Sulphur in food

Sulphur is an essential mineral that we have to take in with our food. This usually happens without any problems and without us paying any special attention to it. In fact, we are so well supplied with this mineral that, unlike other minerals, there is no guideline for the recommended daily intake. However, in addition to naturally occurring sulphur, sulphur-containing compounds are added to some foods as a preservative. Which foods are good natural sources of sulphur and where is sulphur used as a preservative?

Many foods that we eat every day contain sulphur. With this, we are usually well supplied and do not need to worry about a deficiency.

Protein-rich foods in particular have a high sulphur content: Milk, eggs, yoghurt, curd cheese, fish, mussels and meat provide a lot of sulphur. But nuts, rapeseed, mustard, onions and garlic also contribute to the supply. Deficiency symptoms are not to be expected with a sensible diet, nor is a surplus likely.

As early as the late Middle Ages, sulphur compounds were used to preserve food. For example, the Greeks and Romans preserved their wine with sulphur to prevent the wine from fermenting into vinegar.

Today, there are several sulphur-containing preservatives labelled with E numbers. E220 stands for sulphur dioxide, E221 to E224 and E226 to E228 for the sulphites. Sulphites are the salts of sulphurous acid, here in the form of sodium, potassium and calcium compounds. They block the growth of fungal and bacterial cultures and also prevent colourings, vitamins and flavours from degrading on contact with oxygen. This keeps the products fresh longer and prevents them from turning brown. Different maximum permitted levels of sulphur dioxide apply to different foods.

Sulphur dioxide destroys vitamin B1. Therefore, it must not be added to staple foods that are rich in vitamin B1.

Sulphur-containing preservatives are often used in the following foods:

Today, almost all wines are sulphurised. In most cases, the dosage is so low that the sulphur cannot be smelled or tasted. Health concerns can also be ruled out. Nevertheless, the addition of sulphur must be declared on the label: as soon as a wine contains 10 milligrams of sulphur dioxide per litre, labelling, for example in the form of "contains sulphites", is mandatory.

The wine is sulphurised at several points in the production process: at the mash stage, after fermentation and before bottling. Some of the sulphur combines with ingredients of the wine and is then bound. The bound sulphur is not perceptible in smell and taste and has no health consequences. The free sulphur is present as free sulphurous acid or its salt, as sulphite. In high concentrations, this free sulphur can impair the smell and taste of the wine and cause health complaints. The EU has defined maximum sulphite values for all types of wine, ranging from 150 to 400 milligrams of sulphur dioxide per litre, depending on the type of wine. The sweeter a wine is, the higher its sulphur requirement, so the maximum allowable level varies.

In some circles, the sulphurisation of wine is strongly criticised. Yet it is a traditional and very effective process and allows the wine to be stored for longer.

Mangoes, apricots, plums or apple rings: dried fruit is diverse and stimulates the appetite with its bright colours. To ensure that dried fruits retain their beautiful colours, they are treated with sulphur dioxide. It acts against yeasts, fungi and bacteria and thus prevents the fruit from turning brown. In addition, the degradation of flavours and vitamins is counteracted. For most people, eating dried fruit is harmless because an enzyme produced naturally in the body ensures that sulphur dioxide is broken down quickly. Depending on the type of fruit, dried fruit may contain a maximum of 500 to 2000 milligrams of sulphur dioxide per kilogram.

Surely you know the little jars of grated horseradish or creamed horseradish as a delicious seasoning for roast beef or smoked fish. But the sulphur compound E223 is often added to horseradish as a preservative and antioxidant. This is because the spice can be kept for a long time even after opening and does not discolour darkly. Horseradish preparations may contain a maximum of 800 milligrams of sulphur dioxide per kilogram.

Mashed potatoes, chips and co: these products are also preserved with sulphur dioxide and sulphites. Peeled potatoes for catering remain durable and retain their yellow colour, but often at the expense of taste; they become hard and taste soapy. Dry potato products may contain a maximum of 400 milligrams of sulphur dioxide per kilogram, potato doughs a maximum of 100 milligrams.

Most people can tolerate sulphur dioxide and sulphites in food well, as an enzyme produced naturally in the body ensures that the substances are broken down quickly. However, some people show strong intolerance reactions. In asthmatics, added sulphur compounds can cause swelling of the airways and an asthma attack. Sensitive people with existing skin allergies may show a reaction similar to an allergic reaction. People who lack the enzyme to break down the sulphur compounds react with nausea, vomiting, diarrhoea, headache or similar allergic symptoms.

Because of the possible intolerance, sulphur dioxide or sulphites must be labelled in foods from a concentration of 10 milligrams per kilogram or per litre.

Pure sulphur is not toxic for us humans, it passes unchanged through the intestine and is excreted again.

Larger amounts of some sulphur compounds can cause pathological changes in the body. The effect of some enzymes can be inhibited, the effect of carcinogenic substances can be increased. The gases sulphur dioxide and hydrogen sulphide are also toxic in higher doses; an overdose can irritate the respiratory tract and cause coughing, nausea or vomiting. High overdose can lead to respiratory distress or even coma.

The mineral sulphur is found in many foods. In a normal diet, we consume it in sufficient quantities. Sulphur is also found in various preservatives that preserve food and prevent colour, flavour and vitamins from degrading on contact with oxygen. Different foods have different limits for added sulphur dioxide. Most people can tolerate sulphur dioxide and sulphites well, only a few show intolerance reactions. These people particularly benefit from the labelling requirement for sulphur dioxide and sulphites.