The ultrafiltration efficiency and mechanism of transglutaminase enzymatic membrane reactor (EMR) for protein recovery from cheese whey

Transglutaminase was immobilised onto a polyethersulfone membrane surface and the resulting enzymatic membrane filtration efficiency and mechanism for the catalysis of protein cross-linking and separation from cheese whey was investigated. Transglutaminase was confirmed to be covalently immobilised onto the polyethersulfone membrane surface by Fourier transform infra-red and X-ray photoelectron spectroscopy. The protein recovery rate reached 85% in the transglutaminase enzymatic membrane reactor (EMR). The observed decrease of the protein recovery rate and relative membrane flux over time were mainly due to the decrease in enzymatic activity on the membrane surface after 1365 min of continuous operation. The total membrane resistance of the EMR was approximately 50% less than that of pure polyethersulfone membrane whey filtration. The main cause of the decreased resistance was that repulsive force energy was observed between cross-linking proteins and enzymatic membrane, which was identified through analysis based on the extended Derjaguine-Landaue-Verweye-Overbeek (XDLVO) theory.