Citric acid has many functions and can be used in place of fresh lemon juice.
Add citric acid to caramel to prevent crystallization, to ice cream as an emulsifying agent to keep fat from separating, or to add a sour flavor to the item you are making.
It is also used in soft drinks.
Citric acid is similar to ascorbic acid and sorbic acid but is considered to be the weakest of the three.
Antioxidant naturally present in citrus fruits.