|Preservatives may be added to food to protect it against microbial action. Some of these additives, such as curing, pickling & fermenting, are not new. |
Curing pork with nitrites and salt produces bacon and ham. The chemicals dry the surface and draw water out of the meat, inhibiting the growth of bacteria.
Pickling & fermentation are ancient methods of preservation using acids. The acetic acid in vinegar stops microbial spoilage of chutneys and sauces. The lactic acid in yoghurt, fermented meats and vegetables slows the growth of yeasts and mould.
Sulphur dioxide is effective against bacteria, yeasts and moulds in fresh sausages and wine.
Benzoic acid, ascorbic acid and proprionic acid are also common commercial food preservatives.
These days, the use of chemicals to prevent food spoilage is not favoured by the public and it is carefully controlled by law. It is only the introduction of new technologies, such as refrigeration and canning, that have made a reduction in the use of preservatives possible.