Preservatives

Preservation began with traditional processes, no less chemical in their effects for that: salt, wood smoke, resin in wines.

Many foods go off appallingly quickly without preservatives and wastage of food between the field and the table is still a problem (in Russia, with its huge size and poor infrastructure it is one of the country's main problems). Many of the moulds that grow on decaying food are dangerous: the most notorious case in food history is the fungus ergot which used to grow on rye bread causing mass epidemics hallucinogenic delusions.

Traditional preservatives have been used for centuries to combat the decay of foods. Wood smoke was the first, followed by vinegar, and honey. Traditional preservatives, such as smoking, salt and vinegar are still used and they do not, of course, have E-numbers. Smoking is actually the most dubious of methods because smoke contains a large number of polycyclic hydrocarbons, many of which are known carcinogens.

Preservatives work by killing or stopping the growth of microorganism.

All organisms require a narrow range of conditions in which to live:

too acid or too sweet and nothing, not even bacteria can live (it might seem surprising that sugar is a preservative, but jam, so long as water doesn't settle out is far too sweet for bacteria, plaques of mould on jam occur where water has formed on the surface, significantly diluting the concentration of sugar).

Sulphur dioxide, the most widely used preservative, has actually been in use since the Middle Ages.

The more modern preservatives such as potassium sorbate and sodium benzoate are specific inhibitors of bacteria, in effect they are broad-spectrum antibiotics. Most of the preservatives are simple chemicals, very closely related to natural substances:

• benzoic acid (E210) for example, occurs in several fruits (including the Scandinavian Cloudberry which has 50 times the legal limit of benzoic acid) and it is widely used in fruit preservation.
• Sorbic acid, E200, the most widely used preservative, is an unsaturated acid found in some plants.
• Nisin (E234) which is a natural substance occurring in milk and Cheddar and Cheshire cheeses.
• Propionic acid(E280) is a simple acid closely related to vinegar and it is used in bread manufacture as a more effective preservative than vinegar. Ironically, vinegar as a traditional preservative does not have an E number, propionic acid does: E280. Consumers may feel more comfortable with vinegar than E280 but this is totally irrational.

Preservatives work by preventing the formation of microorganisms, some of which are exceedingly dangerous. Preservatives themselves are generally safe.

There is some concern about the use of sodium nitrite, used in meat preservation. During cooking nitrites produce nitrosamines, which are known carcinogens. It seems likely that the body has ways of neutralizing nitrosamines but processed meats preserved with nitrite now have added vitamins C and E, antioxidants which prevent the formation of nitrosamines, just to be sure. Nitrosamines are also produced in green vegetables.