sulfites.” These don’t dissolve out in water as easily as free sulfites do. Soaking and blanching primarily target free and loosely bound sulfites, which are also the forms most likely to trigger reactions in sensitive people. If you need to avoid sulfites entirely, buying unsulfured dried fruit is the only reliable option.
Choosing Unsulfured Dried Fruit
Organic dried fruit is almost always sulfite-free, since sulfur dioxide is not permitted in organic production in most countries. Instead, producers use ascorbic acid (vitamin C), citric acid, or lemon juice as pretreatments to slow browning and inhibit bacteria. These alternatives are less effective at preserving color, which is why organic dried apricots and mangoes tend to look darker and less glossy than their conventional counterparts.
Unsulfured fruit also has a shorter shelf life. Without SO₂ suppressing oxidation and microbial growth, the fruit darkens faster and can develop off-flavors within a few months. Store unsulfured dried fruit in airtight containers in a cool, dark place, or refrigerate it to extend its usable life.
Who Needs to Worry About Sulfites
Most people metabolize sulfites without any trouble. The group most at risk is people with asthma, particularly those with severe or poorly controlled symptoms. Sulfite sensitivity can trigger wheezing, chest tightness, and in rare cases, anaphylaxis. Foods containing 100 ppm or more of SO₂ are classified as high-sulfite foods, and dried fruit often exceeds that threshold by a wide margin.
The EU requires labeling on any food with sulfite levels above 10 ppm, and U.S. regulations set the same 10 ppm detection threshold for mandatory disclosure. If you know you’re sensitive, reading labels is essential, but also know that soaking and rinsing your dried fruit can meaningfully lower your exposure even if it doesn’t eliminate it completely.
Does Removing Sulfites Affect Nutrition?
Sulfur dioxide is known to destroy thiamine (vitamin B1) through a chemical reaction that breaks the vitamin into inactive fragments. In practice, though, dried fruit is not a major source of thiamine, so this interaction matters more in foods like grains and meats. Studies in human subjects given sulfite alongside a normal diet found no measurable effect on blood thiamine levels, urinary thiamine excretion, or the activity of thiamine-dependent enzymes. The concern is more theoretical than practical for people eating a varied diet.
Soaking does leach out some water-soluble vitamins and minerals along with the sulfites. Vitamin C and some B vitamins will partially dissolve into the soaking water. If you’re soaking fruit specifically for nutrition, keep the soak time short and the water temperature moderate to minimize these losses. For most people, the small nutritional trade-off is worth the reduction in sulfite exposure.