Citric acid is a weak organic acid with the formula C6H8O7. It is a natural preservative/conservative which occurs naturally in citrus fruits and is also used to add an acidic or sour taste to foods and drinks.
Citric acid was originally extracted from lemons and limes but it is now produced commercially by a fermentation process. The mould Aspergillus niger is used to ferment a carbohydrate source such as molasses.
Citric acid is a commodity chemical, and more than a million tonnes are produced every year by fermentation. It is used mainly as an acidifier, as a flavoring, and as a chelating agent.
Citric acid is widely used in the food industry to:
- provide sharp taste in soft drinks and sweets
- generate the optimum conditions for the formation of gels in jams, jellies, confectionary and desserts
- help give the conditions for the stabilisation of emulsions (e.g. processed cheese and dairy products)
- prevent the browning of salads
- enhance the action of antioxidants and prevent deterioration in frozen food
- act as an antioxidant in fats and oils
- preserve meat products and help modify their texture during their processing
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