Preservatives are often present in nature but they are in such small quantities that it makes them difficult to obtain. To obtain commercially-useful amounts of the preservative, they are produced as synthetic copies of the natural products. Other preservatives are made in the food factory using a series of chemical reactions.
Typically, preservatives attack the enzymes inside the microbes and this stops their cell reactions. Some can disrupt the microbe's cell wall so that substances cannot enter or leave the cell. These two processes kill or seriously slow the growth the food-spoiling microbes.
Probably the most important use of preservatives from the food safety point of view is in processed meats such as ham, bacon, salami and sausages. Bacteria like clostridium botulinum can produce deadly poisons and the use of preservatives in such products is absolutely essential. For example, most cured and cooked meats contain the preservative potassium nitrate (Saltpetre).
The Range of Preservatives
There are over 80 substances which have permitted use as preservatives. The list below shows some important preservatives, click on the names to get more information.