Concentration of proteins from single component solution using a semibatch foaming process

A laboratory-scale foam separation system was employed to examine the enrichment and recovery of six proteins: sodium caseinate, β-casein, bovine serum albumin (BSA), β-lactoglobulin, α-lactalbumin, and chymotrypsinogen A. In this report we present experimental data which demonstrate the effectiveness of the separation process in extracting proteins from single component solutions. In particular, we have examined the effects of: 1) the solution pH at a fixed air flow rate and initial protein concentration, 2) superficial air velocity at fixed values of pH and protein concentration, and 3) protein concentration at the optimum pH and at a given superficial air velocity. The maximum enrichment of BSA was obtained at its isoelectric point (pH 4.8), and for other proteins better enrichment was achieved at a pH higher than their isoelectric point. The lower the superficial velocity in the 0.079-0.92 cm/s range the higher the enrichment for all the proteins except for α-lactalbumin and chymotrypsinogen A (for these proteins enrichment was insensitive to the superficial velocity). The higher enrichment was also obtained by foaming at a smaller initial protein concentration (in the 30-120 mg/L range).