Egg white lysozyme purification with a chitin–silica-based affinity chromatographic matrix

Abstract

A composite biosorbent retaining non-covalently chitin in between layers of a silicon oxide matrix was assessed for lysozyme purification from undiluted egg white. The matrix can be shaped with big size and high density, thus allowing its efficient separation from the egg-white after the adsorption step. The lysozyme-depleted egg-white can follow its usual commercialisation route. A surface area of 142 m2/g and a total pore volume of 0.295 cm3/g were calculated from the nitrogen sorption isotherms. Its water content was 78.3 %. The matrix structure is the result of the polysaccharide addition to the polymerisation mixture which is known to influence the condensation process, leading to a material with characteristic properties. A maximum capacity of 117.1 ± 9 mg lysozyme/g and a dissociation constant of 0.73 ± 0.15 mg/ml were calculated from the Langmuir isotherm. A lysozyme purification batch process from undiluted egg white was developed, where 87 % of the lysozyme was removed from the egg white and the matrix was easily recovered by a simple filtration through a strainer. The overall yield of the process was 64 % with a purification factor of 20.