Multi-Component Fractionation in SMB Chromatography for the Purification of Active Fractions from Protein Hydrolysates

Abstract

Some separations in food and biotechnology concern enrichment of a (multi-component) product in a particular functionality, for instance from a health or nutritional point of view. For instance, when using chromatography, the functionality can be associated to a particular multi-component fraction of an—also—multi-component feedstock. Developing and optimizing an efficient separation has to deal with the inherent multi-component nature of the feedstock and product(s). Simulated moving bed (SMB) chromatographic separations are known for the efficient separation of well-defined bulk chemicals streams such as binary sugar mixtures or xylene isomers. Therefore, this work is focusing on the feasibility of SMB technology for the group of industrially relevant multi-component separation problems. As a typical example, the feasibility of SMB size exclusion chromatography for the isolation of bioactive components, peptides, capable to inhibit the ‘angiotensin-converting enzyme’ (ACE) from a casein hydrolysate for use in functional foods is investigated. Fixed bed (FB) experiments were used to select a proper stationary phase (Toyopearls HW40 C), and buffer, and to determine the partitioning coefficients of the key components. Components with a large volumetric partitioning coefficients (K > 0.75) and a low molecular weight proved to have the highest specific bioactivity. SMB experiments were designed on the basis of measured partitioning coefficients. Three experimental strategies were used to determine the effect of changing ratio of liquid and simulated solid flow rates at constant throughput, a variable throughput and a variable feed concentration, respectively, on the composition, purity and biological activity of the produced fractions, as well as the recovery of the components. High product purities containing the active fraction (> 98%) could be achieved using SMB. Increasing the liquid flow rate at constant simulated resin flow rate (i.e., constant switch time) and throughput yielded an increase in bioactive product purity at the expense of the product recovery. By increasing the throughput, both the purity and recovery of both products were decreased, due to the inevitable presence of ‘intermediate components’. A 10-fold decrease in feed concentration had no clear effect on the separation.