Recovery of lysozyme from hen egg white by selective magnetic cake filtration

A new concept for the improvement of the downstream processing and purification is the so‐called magnetic separation. By using surface functionalized magnetic substrate particles, which selectively adsorb the target product, it can be directly separated out of a crude bioprocess stream. These methods are already used for analytical purposes, where only small amounts of functionalized particles are necessary. To apply the same concept at a larger scale, effective and economical procedures have to be provided. First, suitable process equipment has to be developed. Second, the magnetic particles have to be manufactured with a stable surface functionalization and long‐term stability for their reuse. Up to now mainly high‐gradient magnetic separation filter devices are applied for selective magnetic separation. They consist of a magnetic matrix in which the magnetic particles are trapped. In this work, a new magnetic filter is introduced that overcomes the capacity limitations of the current high‐gradient magnetic separation technology. The principle is demonstrated by selective recovery of lysozyme from hen egg white. Prior to the separation experiments magnetic beads with a strong acid cation‐exchange surface functionalization are synthesized. The separation procedure is implemented in only one unit operation. With the implementation of the displacement elution sequence lysozyme can be separated out of a hen egg white solution with a purification factor of PF=36 and a purity P=0.83.