Fractionation and Purification of Bioactive Peptides

Fractionation and purification represent the intermediate steps after the peptide has been released from the parent protein molecule as a result of food protein hydrolysis but prior to mass spectrometry and bioinformatics analysis. This chapter discusses the peptide fractionation based on three major separation techniques: membrane technology, electrophoresis, and chromatography, with different underlying principles. Ultrafiltration is commonly applied after protein hydrolysis to enrich bioactive peptides from a complex mixture of peptide pool containing desirable and undesirable compounds. Electrodialysis coupled with ultrafiltration membrane has come into play. Electrophoresis applies electrical current to induce movement among charged peptide molecules to achieve separation. Two electrophoretic techniques remain popular to date, namely, gel-based electrophoresis and capillary electrophoresis. Ion exchange chromatography was introduced in the late 1940s to separate proteins and was then developed to separate other charged biomolecules, including peptides and nucleic acids, based on the net charge difference among the analyte of interest.