The process of separating and purifying expressed proteins or products before marketing is known as Downstream Processing.

Downstream processing involves a series of steps that occur after the production of a desired product (such as recombinant proteins, enzymes, or pharmaceuticals) using biotechnological methods. This phase involves purification, separation, and refinement techniques to isolate and purify the target product from the biological source. These methods include various purification techniques such as chromatography, filtration, centrifugation, and other specialized processes aimed at obtaining the final product in a highly purified and concentrated form suitable for medical or commercial use.

Therefore, the correct term for the process of separating and purifying expressed proteins or products before marketing is Downstream Processing.