Using Preservatives
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). |
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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.
Potassium and
sodium nitrate
(E249 and E250)
Sorbic acid and its salts (E200-203)
Sorbic acid (and its salts) are naturally occurring substances and they are among the most important food preservatives for industrialised countries.
Sorbic acid has two main advantages:
- it is effective over a wide range of foods and beverages
- it gives no taste or flavour to products
Sorbic acid is used in beverages, dairy products, fish and seafood, fat-based products, fruit and vegetable products, baked goods and confectionery products.
Benzoic acid and its salts (E210-E213)
A widely used preservative that is important in developing countries.
It is only used in acidic situations which include non-alcoholic beverages, products prone to spoilage by bacteria and fruit-based products.
Sulfur dioxide and sulfites (E220-E228)
This preservative was known to the Romans, Ancient Greeks and Egyptians who used the gas to preserve wine.
These preservatives are multifunctional food ingredients which act as preservatives, antioxidants and colour stabilisers. They have a much more pronounced antibacterial effect than other preservatives and are therefore used when control of bacterial growth is essential.
Sulfur dioxide is used in a wide range of products including packet soup, dried bananas and apricots, tinned crabmeat, sausage meat, beer, wine, quick frozen chips and jams.
Potassium nitrite and sodium nitrite (E249 and E250)
These synthetic additives are capable of performing many functions in food preparation. They act as preservatives, stabilisers and flavours.
There are health concerns about their use. However, without their contribution there would undoubtedly be many more deaths from botulism which is caused by the bacterium clostridium botulinum.
Potassium and sodium nitrite are particularly important in the preservation of cured meat products.
Propionic acid and its salts (E280-E283)
The propionates are other examples of naturally occurring preservatives.
They work better in the more alkaline conditions of bakery products and may be used, for example, to delay the green mould growth on bread.