Unit operations for extraction and purification of biological products

Abstract

Extraction and purification is a fundamental step in bioprocess engineering. The production of compounds of biological origin with high aggregated value such as proteins, enzymes, vitamins, essential oils, antibiotics, hormones, and several others requires their separation from complex mixtures. It is characterized by its elevated cost, often due to the need to integrate various purification steps required to achieve the desired purity grade. The complexity of the starting material such as fermented medium and the small concentration of the target molecule are key factors that contribute to the increase in the final product cost. The scale up of the separation is another issue that has to be considered. A strategy for the purification of biomolecules should include four steps with various unit operations in each of them: (1) clarification (removal of insoluble compounds), (2) isolation of the product (capture/concentration), (3) intermediate purification, and (4) polishing (finishing). This chapter addresses the unit operations applied in steps (2)(4) by describing their main principles of operation as well as presenting processes where its application takes place. Unit operations such as precipitation, extraction with Aqueous Two-Phase Systems, chromatography, crystallization, lyophilization, and spray drying will be considered.