Citric acid is a weak organic acid. It is a natural preservative and is also used to add an acidic, or sour, taste to foods and soft drinks. It also serves as an environmentally benign cleaning agent and acts as an antioxidant.
Citric acid exists in a variety of fruits and vegetables, most notably citrus fruits. Lemons, limes and chokeberries have particularly high concentrations of the acid; it can comprise as much as 8% of the dry weight of these fruits.
As a food additive, citric acid is used as a flavouring and preservative in food and beverages, especially soft drinks. It is denoted by E number E330.
Use in baking
Crushed vitamin C tablets can be used as a substitute for ascorbic acid in wholegrain bread recipes, where it helps sustain the leavening of bread loaves during baking. It also helps produce the acidic atmosphere in which yeast grows best.