What are sulfites and why are they in fruit products?
Sulfites, also known as sulphur dioxide ($SO_2$), are chemical compounds used as preservatives in various foods and beverages. Their primary purpose is to extend shelf life by inhibiting microbial growth, such as mold and bacteria. Sulfites also function as an antioxidant, preventing the undesirable browning and discoloration of food, which is especially important for preserving the appearance of dried fruits.
Sulfites in processed and dried fruit
Dried fruit represents one of the most common and concentrated sources of added sulfites. The chemical is used to maintain the fruit's vibrant color and prevent oxidation during the drying process.
- High-sulfite dried fruits: Dried apricots, golden raisins, peaches, apples, and pineapples are examples of light-colored fruits where sulfites are heavily used to preserve their appearance. These products can contain very high levels of sulfites, sometimes reaching thousands of parts per million (ppm).
- Lower-sulfite dried fruits: Naturally dark-colored dried fruits, such as prunes, dates, and figs, are less dependent on sulfites for color preservation and may contain lower levels or be entirely sulfite-free. However, checking the label is always necessary.
Sulfites in fruit juices and wine
Fruit-based beverages are another category where sulfites are prevalent. The presence of sulfites can be due to both natural fermentation and deliberate addition.
- Wine and Cider: Sulfites are a natural byproduct of the fermentation process when yeast converts sugar into alcohol. Additionally, winemakers often add sulfites to protect the wine from oxidation and bacterial spoilage, ensuring stability and freshness. The amount of added sulfite can vary significantly, with sweet wines often having higher levels.
- Fruit Juices: Certain fruit juices, especially bottled lemon and lime juice concentrates, may contain added sulfites. Imported fruit juices can also contain sulfites.
Sulfites in fresh fruits
The story is different for fresh fruits. In 1986, the U.S. Food and Drug Administration (FDA) banned the use of sulfites on fresh produce intended to be eaten raw, like those on salad bars. This was in response to adverse health reactions in sensitive individuals. Generally, fresh fruits are considered sulfite-free from additives.
However, some specific cases of naturally occurring or trace sulfites have been observed in imported fresh fruits. For example, a Canadian study detected sulfites in the rind and, less frequently, the flesh of imported longan, lychee, and cherimoya fruits. For the vast majority of commonly consumed fresh fruits, such as apples, oranges, and bananas, sulfite content is not a concern.
Identifying and avoiding sulfites in fruits
Reading food labels is the most effective way to identify and avoid sulfites, especially in processed fruit products. In many countries, food products containing sulfites at a concentration of 10 ppm (parts per million) or more must declare them on the label. Common sulfite names or E-numbers to look for include:
- Sulphur dioxide (E220)
- Sodium sulphite (E221)
- Sodium bisulphite (E222)
- Sodium metabisulphite (E223)
- Potassium metabisulphite (E224)
- Potassium bisulphite (E228)
Comparison of sulfite content in fruit products
| Fruit Product Type | Sulfite Presence | Reason for Presence | Typical Sulfite Level | Labeling | Recommended for Sensitive Individuals |
|---|---|---|---|---|---|
| Fresh Fruits | Generally absent of additives | N/A (except for natural trace amounts in some imports) | Very low or zero ppm | N/A (additive ban) | Generally safe and recommended |
| Dried Fruits | Often added as a preservative | Prevents browning and spoilage | Can be very high (>1000 ppm) | Labeled if >10 ppm | Avoid, or choose organic/sulfite-free versions |
| Wine and Cider | Natural (fermentation) and added | Preserves freshness, prevents oxidation | Variable (up to 400 ppm for sweet wines) | Must declare “contains sulfites” if >10 ppm | Avoid, or seek wines labeled “no added sulfites” |
| Fruit Juices (Bottled) | Often added as a preservative | Prevents spoilage and microbial growth | Variable, can be high in concentrates | Labeled if >10 ppm | Check labels carefully; choose fresh or organic |
| Maraschino Cherries | Added as a preservative and to bleach | Maintains color and appearance | Variable | Labeled if >10 ppm | Avoid |
Conclusion
For most people, sulfites in food are not a health concern, but those with sensitivities, particularly asthmatics, must be vigilant. When focusing on a nutrition diet, the key distinction lies between fresh and processed fruit. Fresh, raw fruit is generally safe from added sulfites due to regulations, but processed items like dried fruits, wine, and certain juices require careful label checking. Opting for organic dried fruit or making your own preserves can be an effective strategy to avoid added sulfites. By understanding which fruits have sulfites, you can make more informed choices to manage your dietary needs effectively.
Learn more about food sensitivities from the Australasian Society of Clinical Immunology and Allergy.
Keypoints
- Dried fruits are a primary source: Preservatives are heavily used in dried apricots, golden raisins, and other dried fruits to maintain color and extend shelf life.
- Fresh fruits are mostly free of added sulfites: The FDA banned the use of sulfites on fresh produce sold or served raw in the U.S., making fresh fruits generally safe for sensitive individuals.
- Sulfites are in wine and fermented products: They are a natural byproduct of fermentation and are also added by winemakers to preserve freshness.
- Check food labels carefully: Sulfites must be declared on product labels if their concentration is 10 ppm or higher, so reading the ingredient list is crucial.
- Choose organic or homemade options: Opting for organic dried fruits or preparing your own can help you avoid added sulfites.
