Sources of sulphur and their significance for health

Sulphur-derived preservatives, designated by the E-numbers E220 through E228, are extensively employed within the fruit and vegetable processing sector as potent inhibitors of bacterial proliferation, with a secondary yet notable capacity to suppress the growth of moulds and yeasts. Additionally, these compounds serve as antioxidant agents, safeguarding food products against oxidative degradation. Their antimicrobial efficacy is maximised under acidic conditions characterised by low pH levels, whereas in neutral-pH food matrices, their preservative properties are substantially diminished. The vivid, appealing colouration observed in dried fruits such as apricots and peaches is a direct consequence of sulphur dioxide (E220) application, which concurrently inhibits the enzymatic activity of polyphenol oxidase. This inhibition effectively prevents the enzymatic browning reaction, thereby preserving the deep, natural hues reminiscent of freshly harvested produce. Such attributes confer tangible benefits to manufacturers in terms of product stability and to consumers through enhanced visual and organoleptic quality.

It is important to note that all wines—regardless of type—contain trace amounts of sulphur compounds that form naturally during alcoholic fermentation. Sulphur dioxide (SO₂) and sulphites (IV) play a pivotal role in the production of grape wines, fruit wines, and other wine-based beverages, primarily due to their ability to inhibit the growth of undesirable microorganisms. Additionally, their addition to must or finished wine prevents the oxidation of phenolic compounds, thereby safeguarding against undesirable color changes. Current legal regulations mandate that producers must disclose SO₂ content exceeding 10 mg/dm³ on the product label. The concentration of these compounds in wine depends on multiple factors, including grape quality, pH level, production methods, and storage and aging conditions. According to guidelines, dry wines should not exceed 150–200 mg/dm³ of SO₂ (depending on the wine type), whereas sweet wines may contain up to 400 mg/l, contingent on sugar content. To date, research has not identified adverse health effects from low levels of SO₂ in consumers, provided that established limits are adhered to.

For centuries, sulphur-based compounds have served as indispensable preservatives within the food industry, employed extensively in the processing of semi-finished fruit and vegetable products, the manufacture of jams (refer to Table 1), edible gelatins, mustards, and the stabilization of fermented beverages such as wines and beers. Their primary function lies in the potent inhibition of microbial proliferation, including pathogenic bacteria and mould fungi. Additionally, sulphur dioxide (SO₂) and its saline derivatives are routinely applied during the dehydration of fruits—such as apricots, peaches, bananas, apples, and pears—to mitigate enzymatic browning reactions. **Table 1.** **Permissible maximum levels of sulphur dioxide (SO₂) and its salts in selected food categories** | **Food Product Type** | **Maximum Permitted Concentration [mg/kg or mg/l]** | |------------------------------------|---------------------------------------------------| | Pearled barley groats | 30 | | Peeled potatoes | 50 | | Jams, jellies, marmalades | 50 | | Dried mushrooms | 100 | | Fruit wines | 200 | | Dried apples and pears | 600 | | Dried bananas | 1000 | | Dried apricots, peaches, grapes, plums, figs | 2000 |

The admissible daily intake (ADI) is 0.7 mg/kg of body weight, which means that the average person weighing 70 kg can safely consume 49 mg of sulphuric acid per day, which is of course not the case for people who are sick or over-sensitive to these preservatives. The effects of the compounds labeled with the symbols E220E228 are not indifferent to health, and this is particularly noticeable for those who are oversensitive (510% of asthmatics) and who have the characteristic symptoms of a severe headache, a toxic toxicity to the brain, an acid poisoning to the throat, the administration of a full dose of anabolic acid or the use of any of these products alone.