Preservatives

Preservatives (synonym: preservatives) serve as antimicrobial biocides (substances or preparations which, according to their intended use, have the property of killing living organisms or at least restricting their vital function) to eliminate microorganisms. They are intended to prevent the spoilage of food by bacteria, yeasts and molds and thus the occurrence of dangerous diseases such as botulism, listeriosis and salmonella infection. In addition, the use of preservatives allows for longer transportation distances and storage times. Preservatives are used when physical processes such as heating (pasteurization, sterilization), dehydration, air sealing and freezing are no longer sufficient. They must be declared on the food with name, generic name and the corresponding E-number (preservatives: E 200 – E 290). Preservatives are used in the following foods: Bread and baked goods, canned fruits and vegetables, salads and salad dressings, acidified vegetables, dried fruits, dried potato products, sausages, fish products, fruit yogurt, cheese, margarine, snack foods, sodas, fruit juices and wine, as well as on the surfaces of citrus fruits. Preservatives are also used in pharmaceuticals and cosmetics. There are approximately 40 approved preservatives. Among the most commonly used are:

• Benzoic acid (E 210) – in fish products, acidified vegetables, olives, sauces, sugar-reduced jams, jams, jellies, non-alcoholic draft beer and spirits.
• Sulfur dioxide (E 220) – in dried potato products, canned fruit, wine, dried fruit and snacks.
• Sodium nitrite (E 250) – for preserving meat and sausage products.
• Potassium nitrate (E 252), sodium nitrate (E 251) – for preserving meat and sausage products, for hard and semi-hard cheeses.
• Natamycin (E 235) – for the surface treatment of sausage and cheese.

In the following, the preservation by means of common salt (sodium chloride) and nitrates and nitrites are discussed in more detail.

Common salt (sodium chloride)

The preservative property of salt has been known to mankind for a long time. Traditionally, table salt is used to preserve meat, fish and vegetables.Table salt is not one of the additives and is therefore listed as a separate ingredient. Table salt, which is industrially manufactured and refined salt and thus represents pure sodium chloride, is added to food in high concentrations. This, together with potassium and calcium, keeps the fluid balance in our body in equilibrium. High amounts of salt are found in convenience foods, smoked meats and fish, cheese, salty snacks such as nuts and chips, as well as canned vegetables, soups and sauces, and many other industrially manufactured products. In these foods, however, you can’t taste the high salt content because added sugar masks the salty taste. For this reason, many people season their food with additional salt. Thus, the food contains considerably more sodium chloride than is actually needed – namely only 200 to 300 mg per day. The kidneys are overloaded because they can filter out only 5 to 7 grams of sodium chloride per day, but 15 to 20 grams are ingested at peak times. The result is excess sodium in the body and increasing calcium and magnesium losses through the urine. As a result, the balance between sodium, potassium and calcium can no longer be maintained. For example, a canned tomato soup has over 1,200 mg of sodium and only 400 mg of potassium. Natural and fresh food, on the other hand, contains less than 10% salt and shows a balanced ratio of sodium to potassium. Thus, industrially produced foods, which today’s people give priority to over natural, healthy foods, contain only small amounts of the minerals potassium and calcium compared to their high sodium content. Due to the excess of sodium chloride, the fluid balance in our body is disturbed by increasing the fluid outside the cells, which can cause further health problems. In some people, over time, this excess salt can lead to edema (fluid buildup in tissues), hypertension (high blood pressure) – and subsequently heart and kidney disease and apoplexy (stroke). The relationship between salt consumption and the level of blood pressure can be considered established.The role of common salt in the development of arterial hypertension (high blood pressure) is not yet clearly understood. A probably genetically determined salt sensitivity (synonyms: salt sensitivity; saltsensitivity; saltsensitivity) affects only a part of the hypertensive patients, however, there are currently no practicable tests with which salt-sensitive can be found. Reducing salt consumption to approximately 4-6 g/d results in a clinically relevant reduction in blood pressure, independent of existing drug therapy, which means that an additional reduction in blood pressure can be achieved in most cases (see “Saline/Salt Sensitivity” below).

Nitrates and Nitrites

Nitrates are used in food production as preservatives and to improve color and flavor for cured meat products and fish. Na-nitrate (E 251) and Ka-nitrate (E 252) are permitted as a component of curing salt in combination with NaCl. However, the intake of nitrates occurs only to a small extent via the additives E 251 and E 252.The daily intake of nitrate occurs:

• To about 70% through the consumption of vegetables – nitrate as the most important plant nutrient has damaging effects on the soil and plant growth if the intake is excessive. Some vegetables can store high amounts of nitrate from the soil.
• To about 20% from drinking water – nitrate enters the groundwater as a component of nitrogen fertilizer. Information about the nitrate content of drinking water provides the local waterworks.
• To about 10% from meat and meat products and fish.

Nitrates in themselves are not toxic and harmless. Health risks arise from nitrites and nitrosamines, which are formed from nitrates in the food itself and in the human organism. However, it should be mentioned that nitrates inhibit the formation of vitamin A and are thus responsible for its deficiency, among other things.nitrate is reduced to nitrite in our body by bacteria already in the oral cavity, but also in the gastrointestinal tract. The effectiveness of nitrates as a preservative against bacteria is not mediated by nitrate itself, but by the nitrite that results from the microbial conversion of nitrate. However, since this microbial conversion process cannot be controlled, nitrites are also used directly. Permitted preservatives are Na-nitrite (E 250) and Ka-nitrite (E 249) as a component of pickling salt in combination with NaCl. Nitrite then causes the desired reddening of the meat – myoglobin becomes the red nitrosomyoglobin -, contributes to the formation of the curing aroma, has an antioxidant effect and, in combination with NaCl, protects against “sausage poisoning” by preventing the germination of the heat-stable Clostridium botulinum spores. Clostridium botulinum is a bacterial species that produces the most potent of all bacterial toxins known to date, botulinum toxin, which acts on the nervous system.In addition to the positive effects of nitrites on meat quality, the effects of concern for the human organism are methemoglobin formation (secondary effect) and the formation of carcinogenic nitrosamines (tertiary effect):

Methemoglobin formation: Nitrite is a reactive oxidant that reacts preferentially with the blood pigment hemoglobin, converting it to methemoglobin (the divalent iron of hemoglobin is oxidized to trivalent iron). The formed methemoglobin is unable to reversibly bind molecular oxygen and is thus no longer available for oxygen transport. Even without nitrite, methemoglobin formation occurs, but to a much lesser extent. In adults, the amount of methemoglobin in the blood is regulated by NADPH in the enzyme methemoglobin reductase to a level < 2% and no health problems occur. Infants are particularly at risk until about six months of age, since in them the protective system that can convert methemoglobin back into the oxygen-transporting form is not yet fully developed.Nitrosamine synthesis (nitrosation): nitrite can react with other endogenous substances, such as secondary amines, and form so-called nitrosamines in the acidic environment present in the stomach. These are considered to be highly carcinogenic. Higher amounts of secondary amines are contained in meat and sausage products and very high amounts in cheese and fish. In addition, secondary amines can be formed during the breakdown of proteins.nitrosamines can also be formed exogenously.Heating cured sausage and cheese together is particularly dangerous. A good example of this is “Toast Hawaii”.The nitrite from the meat and the amines from the cheese react particularly well to form nitrosamines.Vitamin C inhibits the synthesis of nitrosamines by reducing nitrite very quickly, thus removing it from nitrosamine synthesis. Vitamin E also acts as a nitrosation inhibitor.Some foods already contain nitrosamines. Beer in particular is rich in them. Cured meats also contain small amounts of nitrosamines. A potentiation of this content is achieved by heating cured goods. For example, when cured meat is grilled, nitrosamines can be formed from protein compounds and nitrites under high heat.The current limit for nitrate in drinking water is 50 mg/l and for nitrite 0.1 mg/l, according to the German Drinking Water Ordinance. If the label states “Suitable for the preparation of baby food”, the nitrate content may be a maximum of 10 mg/l and the nitrite content 0.02 mg/l.The DGE (German Nutrition Society) and the WHO (World Health Organization) assume an acceptable amount of nitrate of 220 mg/day. Preservatives can trigger allergies or allergy-like symptoms (pseudoallergies) in sensitive individuals or in individuals suffering from bronchial asthma or who are already allergic to salicylic acid (contained in acetylsalicylic acid/ASS) and its derivatives. In this context, particular mention should be made of the preservatives benzoic acid and its derivatives and sulfur dioxide, which can cause diarrhea, headaches, and allergies in children.The following is a tabular overview of the preservatives that can trigger allergic (A) and/or pseudoallergic reactions (P).

Harmless preservatives include formic acid (E 236) – in fish products, fruit and vegetable products – and natamycin (E 235).