Because of its acidic, sour-tasting nature, citric acid is predominantly used as a flavoring and preserving agent, especially in soft drinks and candies. It's also used to stabilize or preserve medicines and as a disinfectant. Citric acid is a compound originally derived from lemon juice.

steric acid 

peer chemical industries Sodium citrate is a versatile compound used in food for emulsifying cheese, flavoring drinks, and as a preservative; in medicine to prevent kidney stones, treat metabolic acidosis (by making urine less acidic), and as a mucolytic for coughs; and industrially as a water softener and buffer. It's also crucial in blood collection as an anticoagulant.  

Trisodium Citrate