Because food is so important to survival, food preservation is one of the oldest technologies. Different ways and means have been found and improved for the purpose, including the traditional methods of boiling, freezing, refrigeration, pasteurising, dehydrating and pickling.

Chemical preservatives have been used for many years. Preservatives are ingredients that either retard the growth of microorganisms or kill them. The three main groups of food spoilage microorganisms are bacteria, yeasts and moulds.

The four main preservatives we usually encounter in the food industry are;

Sorbic acid and potassium sorbate (potassium salt of sorbic acid)
Sodium benzoate (sodium salt of benzoic acid)
Sodium lactate
Sodium metabisulphide (the most commonly used form of sulphur dioxide)

The functional part of these ingredients is usually found in the acid form. However, propionic acid, sorbic acid and benzoic acid are all relatively insoluble in water. While the salts are more soluble, all dissociate into their active form at various pH's and may not be active under certain conditions.

HWA offers the following preservatives:

Sorbic acid and potassium sorbate are effective against yeast and mould, but with little activity against bacteria. Sorbic acid has low solubility in water, which increases with increasing temperature, while potassium sorbate is readily soluble in water.

Potassium sorbate has the best activity (greater dissociation into sorbic acid) up to pH 5.5, but will usually have some effect up to pH 6.5. Potassium sorbate is widely used in cheese, fruit products and chemically leavened baked goods.

Sodium benzoate is effective against yeast and has some effect against bacteria and mould. The most effective pH range for sodium benzoate is pH 2.5 to 4.0, although it can sometimes be used up to pH 4.5. It is commonly used in fruit products and carbonated beverages.

Disclaimer
The maximum dose rates of all products are prescribed by law, and you must check these out:

Food Standards Australia New Zealand (FSANZ)

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