Purification of Product - The final step in the recovery of a product is purification, which aims at obtaining the product in highly purified state. Purification is achieved by

(i) crystallization and
(ii) chromatographic procedures.

Crystallization
It is mainly used for purification of low molecular weight compounds like antibiotics, e.g., penicillin G is usually extracted from fermentation broth in butyl acetate and crystallized by the addition of potassium acetate in ethanol solution. Crystallization is the final stage in purification of products like citric acid, sodium glutamate, etc.